New casting oddity????

Signed-In Members Don't See This Ad
Russianwolf

Russianwolf

Member
Joined
Jul 13, 2007
Messages
5,690
Location
Martinsburg, WV, USA.
Here's a pic of a rather unique occurance I had. Prepped everything as usual, Didn't apply a sealer coat over the paint as I have done on other batches. Cast vertically (so as it appears in the pic). Cast at 50psi.

Had these lovely bubbles appear. Now they are tiny and stretch from the edge of the dichro out radially toward the plastic tubing used to cast. They did not try to go up towards the surface. Everything else came out great.

I sent these off to Ed and Dawn and Ed has turned one. Talking to him about it he says once down to pen size you can feel them while turning with the skew, but can't feel them with your finger. :bulgy-eyes: I haven't seen them once turned, maybe Ed will post an after pic.

What do you guys think caused this one? I've since made sure to use the seal coat on the paint and not had a reoccurance.
 

Attachments

  • DicroHairs2.JPG
    DicroHairs2.JPG
    67.9 KB · Views: 473
Signed-In Members Don't See This Ad
Looks like the air was trapped between the tube and the Dichro and the pressure squeezed it out. Don't want to ask about your methods, but maybe try and see if there's something with how you're attaching it. If sealing it is helping I'd stick with it. Those are too cool to have bad casts!
 
Looks more like fracturing than bubbles. Hard to tell from the picture.

Other than sealing, was anything else different than usual? Lower shop temps? Less time under pressure?

Ed
 
definitely not fracturing. The resin is a much slower curing type and I leave them in the pot overnight under pressure.

Nothing else was changed other than the sealant coat.

My first thought was your's John, but the way they are radial instead of trying to head for the surface and came out more hair-like instead of spherical makes me wonder. Ed thinks it must have happened at just the right time in the process to capture them like this. Which again is strange given the slower cure time and that they go under pressure relatively quickly. There isn't much space under the Dichro for trapped air, but anything is possible.

I've got about a dozen cast since that batch ( only 4 came out like this) and narry a issue in the bunch, so I'm not too concerned just curious more than anything else.
 
Mike,
If your using the same set up I am (VisiPak), then I've encountered a similar oddity. I narrowed it down to what I believe was caused by a static charge in the vertical plastic tube.

Blame it on Thomas Edison :biggrin::biggrin::biggrin:
 
I may be understanding things wrong, but if you're thinking there may have been air trapped under the dichro, pressure would have pushed it IN rather than let it come out. What may have happened when the pressure was released? I could see trapped air at that point being able to work out, but unless you dropped the pressure before it was pretty solid, that would surprise me...
 
Druid said:
Mike,
If your using the same set up I am (VisiPak), then I've encountered a similar oddity. I narrowed it down to what I believe was caused by a static charge in the vertical plastic tube.

Blame it on Thomas Edison :biggrin::biggrin::biggrin:
Click to expand...

OMG....OMG....Noooo!! It can't possibly be!!!


He's actually posting!!!!!
smiley-vault-misc-105.gif
 
Mike:
Don't know if you are even using glue in this build, but it looks almost exactly like an issue I had a while back using thick CA glue as a sealer.

In my case (I guess because if the high humidity here) thick CA seems to degas differently with each pour.
 
Jim, I'm actually using the smallest Florescent light protectors I can find instead, but very similar properties I'd imagine. I use the protectors as I can always run and grab a few if I run low. They are a little larger in diameter, but that makes them easier to pour.

For the clear coat I've tried several things with success, but my main two are clear lacquer or clear enamel. Just have to be sure that both are fully cured first. I try to avoid CA at all cost as it and I don't get along well.

Neil, that's a very thin piece of dichroic glass that has been heated and bent to conform to the tube. no glue.
 
Last edited:
I cast the same way and I have only seen it when casting stamp blanks. I figured it was close to gelling when I put them under pressure, and started to set when not all the air was out.
 
Russianwolf said:
For the clear coat I've tried several things with success, but my main two are clear lacquer or clear enamel. Just have to be sure that both are fully cured first.
Click to expand...

When you say they are "fully cured" how long did it cure?

The solvent based laquer we use at work takes about 72 hours to fully cure and quit releasing volatile organic compounds.

This looks to me like outgassing from whatever paint you used.
 
underdog said:
Russianwolf said:
For the clear coat I've tried several things with success, but my main two are clear lacquer or clear enamel. Just have to be sure that both are fully cured first.
Click to expand...

When you say they are "fully cured" how long did it cure?

The solvent based laquer we use at work takes about 72 hours to fully cure and quit releasing volatile organic compounds.

This looks to me like outgassing from whatever paint you used.
Click to expand...

That's the thing, these didn't get the clear sealant. So that can't be the issue here.

But the way I'm doing things now is
1 Paint tubes and let dry overnight
2 apply clear sealant and let dry overnight
3 bake for minimum 3 hours at 100-150 degrees (done in one hour segments)
4 let stand for two days minimum

With that process I'm getting good results.

This batch I skipped the clear coat, but everything else is the same.
 
You must log in or register to reply here.
Back
Top Bottom