[papercreters] Borax, Boric Acid, Borates, Lime Quandry

Borax Quandry...

I've been trying to locate a good source for bulk borax, and being that I don't live in a large metro area, I've turned to the Internet.  I initially thought I could just buy bulk borax like either Three Elephant Borax or 20 Mule Team borax mentioned by members of the group, and go about my merry papercrete mixing way.  But what I discovered is that there is a variety of borates (see links below), and the choice is just not apparent to me.  I'm hoping someone in the group can help me answer a few questions, based on their experience or their knowledge of chemistry (or both!):

Q. Which borate will have the best mix of insecticidal, fungicidal, pesticidal, and fire resistant qualities, while remaining cost effective?
        - some more regulated borates are expensive because of their primary intended use

Q. Which borate will complement and work best with the cement hydration process, from an acid/alkaline perspective?
        - boric acid is, acidic, while the salts are primarily alkaline -- will too acid or too alkaline weaken the mix?

Q. What is the optimal dosage, and best way to maximize effectiveness and minimize loss in water run off?
        - is dissolving in water prior to mixing far superior or just marginally better than just adding it to the mixer?
        - how much is too much and how much is too little?  (too much washes away, not enough doesn't do anything)
        - While the solubility ranges from around 3% to 9% at room temperature, is solubility a good indicator of the optimal amount to use?

Q. I expect that increasing the portland cement amount will result in a corresponding decrease in the need for borax -- but where is the cross-over point?

Q. Would Lime achieve the same fungicidal/pesticidal/insecticidal results at borax, but perhaps at a lower cost and in a more environmentally friendly way?


In the spirit of wanting to create uniform mix designs that have been field proven, I don't think it is enough to just say "add a few pounds of borax to kill the insects, stop the mold, and retard fire."   Maybe this is adequate for many, but what if you build a papercrete house based on heresay, only to find out that the amount of borax you used was insufficient, or the way you included it in your mix design made it ineffective (such as washing it away in water run off)?  Test, test, test!

I do not mean to question anyone's recommendation based on what worked for them in their unique situation, I'm just thinking a more thorough understanding of the chemistry of mix design, coupled with specific tests, would result in helping people make mix design choices based on their unique situations, with somewhat predictable results.  Any chemists out there??

For example, at what concentration of borax does it cross over from being ineffective to being effective? (for insects, mold, fire...)  I suppose the best way to find out is to design a series of experiments and find out.  Based on my conversation with Searles Valley Mineral, if the papercrete group made a professional approach to them, as a fledgling industry, they may be willing to provide some lab assistance (it would be in their interest to tap a new market).

Part of what makes for a good product is, as we all know, a good recipe, or mix design.  Making the transition from "experimental" to "code approved" will probably require a certain amount of lab testing and experimentation, but I assume that is one of the focuses of the Code Group.  Perhaps more importantly, though, thorough testing and understanding of the chemistry of additives (such as borax, fly ash, pozzalons, latex paint, etc.).

While there may be as many different papercrete mix designs as there are papercreters, answering some of the above questions would help everyone achieve their mix design objectives in a more intentional way, like they do in the cement industry.

For me personally, it makes me realize that I have much more testing I need to do before I can standardize on a mix design for my situation.  So any help on the above questions will be most welcome!

warmest regards,

Eric Randall
Fairfield, Iowa



The manufacturer of Three Elephant Borax is Searles Valley Minerals Company: http://svminerals.com/SVM/Borax.html

They mine/refine three different boraxes, as well as boric acid,

• Pyrobor®  - Anhydrous borax (Na₂B₄O₇)
• VBor®  - Borax pentahydrate (Na₂B₄O₇·5H₂O)
• Borax decahydrate (Na₂B₄O₇·10H₂O)

The other primary borax provider is Rio Tinto Borax (previously U.S. Borax): http://borax.com/ which makes
"20 Mule Team" borax.  Rio Tinto also makes a wide variety of borates: http://borax.com/products1.html.  This is a list of borates available for sale: http://borax.com/leadtimes/distributors9a.html

borates in wood treatment: http://borax.com/wood/products2.html

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