Chiyogami Paper Executive Clicker

We had a massive thunderstorm roll over the weekend which meant that I was workshop bound again

Did some more castings, this is a Chiyogami Paper Executive Clicker.

Does anyone know how I can prevent bubbles from appearing just as the resin starts to gell? When the resin is still liquid - no bubbles, just as it starts to gell - bubbles start to appear. Lost about 30% of the castings because of the bubbles.

I can't use a pressure or vacuum pot because I am using the resin saver molds.

Suggestions greatly appreciated.

Timberbits

Attachment 307712

David not done the paper ones as yet (soon though) hehe, sounds like a reaction to the paper ,I usually give blanks of this nature a light spray of clear acrylic and allow to dry, this gives a prep coat of acrylic and can help with putting "like on like" so no adverse reaction , but the expert on these is Sam ,so may have better advise :) Cheers ~ John

David as per what John has said I usually give my paper 2-3 coats of WOP prior to casting

Quote:

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Originally Posted by timberbits

Does anyone know how I can prevent bubbles from appearing just as the resin starts to gell? When the resin is still liquid - no bubbles, just as it starts to gell - bubbles start to appear. Lost about 30% of the castings because of the bubbles.

I can't use a pressure or vacuum pot because I am using the resin saver molds.

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You can use pressure with the ResinSaver (but not vacuum) but not much. I've told
people not to use pressure because there is tendency to think that if a little is good,
then a lot must be better. Clearly that doesn't work with the molds.
But you don't NEED a lot of pressure.

If a flimsy plastic bottle can keep all of that carbon dioxide inside ginger ale with only
15-18 psi, it's easy to see that you don't need much for casting.

BUT .. casting paper is tricky. Pressure isn't what is needed, but as others mentioned,
you need a good cured surface. (and don't feel bad.. I've thrown away hundreds of
paper castings before I figured out what I was doing wrong)

The paper is full of air. This is why some people would coat the paper with uncured
resin before casting. The resin displaces the air in the paper. You can also do it with
polyurethane, CA etc. It comes out of the paper as the resin starts to gel because
as the resin heats, the air expands. So those microscopic bubbles now grow so large
that they won't stay inside the paper anymore.

So ..get something else into the paper to move the air out. But MOST IMPORTANT is
to let it cure. Not just dry, let it CURE. Otherwise, you can get a reaction with the resin,
and that creates a whole different type of air bubble. You might need to cure them for
several days or even weeks, depending on what you used. (lacquer dries fast, but takes
weeks to cure)

disclaimer: I designed the ResinSaver molds, but turned it over to Wolftat a couple
of years ago. So I'm no longer involved with them.

I use 40-45 PSI when casting with Resin Save molds with no problems.
I measure the distance between the tits in the mold and turn an insert that fits tight inside the brass tube I'm going to use.
This way there is no air trapped inside the brass tube and no PR can get inside the brass tube.
Works great for me.

Les

Thanks for the suggestions guys.

I already put a coat of CA on the paper before I cast, might put another 2 or 3 coats of CA to fully seal the paper before I cast and see if that makes a difference.

Also, I will reduce the amount of hardener by half to see if that makes a difference. I only cast once a day or every two days so speed is not of the essence.

Quote:

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Originally Posted by gawdelpus

David not done the paper ones as yet (soon though) hehe, sounds like a reaction to the paper ,I usually give blanks of this nature a light spray of clear acrylic and allow to dry, this gives a prep coat of acrylic and can help with putting "like on like" so no adverse reaction , but the expert on these is Sam ,so may have better advise :) Cheers ~ John

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Hey Gawdelpus,

Am intrigued - Is it difficult to spray acrylic - is it done with a simple $2 plastic bottle or a big fancy spray gun with compressed air - and what is meant by "acrylic" is it the same stuff as the casting resin or something else ?

Bill

I've been using hairspray (the cheap stuff) as a fixative on my hand-painted clear casting tubes. I'm sure I read or heard this on the forum.

Would this seal on paper ?

Quote:

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Originally Posted by steamingbill

Hey Gawdelpus,

Am intrigued - Is it difficult to spray acrylic - is it done with a simple $2 plastic bottle or a big fancy spray gun with compressed air - and what is meant by "acrylic" is it the same stuff as the casting resin or something else ?

Bill

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Bill ,I use a pressure pack can of clear acrylic , I think it is the same as they spray on cars to seal them after color coats, not hard at all to spray ,I get mine from Super cheap autos, they keep changing brands ,but I think Septone is the main one I use. Cheers ~ John