After many years of playing with ordinary epoxy and Elmers woodfill, I
have graduated to Bondo :)
Any tips with how best to measure, mix, and handle the material.
The can I bought comes with a measuring cup and talks about using a
1.5" bead per cup.
- Do you mix it all together in the provided cup or do you use
something more disposable?
- How precise do you need to be in measuring out ratios of materials?
- Any tricks for applying and shaping the mixed material? (it seems to be very
- Any way to get a longer work time then 3-5 minutes?
Thanks for the advice
Interesting articl and thanks for the link, but:
- It doesn't really answer any of my specific questions
- It is targeted to body shop repair while I am interested in it more
for *home* repair uses such as filling wood defects, etc.
I still have not found a good googled article addressing my questions
specifically though I found more than I ever wanted to know about body
shop techniques :)
http://tinyurl.com/d3c37 That's the search for "bondo tips techniques
wood repairing". There's plenty of stuff in there about mixing and
The stuff isn't rocket science and you'll find your own preferred
methods of work. I've heard everything from mixing it in a plastic bag
to doing it on a piece of glass. The proportions aren't super
critical. The hardener is a catalyst that causes the filler to harden.
You can vary the properties of the final product by varying the ratio
of the two components in your mixture. A greater proportion of
hardener will make the bondo cure more quickly and be less flexible.
Not enough hardener and it will never harden correctly.
Usually when you're mixing a two-part material with catalyst it's an
exothermic reaction and the heat can be a problem as it speeds up the
reaction. Some people refrigerate the components prior to mixing, but
that makes it tougher to mix and won't buy you a lot of time. In that
situation you should look for another product. Bondo has a lot of
different products and several different hardners. You're not limited
the the stuff you find at your local hardware store, nor to a
is it a true catalyst? if so, it wouldn't be used up in the reaction, so
would eventually cure the entire batch. bondo turns hard in the container,
so one would assume that it would eventually, not "never", harden.
cave creek, az
The operative word, which you omitted in your reply, was correctly. It
will never harden correctly. Never _is_ a long time, but as I've only
been around for a relatively short time (measured in decades), I can't
say for sure either way. ;)
I like to make a puddle of the bondo and then make a smiley face on it
with the hardener. That's about the right amount.
Go to an autobody supply store. The sell plastic mixing boards. They
are easy to clean up with some lacquer thinner as long as you clean it
up quick. Don't ever use cardboard to mix on since it absorbs some rein.
Not very. It just controls how fast it gets hard.
You need to sand with rough sand paper (40 or 80 is what I use) before
you apply it so it will stick. Use the plastic spreaders and press down
firmly so it fills in the cracks and crevices and sticks well. Try to
get smooth coats so you don't have to sand a lot. But you can use a
cheese grater to shape it once it firms up. If you find it too sticky
and clogging your sandpaper then you didn't wait long enough for it to
You can use less hardener but you still won't get a lot of useable
working time. It's best to use several thin coats anyway.
You can also chill the can down in the fridge and chill an old china
plate to mix it on too. That'll slow down the curing of the unspread stuff.
Some random thoughts from my years of using Bondo to fix everything
except a broken heart and the crack of dawn:
Exposed Bondo doesn't hold up very well to water exposure, so if it's
going to be outside or splashed on frequently make sure to give it a
good covering of paint.
If you are using Bondo to fill "holes" or gaps in wood, the adhesion is
not very good. You can improve that a lot by driving in some screws or
nails part way into the wood so their exposed shanks and heads will get
surrounded by the Bondo.
If you need maximum strength, switch to the Bondo with the fiberglass
filler in it. You can also imcrease strength by burying straight or
shaped "reinforcing rods" made out of coat hanger wire. (Use the heavier
On Mon, 12 Sep 2005 21:41:05 GMT, in alt.home.repair blueman
This is insofar as finish, not working time -- and I have always worked with
external spackle, not Bondo, but the same may apply.
If you are doing a woodfill and it is fairly thick and dries slowly enough
to form a not-tacky top "skin" and then cures through, and if you have a
sample of the grained board are repairing then you can mash that into the
spot and transfer a grain impression. I only work on my own house, but I
did that several years back where i had two holes in the siding from a bird
after insects (may have been indicative of another problem but nothing came
of it) and after this little grain impression and the re-painting weathered
in, i could not tell where I had made the repair.
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