Friday, February 28, 2014

Compost with a Capital 'P'

A last spring, we wrote about a few ways we reduce the water used by our toilet.  Unfortunately, most of those methods still result in the loss of the valuable nutrients in our urine.  We've read a lot of anecdotes about using urine in a compost pile and how great it is for 'activating' the pile (e.g., page 149 of the Rodale Book of Composting).  But the assumption always seems to be that there is already a 'pile' to which the urine can be added.  What about all those budding homesteaders who might want to recover these nutrients, but don't have a place for a compost pile?  What about all those skinflints like us, who want to make use of all of the urine, not just enough to 'activate' a compost pile?  What about especially territorial people with a compulsion to deter would-be compost thieves by marking their compost as theirs alone?

It's possible to dilute the urine and use it to water plants, but because of urine's high nitrogen and salt content, we've got to be careful about using it that way too frequently, especially on potted plants.  (Although there is an interesting story about a sort of in situ urine composting experiment in Mexico City.) Similarly, if we had a fishless aquaponics setup, we could convert it to be pee-powered, but that would also be maxed out before long.  It's obviously possible to distribute it around the yard and count on rain to dilute it before we have to pee in the same place twice, but again, what about those poor blokes with an apartment and no yard?  (Don't apply the 'distribution' principle to the back deck--your downstairs neighbors will not forgive you no matter how many plates of cookies you bring them.)

In the interest of full disclosure, we confess that we now have enough space for full-size compost bins.  Can you guess which side has some of the chicken leftovers in it?

That got us wondering what would be the minimum-size compost pile that is able to absorb 100% of our pee, or, alternatively, how frequently would we have to make a new pile for a given pile size (e.g., a five-gallon bucket).  And now that we've spent way too much time playing with engineering calculations (this post was originally going to come out on Sunday, but we got lost somewhere in Nerdland...), we figured it was time to wrap up our theoretical composting, summarize the results here, and start practicing.

It turns out that a human produces (normally) 0.8 - 2 liters per day, of which around 95% is water, and the other 5% is made up of nitrogenous waste products like urea and creatine, and some inorganic substances like potassium and phosphorus.  The C/N ratio is on the order of 0.8:1.  The very high moisture content and very low C/N ratio make it difficult to balance a compost pile with a high fraction of urine.

A proper compost pile will have a moisture level of 50-60% and a C/N ratio of around 30:1.  Higher moisture contents limit the access of air to the pile and can cause anaerobic conditions, which lead to stinkiness.  The organisms that turn the raw materials into finished compost need a C/N ratio of about 25:1--too much higher and the pile takes forever to break down (and doesn't get hot enough to kill weed seeds or plant pathogens), too much lower and the excess N lets the bacteria make the pile too hot and they die, which in turn also leads to anaerobic conditions and stinkiness.  It's worth noting that C/N ratios closer to 35:1 will preserve more of the N in the finished product.

So, the golden question remains: how much urine can I add to various materials to make an optimal compost pile?  The calculations we need to do can be found here, but we wanted to (potentially) check out a lot of different combinations and have the ratios automatically calculated. We needed a spreadsheet.

We took the most recent version of Cornell University's compost spreadsheet and tricked it out a little to make it more user friendly (in our minds, anyway).  We imported a table of different materials one might want to compost (also from Cornell), and filled in some of the missing data with other info from the Internets. (Urine wasn't in the table? Seriously?)  We also automated the section on the first sheet to select materials from a dropdown list based on the table we imported (except for a few odd materials like pharmaceutical waste--for those you're on your own), and the moisture, carbon, and nitrogen contents are automatically populated.

We also added a feature to specify the volume of the pile desired, and added an 'error' box to let Excel numerically solve for the most optimal mixture of the ingredients selected.  So, even if it's not possible to get exactly the target moisture content and C/N ratio with the ingredients selected, you can use Excel's 'Solver' function to see how close you can get. (One caveat is that you might have to try multiple starting points when optimizing because numerical solvers can get stuck at local minima--i.e., there can be more than one composition that 'minimizes' the error.)  The spreadsheet can be downloaded here.

Ok, then.  What did we find?  Well, as we hinted above, we found that it's very difficult to balance a compost pile with a high urine content because of its high moisture content and low C/N ratio.  We were most interested in balancing it with just dry leaves or just wood shavings, since those are the ingredients of which we currently have an abundance.  But, if we balance the C/N ratio, the moisture content is too high.  And if we balance the moisture content, the C/N ratio is too high.

The first look--attempting to balance compost ratios with just urine and a high-carbon ingredient.  The 'Actual' moisture content and C/N ratios are the optimized compositions based on error minimization from Excel's Solver function. Note that oat straw gets the closest of the high-carbon materials.  So to those folks advocating straw bale urinals (and here), we say, 'touché!'  (Also, in hindsight, maybe labeling the second ingredient '#2' wasn't such a good idea for this post...)

However, if we add urine, a high-carbon material, and some food scraps, like would normally be found in a standard backyard compost pile, we can get a pretty good balance.  With the two main high-carbon resources on our homestead, we can mix up a five-gallon bucket with about a half-gallon of urine.  If we had oat straw, we could get up to 0.66 gallons of urine per bucket.

Second attempt, with the third ingredient being food scraps.  All of the high-carbon materials will work for some combination.  (Fresh) grass clippings still don't work because they're on the same side of the target C:N ratio as the urine and the food scraps. 
The upshot is that, if we wanted to keep a five-gallon bucket in the garage and do all our peeing there, we'd need a fresh five-gallon bucket every 1-2 days.  If we do half our peeing away from the home (e.g., at work, on the neighbor's bushes, etc.), we could extend that to 2-4 days, or about two buckets per week.  That would still add up quickly.  The other problem is that the compost won't get very hot (unless we insulate it really well) because a five-gallon bucket is too small.  That in turn means that the materials will take longer to break down, and we would rapidly amass a small army of five-gallon buckets full of ingredients about which our neighbors and guests probably wouldn't want to know, but would probably ask.  (Sorry for the bad news, apartment dwellers.)

On the other hand, if we had a compost bin at the recommended standard size of one cubic yard (202 gallons), we could handle 20 gallons of urine in the pile, which would keep us covered for 6-12 weeks. That's the same time frame as experienced compost chefs say will be required for finished compost with biweekly instead of bi-daily turning of the pile.  Thus, in theory anyway, a regular-sized compost bin should be able to supply one person with all the pee absorption they need.

In reality, that size pile can probably do more than that for a couple reasons.  First, we're adding the ingredients gradually over time, meaning that the early additions start breaking down and losing volume before the last batch is even a twinkle in our water bottle's eye.

Second, we haven't accounted for evaporation of water or nitrogen (as ammonia, NH3), which can be significant.  The evaporation rate depends on a lot of things, including temperature, atmospheric pressure (to a small extent), relative humidity, wind speed, and surface area.  There are a number of models one can use to predict the evaporation rate for a given set of environmental conditions, but just for fun (nerd fun, anyway), we calculated the evaporation rate we'd expect just by diffusion (based on Example 1.2-2 here), the simplified model developed by Irving Langmuir for a different purpose, and the model NOAA uses to estimate evaporation rates of chemical spills.

Of the three, the diffusion model goes too slow, the Irving model seems way too fast, and the NOAA model seems about right, based on our intuition and love for the baby bear in everything.  (The calculations are also included in the spreadsheet if you are interested in channeling your inner nerd and/or checking our work.)  From the NOAA model, we would expect to lose about 0.5 pounds of water every 10 days from a five-gallon bucket (at a temperature of 68 °F and 45% relative humidity).  By contrast, these same conditions would lose upwards of four pounds of water per day from a 3' x 3' x 3' cubic pile, if the five sides not facing the ground are all included.  That assumes a very modest wind speed of 0.7 m/s, which is in the range that one sees inside a house just from natural convection (e.g. near a cold window or warm radiator).  Also, 68 °F is a pretty modest temperature for a compost pile, so the actual water loss rate is probably even higher.  (Heavy evaporative losses are also common in industrial compost setups.)  Rain on the compost pile washes some of the urine away into the surrounding area, which spreads out the urine burden even more.

Bottom line is, a standard 3' x 3' x 3' compost pile is conservatively about the right size to handle all the urine from one person.  If you want to calculate for your own needs, scale from there according to volume, number of people, and personal risk tolerance.

Do you compost your own pee?  How big a compost pile do you use?  What's your setup?  Let us know in the comments section below!

Thursday, February 20, 2014

Updating the Intergral Urban House: Chapter 2

Back in November, we started working our way through The Integral Urban House, a seminal book on urban homesteading, with the objective of updating the book's excellent but 35-year-old data.  We took a few month-break but we're back and ready for some Chapter 2 action.

Chapter 2 is an introduction to the material and energy balances of the IUH, and also the trippy graphics that characterize the book.  The authors give a high-level overview of the energy flow through their homestead in terms of btu/week, the IUH's nitrogen cycle in terms of lb/week, and a number of other nutrients.   

On their 0.2-acre lot (in Berkeley, CA), the Integral Urban House was able to produce 43% of their food and 44% of their energy needs (for five adult humans) while drastically reducing their outputs to the sewer and landfill. 1Wikipedia, 2EPA

These graphics are remarkable for two main reasons--the visualization of energy and nutrients as resources to be recycled (and ways to recycle them) instead of inputs and outputs that flow linearly through the homestead system, and the degree of quantification achieved by the authors (thorough even by today's standards!).  Along with cyclically-flowing resources, the authors also discuss the benefits of a certain degree of redundancy for generating these resources and capitalizing on the byproducts of their use.  For example, heating by passive solar energy when it's sunny, but having a wood stove for cloudy days, and having the option to send organic wastes to worms, chickens, or compost (if both the worms and chickens are full).  The same concepts were being simultaneously pioneered by Bill Mollison, David Holmgren, and Sepp Holzer, and introduced decades earlier by Joseph Russell Smith (Tree Crops book linked here), Toyohiko Kagawa, and Masanobu Fukuoka (among others).

Perhaps an update to this chapter would be a carbon balance and cycle.  Not just in terms of CO2 consumption and emission, but soil and plant carbon balances.  Many homesteaders, both urban and rural, are continually on the search for high-carbon substances for balancing compost composition, increasing soil organic matter, firewood, building materials, etc.

It seems that a significant fraction of 'sustainable living' can be attributed to high-fertility soil, which can often be attributed to organic matter imports from outside the homestead property.  These materials are wonderful amenities now because they are readily available, cheap (or free), and often considered waste by non-homesteading-minded folks.  But for true sustainability, shouldn't the organic materials come from the homestead property itself?  Surely if everyone tried to 'live sustainably,' the hundreds of pounds of free horse manure and old cedar fence panels from Craigslist (way more exciting than it sounds) would quickly vanish, accompanied by an eventual decrease in the soil fertility/sustainability of a given homestead.

The natural follow-up question is, what is the minimum acreage required to make a 'carbon-neutral' homestead possible? The answer to that question will obviously vary widely by region--five acres in northern Georgia will produce way more carbon than five acres in the Nevada desert.  But if, like in the Integral Urban House, we convert everything to units of energy and compare with other studies, we can come to a ballpark (or at least average) number.

Figure 2-4 of the IUH says they import 150 thousand british thermal units (kbtu) as non-vegetable food, 1,250 kbtu as fuel (petroleum, natural gas, electricity, and wood), and use about 5,000 kbtu as solar energy to grow plants.  Then they import another 196 kbtu as vegetable-type groceries, 120 kbtu as animal feed, and 19 kbtu as meat groceries, bringing the grand total to 6,615 kbtu per week, or 343,980 kbtu per year.

The famous Billion-Ton Study, published by the US Department of Energy in 2005, said that of the 2.263 billion acres encompassed by the US, around 50%, or 1.132 billion acres, is suitable for biomass production (pg. 20).  This amount of land could produce 1.366 billion tons (3005.2 billion pounds) of biomass (feedstock for fuel for them, but approximating food, fuel, etc. for us) per year (pg. 17), with some modest assumptions about yields and recovery costs.  Since the combustion energy of biomass is conservatively around 6.45 kbtu/lb, that means that it should be possible to produce 8,565.4 kbtu per acre per year.  Dividing the number for the IUH by the number from the DOE gives 40.2 acres for the IUH to be perfectly balanced.  There were five people living there, so that works out to about 8 acres per person. (Using the upper range of 8.20 kbtu/lb for biomass combustion drops that number to about 6.3 acres per person).

Crude calculation for minimum number of acres required per person for homestead carbon neutrality, based on an IUH-level lifestyle and diet.

That number represents an average across the US and is a little higher than the number derived by a Swedish university organic farm last spring of a little over one acre per person.  However, the Swedish study used a base case of 80 acres, which isn't infinitely down-scalable: it wouldn't work to grow 1/6 of a cow on 1 acre, for example.  The Swedish study also put a high emphasis on food calories regardless of source, which strongly emphasized dairy and de-emphasized vegetables and meat.  Therefore, although our calculation here is a little more crude, 8 acres per person is probably more realistic, and maybe even a little low if one wants to produce his own grains, dairy, and building materials self-sufficiently.  Also, don't forget to take advantage of direct solar and wind energy, which have efficiency ceilings considerably higher than photosynthesis (which produces biomass).

Chapter 2 of the Integral Urban House ends with a hopeful wish that, much like hot rodders in the 1970s or silly television in the 2010s features folks competing to have the most aristocratic vehicles and houses (or rides and cribs, if you prefer...but tyrannosaurus rex eggs?), future mainstream endeavors will feature a sort of contest to see which crib can be most integrated and sustainable.  The authors might be disappointed with how far the mainstream has come in the last 35 years, but maybe there's a glimmer of hope?

Plus, there's always the internet, with it's endless fountains of sustainability inspiration!

Have you measured the balance of energy and resources on your homestead?  How sustainable did you come out?  What's the size of your homestead and how much organic matter do you import?  Let us know in the comments section below!

Sunday, February 16, 2014

Book Review: Naturally Bug Free by Anna Hess

Anna Hess' new ebook, Naturally Bug Free, is an excellent resource for gardeners who want to combat garden pests, but not with man-made chemicals.  It has a lot of the same advice as other books like Good Bug Bad Bug, and Organic Gardener's Handbook of Natural Pest and Disease Control, but at a fraction of the price.  The main difference is that Naturally Bug Free covers only the most common garden insects in detail (and not bacterial, viral, or fungal diseases at all) , but gives a systematic approach that can be used for the rest. Also, Hess' photography is much better. 

The cover, featuring (clockwise from upper left) a tomato hornworm parasitized by a good wasp, a movie-star praying mantis, an industrious honey bee, and an aphid farm managed by ants (which sometimes make poor life choices).

Hess lays out a number of steps gardeners can take to develop a well-functioning garden ecosystem, starting with an exhortation to 'know thy bugs.'  If an unknown bug arrives in your garden, you must find out it's function.  Is it a pest?  Is it benign?  Is it a beneficial insect that moved in to feast on a pest? What and where is the pest it's hunting?  Hess gives a number of resources she uses to identify new bugs in her garden.

After covering a number of garden pests common almost everywhere (based mainly on a Mother Earth News survey), Hess moves on to methods for encouraging friendlies in the garden, from good insects and worms, to birds, amphibians and mammals.  (Spoiler alert not needed by permaculture enthusiasts: maximize landscape diversity and provide habitat for the good guys.)  Some of the beneficials Hess sees in her garden are more prominent in her local environment--with nearby wetlands and high groundwater--than many readers will find in theirs (such as turtles and underground crayfish), but she gives a few pointers that readers anywhere can try.  Hess also points out that a lot of the beneficials have some annoying quirks, such as box turtles that eat tomatoes or birds that take one bite of a strawberry, but notes that their presence is net positive after considering the number of slugs they'll eat.  Even deer, which are definitely net-negative for a garden, can be a valuable source of meat for the gardener.

Hess also gives advice for the time period between establishing a garden and having a balanced ecosystem to keep pests in check.  In this regard, judicious timing of plantings and planting trap crops can be helpful.  Other helpful approaches can be choosing bug-resistant varieties from the get-go (the same approach is  helpful for non-bug pests, too, such as fungi and bacteria) and employing more labor-intensive direct methods of pest control like row covers and hand-picking.

A couple examples of strategic succession planting that Hess uses to time harvests away from peak periods of pests such as squash vine borers and cabbage moths.

The book wraps up by pointing out that even fruits and veggies that aren't grocery store-quality (i.e., that have some cosmetic damage), can still be delicious and nutritious with a little extra trimming.  We whole-heartedly agree, and we wish more authors would tout such an approach.

An excellent epilogue is an excerpt from another of Hess' books, Homegrown Humus, which is especially appropriate given the key role soil health plays in plant health, and consequently plants' ability to fend off pests.

Our only criticism is that, because Hess advocates ecosystem-level management of garden pests by encouraging beneficial predators that depend on a certain minimum population of pests to eat (i.e., a biological equilibrium), the book would more appropriately be titled 'Naturally Bug-Optimal.'  But 'bug-free' definitely rolls off the tongue better.

Have you read Naturally Bug Free?  What did you think?  What methods do you use to naturally control pests in your garden?  Let us know in the comments section below!

Thursday, February 13, 2014


Hey! This is our 100th post!  Hard to believe it's been a year already!

Back in January, we wrapped up our twelfth month of eggnog (but don't be surprised if a few new recipes pop up here and there), and we thought it would be fun to embark on a new egg-related journey.  We've been experimenting on and off for a while, and we decided that strata is a much more versatile dish than it usually gets credit for.  There's the standard ham strata that we grew up on, Reuben strata that we wrote about last March, and a butternut squash strata that we made in the fall but never blogged about.

But really, there's no limit to what can go into a strata, provided we restrict the discussion to edible things food items. (Any Get Fuzzy fans out there?)  Other than bread, cheese, and a sort of eggnog-type liquid, one can really let their culinary creativity loose on a strata.  (Get 'em, boys!)

So we thought we'd start our second hundred posts with a new theme for using up even more excess eggs from the backyard flock.  (Since we know that no one is tired of eggnog or freaked out about drinking it year-round.)

If you noticed the title, you may be wondering at this point, 'what does all this have to do with Vacation Bible School?'  The answer, of course, is that VBS can also stand for 'Venison Broccoli Strata.'  Let's see how Katie did it!

She started with a bunch of bread slices.  Strata is also a good way to use up bread experiments that didn't quite work out, like if it's too crumbly or didn't rise enough.  Save the crumbs!  They'll come in handy later.

These are the rest of the solid ingredients.  Clockwise from upper left: 0.75 lb browned ground venison, 3-4 cups cooked broccoli, 3 cups shredded cheese (or so), and 1 cup sautéed onions.

Grease a 9" x 13" pan, then stratify them like so--bread, meat, vegetables, cheese, then repeat for the second story.  It's generally recommended to use a thicker layer of cheese than what's shown in the picture.  We can usually get two layers of everything, but we slice our bread pretty thick.  If you're lucky, you might be able to get three layers.

Then beat together 2.5 cups milk and 4 eggs.  (Or 3 cups milk and 6 eggs if you got 'em.)  It's kind of like eggnog!  Add pepper, salt, garlic powder, dry mustard powder and sage to taste.  It's no longer like eggnog.  Pour it as evenly as possible over the layered stuff in the pan.

Aha!  This is where the bread crumbs come in handy!  Mix about a cup of them with 0.25 cups (half a stick) of melted butter, and spread them on the top.

Lookin' good!  We usually let it soak in the fridge for a few hours or overnight.

Then bake it at 350 °F for 50-60 min, until nice and toasty on top.  Mmmmm.

The nice thing about it is, strata is a complete meal!  All the food groups are covered (except dessert).  We cut our pan into eight pieces, and one piece is definitely enough for our supper.

The recipe:
Enough bread for 2-3 layers in a 9" x 13" pan (for us, 12-14 slices of collapsed bread)
0.75 lb ground venison, browned
3-4 cups cooked broccoli
3-4 cups shredded cheese (cheddar or other flavorful flavor)
1 cup chopped sautéed onions
2.5-3 cups milk
4-6 eggs
salt, pepper, garlic powder, mustard powder, and sage to taste (for us, 0.5 teaspoon salt, 1 teaspoon each of the rest)
1 cup bread crumbs
0.25 cup melted butter

Layer bread, venison, broccoli, onions, and cheese in a greased 9" x 13" pan until pan is full.  Beat together milk, eggs, and spices, pour over the layers (in the pan, not your chickens).  Coat bread crumbs in melted butter, add to pan.  Bake at 350 °F for 50-60 min, until cooked through and toasty brown on top.

Have you made strata before?  What kind did you make?  Do you prefer strata or eggnog?  Let us know in the comments section below!

Sunday, February 9, 2014

Historical Lye Making, Part 2

On Thursday, we posted about historical methods to drip lye and some of the chemistry associated with it.  Today, we wanted to talk about measuring the strength of the lye to check if it's concentrated enough for making soap.  In the olden days, that was often done with some sort of density test, either by floating an egg or potato, or matching the density of the lye solution with a saturated table salt solution (sodium chloride, NaCl).  An egg has a density of 1.03-1.1 g/mL, and a saturated NaCl solution is a little more precise at right around 1.2 g/mL, but in our soap calculations, we normally use a solution that is 1.3 g/mL, according to density-sodium hydroxide concentration correlations.  One initial conclusion from that is that old-time soap makers probably used less concentrated lye solutions.  Similarly, older soap recipes often call for cooking the lye water and fat together (i.e., hot process soaps), which probably boils off a lot of the extra water.

For modern homesteaders, who might have a scale and measuring cup handy, it would be much more precise just to measure the density of the lye solution directly.  (A graduated cylinder would make this calculation--and other density calculations you might want to do--more precise, but a measuring cup, used judiciously, should be good enough.

Another technique is to use a pH indicator and either dilute a small (representative) portion of the lye water or titrate it with an acid (such as vinegar) to find the strength of it.  The pH indicator would also be useful during the soapmaking process to check the progress of the saponification reaction.

Let's take a look at each of those techniques in more detail.

To make soap, we normally use a ratio of something like 2.89 oz NaOH to 7.87 oz water, which works out to about 26.9 wt% NaOH.  According to the above calculator, that should give us a solution density of 1.29 g/mL.  (The analogous numbers for KOH lye would be 4.06 oz KOH to the same amount of water, giving 34.0 wt% KOH, and a density of 1.33 g/mL.)  If we take an egg density of 1.1 g/mL, we can calculate the amount of water that should be displaced by the egg if we know the volume of it.

A typical large egg has a mass of 57 g, corresponding to a volume of 51.8 mL.  Buoyancy dictates that the egg should displace 57 g of the lye solution, which will correspond to a volume less than 51.8 mL if the lye solution is more dense than the egg (which it should be if the egg is floating). As an approximation, we can find an equation for an egg and make a graph to see how much of the egg should be above the water for a quarter-sized interface.

The egg equation came from here, but we normalized it to match the dimensions of an actual egg.  We assumed that an egg was sufficiently symmetrical to use a 2-D projection and calculate areas instead of using a 3-D model and calculating volumes.  In reality, the egg will sit with the skinny end slightly lower in the water since the air pocket is toward the flatter end.  In any case, leaving an area the size of a quarter above the surface would require a lye density of 1.13 g/mL, which is considerably less dense than our standard recipe, which has a density closer to 1.3 g/mL.  If the egg were a little less dense (toward the 1.03 g/mL end), it would sit higher.  As a point of reference, a potato has a density near 1.09 g/mL, in the same range as an egg.

This is a real egg in our standard lye solution (using NaOH).  The solution is yellow because we were testing pH indicators with it (described below).  The real egg looks not too far off of the graphical one, but there are more precise ways to test the lye's strength. 

For example, using data found here (and their related NaOH calculator), we can make a correlation, measure the density of the lye directly, and use the correlation to calculate the concentration.  It would help to have a digital scale and a graduated cylinder, but you can probably get at least as close as the egg/potato method with an old spring-loaded scale and a measuring cup.  We dripped a small batch of lye recently and were doing tests with it, but accidentally spilled it in the kitchen sink before we could test this method.  For lye dripped from ashes, use the KOH equation.  Note that if our solution density is 1.3 g/mL, our lye concentration (as KOH) is about 34 wt%, or 5.2 molar.  This density method will be our favorite lye strength test going forward.

Another way to test the strength is with a pH indicator.  One natural pH indicator is cabbage juice, which contains anthocyanidin pigments.  (As an aside, we noticed similar color changes in elderberry juice and wondered why; elderberries have a similar set of pigments.)  These pigments change structure as the pH of a solution changes, with each structure having a different color.  See here for more info.

The pigment structures of the cabbage anthocyanidins look something like this, with the different colors as shown.  Part of the reason the change from red to purple happens over such a wide pH range is the colorless intermediate.  Similarly, the yellow compound starts to form at pH > 8, but doesn't become the dominant form of the molecule until much higher pH (the presence of both yellow and blue make the solution green, kind of like a Ziploc bag).  The "R" groups are glucosides (i.e. substituted glucose molecules).  Sources for this figure came from here, here, and here.  If you took note of the concentrations above (i.e., that our standard soap recipe calls for 5.2 molar lye) and you are familiar with the pH scale, you might realize that there's a bit of a problem here.  That is, our lye should be at pH 14.7, but our indicator will be yellow at every pH > 11.

Fortunately, we can dilute a small, representative portion of the lye to bring it into the pH range where the indicator is effective.  On the far left in this picture is an undiluted lye solution we dripped from some wood ashes a few weeks back; it's yellow, which means the pH is at least 11.  Since pH is measured on a log scale, diluting by a factor of 10 (conveniently 1 teaspoon solution plus three tablespoons water) should decrease the solution pH by one unit (assuming the water is actually neutral).  On the first dilution, the solution is already green!  That means the undiluted solution was not much over pH 11.  The further dilutions (using one teaspoon of the first dilution plus three tablespoons water, etc.) are consistent with that conclusion, looking similar to pH 9 and pH 7-8  solutions above.  The upshot of this technique is basically (heh) that if the lye is concentrated enough for soapmaking, it should take at least four 1:10 dilution steps to show a color other than yellow.  Alternatively, that means that we should concentrate our lye solution by a factor of 1000 before using it to make soap.  Unfortunately, we only made around a quart to begin with, so we'll only be left with a few drops at the end--not enough to do much with (even dissolve a feather, which was another test of lye strength we were going to try).

Another approach would be to titrate the lye with an acid, and figure out how much acid we needed to observe a color change.  Maybe that will be the subject of a future post.

Guess we'll just have to dry it down with waste heat from the oven (after baking bread or something) and store it in a jar until we can make some more!

Also, in case you're interested, here's how we made the pH indicator solution.  We chopped about a third of a cabbage to give around four cups chopped cabbage.

Then we poured about two cups boiling water onto the cabbage and let it steep for about two hours.

Then we strained out the cabbage (and made coleslaw!), leaving this dark purple-colored liquid.  We add about a teaspoon of this 'cabbage tea' to a cup of liquid to test the pH. It's a little-known fact that a hot jar of this liquid was the inspiration for both the band name 'Deep Purple' and their hit single 'Smoke on the Water.'  (Don't bother looking that up.)

Have you dripped lye from wood ashes?  What did you use it for?  How did you test the strength?  Let us know in the comments section below!

Thursday, February 6, 2014

Historical Lye Making, Part 1

One thing that's not done as much anymore as it should be is making lye on the homestead.  A major contributor to this phenomenon is likely the abundant scary stories and mystique of danger surrounding lye because of some horrible accidents in the past and a general fear of the unfamiliar.  This isn't to say that lye isn't dangerous--it certainly deserves a healthy respect and some reasonable precautions--but, like most things, having an awareness of the properties and dangers is a better approach than running away screaming or cowering in the corner like a congressman.

Ok so, newly emboldened about the utility of lye, let's take a look at why you would want to make your own.  Other than not having to buy an ingredient for your soap-making days, starting with a potassium-based lye instead of a sodium-based one (typically what's available commercially) makes it easier to recycle the soap as part of your graywater scheme since you don't have to worry about sodium buildup.  (Plants need more potassium than sodium.)   In addition to soapmaking, you'll save on ingredients for your homemade drain cleaner, biodiesel (if you get really good at making lye), and lutefisk recipes.

Back in the olden days, when soap making was a standard activity on the homestead, the source of lye was normally wood ashes.  (Even back then, folks knew that grass ashes (e.g., from corn cobs) gave more lye than wood ashes, but no one burned grass in significant quantities.)  The goal was to leach the soluble lye, mostly potassium hydroxide (KOH) in this case, out of the wood ashes, leaving the insoluble parts behind and obtaining a concentrated lye solution.  More generally, however, wood ashes were leached to collect potash: an umbrella term for soluble potassium salts, which could contain potassium hydroxide (KOH), potassium carbonate (K2CO3), potassium chloride (KCl), etc.  The potash was commonly evaporated to dryness and sold as fertilizer when it wasn't used to make lye for applications around the homestead.  And, as with most old homesteading practices, there is an interesting confluence (to us, anyway) of chemistry and history around the lye-leaching process.

Traditional lore says that lye should be leached from hardwood ashes, especially hickory. The reason hardwoods, and especially hickory, should be the best has puzzled us for a long time, since modern methods suggest that softwoods contain no less potassium than hardwoods, at least inherently.  However, old sources also show some data confirming that indeed, less potash is obtained from softwood ashes than hardwood ashes.  Why should that be the case?  We can think of two possible (but contradicting) explanations, neither of which we can find confirmation for.

First, many sources assert that softwoods contain more resins (although we haven't been able to find any quantitative measurements), and thus burn hotter than hardwoods.  The modern source linked above shows that ashes from wood combusted at temperatures above 900 °C lose a significant amount of potassium to evaporation.   Thus, if softwoods burn at 950 °C and hardwoods at 700 °C, softwood ash would likely contain less potassium than hardwood ash.  However, 900 °C is a very high temperature, especially for the open-air fires common before the turn of the last century.

We think it's more likely that softwoods don't burn as cleanly, and more of the inherent potassium remains locked up in the incompletely burned remains.  Some experimental evidence from the period suggests that leach-resistant potassium can indeed be found in incompletely burned softwoods.  (On the other hand, that may mean that softwood biochar is more beneficial for the garden than hardwood biochar as a slow-release potassium fertilizer.)

In any case, it seems legitimate that hardwood ashes are preferable to softwood ashes for making lye, and a clean-burning, fairly hot fire (but less than 900 °C) is the best way to get those ashes.

Also, some old lye recipes call for adding lime or slaked lime to the ash-leaching barrel.  The reason for this addition is clear:  in water, lime (calcium oxide, CaO) becomes slaked lime (calcium hydroxide, Ca(OH)2), which reacts with potassium salts, such as potassium carbonate (K2CO3) to form calcium carbonate (CaCO3) and potassium hydroxide (KOH, the lye we want!).  Depending on conditions, however, the majority of potassium may be leached as the hydroxide anyway, so the lime may only give an incremental increase in lye yield.  Many lye makers don't bother with the lime and still make fine soap, so it seems that the lime must be optional.  For fancy-pants lye making only, if you will.

Additionally, lye leached in traditional ways often times comes out transparent-ish, but very brown-colored.  The reason is that the layers in a lye-leaching bucket normally included a layer of sticks, a layer of straw, and then the ashes.  The lye leached from the ashes can start to decompose the straw and/or sticks, which yield the brown-colored compounds (primarily from solubilized lignin components).  Leaching the lye through a different material, like a tightly-woven t-shirt (multiple layers), or leaching through the straw so many times that all the brown parts are dissolved, would probably yield a clear lye solution.

Finally, many sources indicate that lye should be leached from ashes using distilled (or rain, or soft) water.  For leaching lye per se, water hardness shouldn't make much difference (see paragraph above about adding lime), but if you plan to make soap from the lye down the road, it will be beneficial to not have the hardness in the water.  The cations in hard water are divalent (+2 charge), which means they will take on two soap molecules, become essentially nonpolar, and precipitate out of the aqueous solution, almost exactly like a Dementor eating someone's soul (if one soul = two soap molecules).

The setup for a lye-dripping (leaching) trough, as described in several old books.  It could also be a barrel with a plug in it.  Don't forget to put a bucket under the arrow, or your lye will run out onto the ground.  For other setups, see here, here, and here.

 After leaching the lye, it should be tested for strength.  There were a number of traditional methods, including floating eggs or potatoes, dissolving feathers, and making sure it tastes incredibly bitter.  (Don't try the last one).  Modern techniques include testing the pH and/or measuring the density (the latter being an updated version of the egg or potato test). 

Since this post is already very long, we'll wrap it up here.  Check back on Sunday for Part 2, featuring lots of pretty colors!

In the meantime, have you dripped your own lye from ashes?  What did your setup look like?  Do you have a better idea why hardwoods are better than softwoods for making lye from the ashes?  Let us know in the comments section below!

Sunday, February 2, 2014

Coconut Oil Replacement for Temperate Climates

It seems that a lot of recipes for homemade hygiene products call for coconut oil as a primary ingredient.  And why not?  Coconut oil is touted as having numerous benefits, which may or may not be legit. (Many of the benefits may be topical rather than dietary.)  We're not much into beauty products, but occasionally we discover a need for some type of 'cosmetic' product, such as deodorant for when someone we actually like invites us to an event in the public sphere.  In the past, we have incorporated coconut oil into some of our homemade hygiene items, mainly as a high-melting binder for something like deodorant.  However, we've found two problems with this situation.  First, the coconut oil, although higher-melting than many other oils, sometimes melts in the summer heat.  Second, we have no intention of living in the coconut's natural habitat (coastal areas within ~26° latitude of the equator), which means it would be very difficult to produce our own coconut oil on the homestead.

However, we do (or more precisely, will) have the capability to produce beeswax and vegetable oils (e.g., canola or sunflower oil), which we hypothesized we might be able to combine in certain proportions to produce a mixed-lipid substance with a tunable melting point.  The first thing we had to do was build something to measure the melting points.  Oh boy, a project!

We wanted to use a spare piece of leftover metal from the 90° electrical conduit punch-out elbows we used for the row cover we built last fall, but the Home Depot spec sheet said the pieces were either cast zinc or galvanized steel. We were a little nervous about heating zinc (it turns out it would have been fine for this application anyway), but when we held the pieces, they sure didn't feel dense enough to be zinc or steel (which have densities of 7.2 and 7.8 g/cm3, respectively).  We suspected they might be aluminum, so we converted an empty spice jar into a makeshift graduated cylinder (sort of like a really nerdy MacGyver), then used the old displacement principle to calculate a density of about 2.7 g/cm3--suspiciously close to that of aluminum.  No zinc fume worries, and good thermal conductivity--yay, science! (And Home Depot shoppers be warned...)

Then we built a little contraption out of scrap wood to turn our aluminum piece and our wood burning tool into a melting point apparatus.  She ain't purdy, but she sure is sturdy!

We drilled a partial hole in the center of the bottom in which to nest the wood burner, and two holes equidistant from the center: one for a small piece of whatever solid we're melting and one for a thermocouple or thermometer.   This setup heats surprisingly quickly, so we had to serve as our own PID controller by plugging in and unplugging the wood burner.  It would be way easier to add a potentiometer between the wood burner and the wall outlet (something like this guy did), if we had one on hand and wanted to precisely control the heating rate.

The next step is to put a small chunk of the wax or wax/oil mixture in the one hole, hold the thermocouple in the other hole, and heat 'er up!  Keep heating until...
....the wax melts!  We got 142 °F as the melting point for the pure beeswax, which is pretty close to the normal range.  The aluminum plate cools down pretty quickly, so we can record the temperature at which it re-solidifies also, and do multiple melts to get an average.  (Since we know the approximate melting point from the first melt, we can unplug the wood burner sooner in subsequent replicates to approach the melting point more slowly--maybe even as slow as a real melting point apparatus would!)

With the instrument and methodology validated, we can finally pursue our goal of finding a beeswax/oil blend with the melting temperature we want.  We mixed up combinations of 80%, 60%, 40%, and 20% beeswax in canola oil (by volume) as our standards.

Then we made sure they were good and melted in the microwave.  We stirred the melt to mix everything well, then set them outside to freeze.  If the air outside is going to be cold, we might as well make use of it!

The 20-80% beeswax standards all had a pretty high melting point (e.g., the 20% mix melted at 118 °F), so we added a 5% beeswax mix to the curve.  It looked kind of like runny Vaseline, and seemed to cross over to the liquid side around 70 °F.  That's lower than the melting temperature of coconut oil (which we measured at 79 °F, compared to an internet value of 77 °F), and is probably too soft for making deodorant.  The 20% mix seems like it might be about right.

Here's the data all together.  The point at the far left (pure canola oil) is from here since the air outside wasn't quite cold enough to freeze it (nor was our freezer, for some reason).  Naturally, the curve would look different if other oils were added into the mix, but we'd wager that oils with a similar fatty acid profile to canola oil would give similar results.  The line is a fit to the equation shown, which has no physical meaning, as far as we know, but seems to fit the data well.  (Hooray for empiricism!)  Physical chemistry students: you might be able to publish a paper on the theory behind it.

Have you mixed beeswax with other oils for your own homestead hygiene?  What's your favorite combination?  Let us know in the comments section below!