Wednesday, August 1, 2007

[papercreters] Borax

There seems to be a dearth of recent research on the boric acid/borax combination.   Perhaps I should not be so hasty in criticizing the 1990 paper for keeping their solution hidden and not citing previous research.   This borate combination has been used in homespun fire prevention for many years.   For example there is the following recipe:
"Mix together nine ounces 20 Mule Team Borax and four ounces boric acid in one gallon water."
 
Boric acid is not very soluble in tap water (~6%).   As very mildly acidic it would only have a very small effect on the alkaline cement reaction.   Lack of solubility means that the water in a papercrete mix would function primarily as a dispersal medium.   Thus it is an open question how much of the boric acid would be deposited on the paper and how much would be drained away by the water.
 
In contrast to boric acid, I am now very hopeful about the possibilities of using borax in a PC mix.   Here are some interesting facts:  Borax is a salt of boron and has been described as being, in essence, half-neutralized boric acid.   As opposed to the insolubility of boric acid, borax is very soluble in water and forms an alkaline, antiseptic solution that is used as a water softener, disinfectant, detergent and welding flux.  In solution (like your washing machine) it is an alkaline buffer, which means it would help the cemeneous reaction in a PC mix.   It would also promote the solubility of ingredients in PC. 
 
Borax's fire retardant properties may be due to the fact that when it is heated above 62C borax puffs up to many times its original size in a voluminous, spongy mass. 
 
Historical tidbits:  many ancient people found valuable uses for borax. The Egyptians used borax in mummification while the Romans used it for glass making. Marco Polo's caravans transported it from Tibet to Europe in the 13th century.   Borax was a rare commodity until lake bed deposits were found in California in the 1850s. The most famous commercial borax mining operations were located in Death Valley in California in the 1880s. Borax was recovered by dissolving "cotton balls" made up of borate minerals in boiling water. As the solution cooled the borax precipitated out. To get the borax to market was a 165 mile journey through the hot desert to the nearest railroad. Up to ten tons of borax was carried on giant wagons that were pulled by teams of 18 mules and 2 draft horses - the famous "20-mule teams." These teams averaged two miles an hour; as a result the round trip took 30 days to complete.
 
Neal
 

----- Original Message -----
Sent: Wednesday, August 01, 2007 12:20 PM
Subject: Re: [papercreters] Re: PC fire resistance

Duane,
 
There article you reference is 17 years old and contains some theories (like the char coating) that have been shown to be false recently, at least in the 2004 paper that I used.   The main problem with the article is that it uses an unknown and unnamed commercial boric acid/borax preparation.   Since we don't know the name of this, we don't know whether it is water based or how the two ingredients were combined.   Questionable research.  It may be that as SG or someone pointed out that mixing boric acid with borax with water may not be a good way to combine these two ingredients, especially for the necessary cement reaction in PC.   It would be interesting to look at the ingredients of currently available fire retardation products now.
 
The paper does have a brief (and inadequate) description of the fire tube test:
 
In the fire tube test, the sample stick is inserted reside(sic) a 38 in.- (1-m-) long, 3-in.- (76-mm-) diameter galvanized iron tube. A Bunson burner adjusted for a flame height of 11 in (280 mm)
IS used to ignite the bottom end of the stick. Weight loss of the stick is monitored Via a balance mechanism. The burner is removed
after 4 rnin. The final percentage of weight loss is used as the main criterion for comparison.
 
Neal
 
 
----- Original Message -----
From: mdumiller
Sent: Wednesday, August 01, 2007 8:38 AM
Subject: [papercreters] Re: PC fire resistance

I followed some advice in the article "The role of boron in
flame-retardant treatments" which notes that :

"Borax tends to reduce flame spread but can promote smoldering or
glowing, On the other hand, boric acid suppresses smoldering but has
little effect on flame spread. Therefore, these compounds are normally
used together."

the other stat which I used was:
"We estimated that loading levels of at least 7.5 percent add-on level
of borax-boric acid are needed for southern Pine to meet the ASTM E 84
class I requirement."

The article I should have referenced was
http://www.fpl.fs.fed.us/documnts/pdf1990/levan90a.pdf

I based my percentages on the weight of the fuel (the paper part) so
my add-on was 8% of the paper weight. I used the 1:1:1 ratio of
paper:portland:sand based on it being in the "middle" of a lot of the
recipes I saw, including at livinginpaper.com where they listed a
1 : 1.5 : 1 mix as a "starting point". I actually had some lime in
the mix too, so my mineral portion was probably closer to 1 1/3
mineral. One thing I did not do, and should have, was to pre-dissolve
the borax in hot water, this might have made a big difference. From
my experience, Borax does not dissolve very well in cold water.

SLURRYGUY thanks for your ongoing encouragement and advice !! I'll
put more portland into the mix!!

A point I had hoped to make is that, IMHO, if the mix is too lean, and
if proper fire-retardants are not added to the mix, the final product
is a death-trap if it's something you will live in. The recipes being
presented don't clearly indicate the critical issue here. There's a
good reason that houses use non-combustible drywall over the
combustible wood studs. If you intend to used PC for a house, you
should pay particular attention to the mix to achieve a product that
does not burn, or coat the surface with a plaster-type component to
prevent surface combustion. In our excitement to further the use of a
green building material, it is easy to forget that the primary
ingredient in these PC buildings is the same one we use to start a
roaring camp fire.

I'll try a similar test with more portland/mineral and pre-dissolved
borax/boric acid as per the paper referenced above, and, if anyone is
interested am happy to share the results. I've noticed other PC
websites are charging for their research, and sincerely appreciate the
open-source approach of this incredible forum. - Duane

--- In papercreters@yahoogroups.com, "Neal Chabot" <sire@...> wrote:
>
> Duane may be using the words boric acid and borax synonymously.
The Forest Service research (2004 paper) that Duane implicitly
references does not use borax in the tests for fire retardation. It
uses boric acid in about a 3.5% concentration by weight. It also
uses a chemical called guanylurea phosphate (GUP) by itself and in
combination with boric acid. That combination (7.5% total weight)
gave the best fire retardation properties, so it may be worth
consideration for use in PC when maximum fire retardation is important.
>
> Neal
>
> ----- Original Message -----
> From: slurryguy
> To: papercreters@yahoogroups.com
> Sent: Tuesday, July 31, 2007 8:04 PM
> Subject: [papercreters] Re: PC fire resistance
>
>
> Hi Duane,
>
> Your results are close to inline with my experiments, but I don't
> agree with your conclusions. Papercrete can be made such that it
> will not continue to smolder. Please continue to experiment.
>
> I've conducted ALMOST the exact same test you conducted. I didn't
> use any borax in a 1:1:1 paper, portland, sand test mix and obtained
> very similar results.
>
> 2-1 ratio of portand to paper seems to be very close to the point
> where papercrete begins to become non smolder supporting.
>
> All papercrete will char on the surface when exposed to a torch in
> the manner you conducted your test. Higher mineral content mixes
> will not continue to smolder. Also keep in mind that air circulation
> affects the test. If the small embers are fanned sufficiently they
> will tend to smolder hotter and longer.
>
> I'm curious about your logic about using a mixture of both boric acid
> and borax. One is acidic the other is alkaline. It seems they would
> chemically react and form a boric salt and a little (very little)
> extra water. I don't know if boric salt has the same combustion
> retarding properties as plain borax. I also don't know if boric salt
> will penetrate inside the paper fibers the same. 8% borates seems
> very high and should have produced much better results than observed
> in your test. I'm wondering if the acid/alkaline reaction might be
> the reason. Just guessing.
>
> Keep in mind that portland is not the only material that can raise
> the mineral content to bring papercrete's fire resistance up to a
> level that it will not continue to smolder. Clay works very well.
>
> 1:1:1:1 paper, portland, clay, sand with some plain borax will fare
> far far better. It might continue to smolder for a short time, but
> it will not consume the whole sample as you experienced.
>
> Alternatively 2:1:1 portland, paper, sand with plain borax will also
> fare well.
>
> 2:1:3:2 paper, portland, clay, sand with some plain borax will also
> fare well, but will take longer to dry.
>
> I encourage you to keep experimenting and reporting your results.
> The experiment you conducted is not a failure. It's part of the
> learning process.
>
> One more thought. When did you add your borates? My rule of thumb
> is to add the borax to the paper as soon as possible during the
> pulping process. This gives maximum opportunity for it to soak into
> the paper.
>
> (All ratios I listed are BY WEIGHT)
>
> Keep having fun. Keep sharing.
>
> --- In papercreters@yahoogroups.com, "mdumiller" <mdmiller1@>
> wrote:
> >
> > I ran a fairly unscientific but interesting fire-resistance test on
> a
> > PC sample I had made. From what I see, I'm not convinced that PC
> can
> > be made totally fire resistant without a lot of additives
> (increasing
> > its cost to make). My mix included a borax/boric acid mix in a
> > weight ratio equal to what the forest service recommends for making
> > wood more fire-resistant.
> > What was interesting was that the material never at any time as a
> > fuel source produced an open flame, only smoldering. Another fact
> I
> > found interesting was that the block continued to smolder for
> twenty
> > minutes after the propane torch was removed, looking like a piece
> of
> > charcoal from the barbecue grill. I would imagine that doubling
> the
> > portland would slow the smoldering, but I had hoped the borax/boric
> > acid mix would extinguish the block once the torch was removed--but
> > no luck.
> > Some type of integral firestopping might makes sense when PC is
> used
> > in a wall to limit the spread of the smoldering, since ultimately
> the
> > block was consummed. To play it safe, I believe that the wall
> > surface should be coated with a plaster or gypsum product to
> prevent
> > the smoldering from starting. Here is a link to pictures:
> > http://www.domovitae.com/fcrete/pcfire.htm
> >
> > food for thought - Duane.
> >
>

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