Clear Casting Issue

[Dr Robert]

I use a variety of resin materials, notably alumilite, liquid diamonds and Selmar. Recently I’ve noticed a shiny reaction of the Selmar around a few of my watch parts, particularly where the CA attaches the fixture. I try and be careful and not overdo the CA but sometimes I’ll get some excess which is unavoidable. It almost looks like a shiny crystalline glaze. This is most noticeable on a dark background, black or brown. It shows when bright light hits the blank. Any suggestions??


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[Terredax]

I'm guessing it's where the Silmar isn't bonding and creates an air pocket.
Polyester can be fussy on what it bonds to. An epoxy or urethane would bond better, with epoxy being choice, since the urethane requires pressure.

[Dr Robert]

Originally Posted by Terredax

I'm guessing it's where the Silmar isn't bonding and creates an air pocket.

Polyester can be fussy on what it bonds to. An epoxy or urethane would bond better, with epoxy being choice, since the urethane requires pressure.

Thank you for the reply! It is frustrating to spend a lot of time on the blank design only to have it botched with the resin!


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[Kenny Durrant]

I'll try to offer a suggestion without opening another can of worms. It's been discussed here and with several opinions the CA might be outgassing. I think it does so I'll wait 3 days after gluing to cast. I'm not sure if this pertains to you but might be worth thinking about. Also is it noticeable after it's turned? I've seen with several different blanks when something glossy is used under the resin it's noticeable after casting. When turned it's not noticeable be cause it's right below the surface. I guess you need to decide if it's separation or a reflection. Good Luck.

[its_virgil]

I have often put a coat of CA over labels or snake skin with no ill effects. But I do wait a couple of days to allow the glue to completely cure and outgas.

As much work that is required to get blanks ready yo cady another day or two wait before casting is not much. Your watch parts blanks even more so than my snake skins. Patience is worth having for clear casting.
Do a good turn daily!
Don

[Dr Robert]

Thanx guys for your input. These blanks were left sitting for 4-5 days so the degassing issue should have been taken care of. The “crystalline” effect started to occur and become more pronounced as the polymerization progressed. As careful as I am to adhere small fixtures to the blank, I inevitably get a little excess CA on the border of the fixture and blank. I’m wondering if the Polyester chemically mixed with this or it ran under the CA...tough one. I really like the clarity of the PR but it’s much more of a challenge than Liquid Diamonds or Alumilite.
OK..... One more issue... I started making Cigar pens. I turn the wood shy of the bushings....go thru the usual sanding and finishing to get as smooth a surface as possible. I applied the Cigar Label to the blank using Loctite’s adhesive spray, sealing the edges and wrapped with small rubber bands to insure good adaptation. Three days later I tried clear casting with Barry Gross’s PR...using 6 drops per ounce. I left in the pot for 24 hrs.....when I took it out, the resin lifted the labels in spots.....what do you guys use to adhere this type of label to a wooden blank?? Dr Bob is going crazy!!! LOL


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[Kenny Durrant]

I've found that PR will dissolve the spray adhesive or at least the 3M Brand. I use Clear Elmers.

[Dr Robert]

I’m not familiar with Clear Elmer’s...Is this in the white plastic squeeze bottle which comes out white and dries clear? How long does it take to setup? Do you wrap or bind your label, etc until the Elmer’s sets??


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[Kenny Durrant]

It's in the same type plastic bottle the other comes in but the plastic and the glue is crystal clear. I used the white glue for a long time but it doesn't dry clear so on dark back grounds it would leave a light grey haze. The clear does not. I'll wrap the label to make sure it will stay flat against the tube then apply another coat to seal everything up. I've purchased it at Home Depot and Walmart.

[jttheclockman]

Your problem is air. being trapped under labels watch parts or other cast on parts and not enough time to release with PR or alumilite resins even under pressure. Seal all parts before casting. I like to use Silmar and I heat the resin before I add catalyst to make as thin as possible. Can not speak for alumilite because I do not use it. I have now gone to Liquid Diamonds and to me this is the answer for casting things like watch parts because it sticks to everything and does not shrink and is very thin so gets in all nooks and crannies. Polishes just like PR and is as hard when cured. It gets my two thumbs up.