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Bubbles in resin


#1

One trick we use in eliminating bubbles in resin is after mixing to
place the container in the vacuum and vacuum at full for several
minutes. This most always gives a clear resin even in large amounts.
Frank Johnston


#2
           One trick we use in eliminating bubbles in resin is
after mixing to place the container in the vacuum and vacuum at full
for several minutes. This most always gives a clear resin even in
large amounts. Frank Johnston 

Okay, I’m going to own up to my commitment to be open and sharing on
this forum and tell you my secret for getting my colored and clear
enamels to set bubble free.

I use Durenamel colored resins in sterling for a line of production
jewelry I make. I had a lot of problems with bubbles and ran
experiments and took notes until I figured it out. Here’s the
problem I think most people are not aware of. I tried vacuming after
mixing, after applying, all to no avail. What I discovered is that
when you heat cure the resin, there are gasses in the metal that
expand and rise through the resin. At some point, the resin becomes
viscous enough to trap them. What I found was that the Durenamel,
and I expect this is true of other resins, will cure without heat,
but it takes much longer. I found that when I left the resin in the
cavity to sit until it was getting quite hard (a process that
usually took overnight), then subjected it to the 150 degree baking
for the appropriate time, I would end up with a product without
bubbles. This problem is perticularly present when working with
sterling, as the typical casting is always somewhat porous, unless
you’re casting in a neutral gas atmosphere. Typically, when the pros
enamel on sterling, they have some process (which I know nothing
about) to “de-gas” the sterling. Now another trick I like when I’m
using clear epoxy is extrude out and mix the 2 components on a small
sheet of metal (aluminum works nicely). Then I gently heat the
metal from underneath. The expoxy will begin to become very fluid
and the bubbles will rise to the surface easily and disperse. Apply
it quickly, pouring it off the sheet into where it’s needed, because
now it is going to set in a fraction of the time, so you don’t have
much time to get it into your piece. I suppose this could compromise
the quality of the expoxy, but I’m not sure. Sometimes, I will soot
the metal with a torch using only gas, no oxygen. Then when I mix the
epoxy, I stir in the black soot and get an extremely black epoxy.
When you warm it, it becomes very liquid and flows in filling fine
cracks and crevices.

David L. Huffman


#3
    One trick we use in eliminating bubbles in resin is after
mixing to place the container in the vacuum and vacuum at full for
several minutes. This most always gives a clear resin even in large
amounts. Frank Johnston 

And if you REALLY want it bubble free, after vacuuming it, pour it
in carefully then put it under pressure in a pressure chamber of
some type. It doesn’t have to be real high pressure, 10 15 pounds
will go a long way in elimination the bubbles. Just be REAL careful
with the pressure container as 10 - 15 pounds of air pressure can
be dangerous if things get away (the container lets loose) but it
really shouldn’t be a huge worry. Hone pressure canners work at 15
pounds and can make a good cheap pressure vessel.

John Dach


#4

After more experimentation I realized that, as some have pointed
out, it was the heat causing the bubbles – once I gave up on the
skillet-warming method and went for the slower cure time I had very
little bubble trouble. Have yet to try the clamp lamp/heat box, but
hope to do so soon.

My next major problem is DUST! I pour the resin, pick out any dust
flecks with a pin, and cover the pieces until cured. Still I find
dust! I’m using clear resin so it is noticable (at least to me!) and
it’s driving me mad. Any tips?

I also made the dumb mistake of trying to buff out the surface dust
speck on a piece and ended up with a big mess…first the ultra-fine
(light green) 3M bristle brush dulled the surface, then the linen
buff with compound melted it. Lovely!

-Jessica in nippy SF, about to transition over to the digest for the
holidays…


#5

Hi Jessica,

Here is how Betty Heald taught me to finish epoxy. Use 80 grit on
belt sander or hand sand. Do not let pieces get hot or they will
fog, wrinkle and/ or melt. Move to 400 then 600 then 0000 steel
wool. To polish use standard soft felt or 42 ply muslin buff @ 3450
rpm use plastic compound or ZAM. DO NOT USE ROUGE(her emphasis).
Careful not to press to hard against buffing wheel…more melting and
fogging will ensue(experience talking here). I have experimented with
the 3m radial bristles and get good results but they can really dig
in if one is not careful. They will dull the surface just like they
dull the surface of metal. The steel wool followed by the Zam will
polish everything up just fine. I have experimented with the
microabrasive papers with moderate success. It is quicker to use
band sander or 3m bristles and zam in my opinion.