No matter what sort of container I store my boric acid/alcohol
solution in, it gradually re-crystalizes on the rim of the container
and cap, making it increasingly harder and harder to seal the jar
(and increasing the rate at which the alcohol evaporates.) I finally
bit the bullet and purchased an expensive wide-mouthed heavy glass
jar and lid with ground glass edges from Rio, of the sort often used
by watchmakers. In theory, the ground glass of the jar rim and lid
seal so tightly as to prevent evaporation, and for that reason, this
is often seen on perfume vials and vinegar cruits. So, did my
expensive purchase solve the “blooming” of boric acid crystals? Nope
– I did just as well with a mustard jar. Not only is this
frustrating and wasteful, I’m also not thrilled to have this
volatile, toxic stuff evaporating out into my studio.
So, my friends, how do you store your boric acid/alcohol mix and how
do you resolve this problem?
Many thanks,
Susannah Ravenswing
Jewels of the Spirit
Germanton, NC 27019
Yes, we out here in the SF Bay area have the same problem… I use
recycled pickle or salsa jars and keep the lids clean… This means
periodically cleaning them off and also the edge of the jar. Since
my bench is near an open window, the fumes mostly go directly
outside. I haven’t found any better solution yet. Perhaps a
rubberized canning jar( the European style), where the lid opens and
closes with a rubber seal might do the trick. Since I am almost
halfway thru the jam making season and have one of these jars
leftover, I may give it a try-and if I have success,I’ll let everyone
know. But for now,we just use the food jars with wide rims and clean
them off…
I’ve used a glass jar with ground stopper for decades. You’re right,
the boric acid builds up as the alcohol evaporates. My solution
which has worked for several months is to use the tinyest bit of
silicone grease to coat the ground glass areas. Where can you get
silicone grease? I got mine from the chemistry glass shop on campus.
I suspect any university or college with a chemistry lab will have
some and you only need a little dab.
So, did my expensive purchase solve the "blooming" of boric acid
crystals? Nope
Here are a few suggestions that may help to control the growing
crystal of borax that decorates the lid of the alcohol/borax
container.
I mix small amounts of the solution, and freshen it up as needed. I
use smaller amounts of borax, so the solution is not too thick, and
repeat the application several times to build up several thinner
layers which seem to coat the piece better anyway. (My solutions are
saturated, but without too much excess laying on the bottom of the
jar.) When I get ready to solder, I take a few seconds to knock some
of the residue from the top back into the jar, (since I do it
regularly, it’s a relatively thin layer) and remix it into the
solution. I also wash out the top of the container periodically,
since it’s the inside lip of the cover which tends to build up some
crystallization, and keeps the seal from being tight. Lids that have
a thicker plastic seal work better than those that don’t. Hope this
helps.
I store my boric acid mix in a straight-sided glass jar with a wide
mouth. It is a recycled food jar with a metal lid that has a ring of
plastic on the lid where it contacts the glass jar lip. It seals as
well as anything else I’ve found. My method of not losing too much
alcohol is to not put much in there! I just have a little bit of
boric acid with a small splash of alcohol in the jar. I even have to
tip the jar sometimes to get enough liquid to work with. This way I
don’t lose too much from evaproation on any one day.
You can re-use the crystals that appear around the rim of the jar.
Just wipe them off with an alcohol-soaked brush to get them back into
solution.
Perhaps a rubberized canning jar (the European style), where the
lid opens and closes with a rubber seal might do the trick.
I have been using one of these for about a year. It worked well at
first, but the crystalized boric acid and/or the alcohol has
stiffened the rubber (actually, clear… silicone?) sealer so that
now it isn’t tight and the alcohol evaporates pretty fast.
The best thing I’ve found for this is a small plastic “specimen
container” (like those used for clean-catch urine collection) -
holds about 1/2 c total and has a lid that screws on tightly. They
are impermeable and very clear (not clouded) plastic, and I recall
paying about $.20 each for them at a surplus store. I keep a supply
on hand and use them for on-the-worktable flux (keeps my big
container from being opened too much), ochre, alcohol/boric, etc.
They’re wonderful and take well to a sharpie for labelling.