PR bubbles

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DFerguson777

DFerguson777

Member
Joined
Aug 18, 2009
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126
Location
West End, NC
I bought at Resin Saver Mold (which I love!), mixed up my PR colors with Cat (mixing and pouring very slowing and carefully). I'm getting pin hole bubbles that can't be filled with CA. They get filled with white dust. What am I doing something wrong? Do I need to Ultra sonic before I mix? Get a presure pot?

I'm getting cool blanks, but they go to crap with the little bubbles.

-D-
 
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DFerguson777 said:
I bought at Resin Saver Mold (which I love!), mixed up my PR colors with Cat (mixing and pouring very slowing and carefully). I'm getting pin hole bubbles that can't be filled with CA. They get filled with white dust. What am I doing something wrong? Do I need to Ultra sonic before I mix? Get a presure pot?

I'm getting cool blanks, but they go to crap with the little bubbles.

-D-
Click to expand...

Well forget the pressure pot with the resin savers. The mold can't handle the pressure. I guess you are using just colored PR on a painted tube nothing on the tube. I have started using ultra sonic and for me clear cast not too sure how much it helps but I do believe it does.

Now what I believe is happening to you. If you are mixing in dyes or pigments to get color you are introducing air in the PR at that point. You need to get that air out BEFORE you add the MEK and not introduce any more air when you mix in your MEK. I would heat the resin to about 100 put your mixing cup in a container of hot tap water. Add the color before the MEK then I put into ultra sonic to help get rid of air then leave set another 1/2 hr to get all the air out. You have to get all the air out the tiny bubbles you introduced when you added your color. Then carefully and slowly add your 3 drops per once OF PR with it warm it will help let the sir rise to the top.

I think you need to work on trying to keep the air out when mixing hard to do when adding color. That is why you need to let it sit after the color before the MEK.

good luck
 
Are you sure they are bubbles? What tools are you using to turn them? Roughing gouges or spindle gouges can be quite agressive and cause what you describe...but they are not bubbles but chip or tearout. Even though they fill with white dust, a couple of coats of CA as a CA finish on the turned, sanded, and polished blanks may do more help than you think. Re-evaluate the situation and make sure whether the cause is bubbles or tools.
Do a good turn daily!
Don
 
I think you need to go back to basics..
Reading your post, I don't think you're doing anything to help the bubbles in their coming to the surface to pop and get out of the middle..

IMO, mix as normal, just like you're doing, but introduce something to your mold to get rid of the bubbles... I set mine on my scroll saw platform and turn on the scroll saw.
The vibrations help work the bubbles out..
Others use the ultrasonic, some use a drill on the bench to create the vibrations, etc etc

Good luck!
 
Sounds like you are introducing air when you are mixing your colors and/or hardener. What I have been doing is using a vibratory mechanism (that's what I call it) mounted under a pan. The molds sit atop the pan and I don't get that many bubbles in my finished products. One or two so far, but not as much as I thought.

I also have had what Don was describing. I was a little too aggressive and my tool was starting to dull, and all of a sudden I had a whole section of what I thought were air pockets. I sharpened up and used some CA to fill the holes in and never saw them again.

If you are getting white powder in them, try picking the powder out with a toothpick or something and them filling the hole with CA before continuing.
 
I recently finished a (bought) blank from PSI and upon polishing found the bubbles/chip out. They had filled with polish. I cleaned them out with a dental tool, dabbed them each with thin CA and gave it a coat of med CA on the lathe. "wet" MM again and polished then waxed. Good as new. Good luck.
 
You say they are pin holes so I doubt chip out is the problem . Heat your resin when you mix your pigment in and let it sit for about a half hour or so to allow the bubbles to rise to the top , give your mixing cup a bang on the table after about 15 minutes to break loose any bubbles on the sides and bottom . Then very gently mix in your MEKP so you don't introduce any new bubbles . When you pour it into the mold , pour it in a thin stream in one corner of your mold to avoid any bubbles from pouring .
 
I read somewhere that it helps to pout through a fine screen of some kind. I don't know if it helps or not, I have never done any casting, not yet anyway.
 
PaulDoug said:
I read somewhere that it helps to pout through a fine screen of some kind. I don't know if it helps or not, I have never done any casting, not yet anyway.
Click to expand...

I don't know about that. I sure wouldn't do that sounds like your just asking for trouble. Why would you want to run a liquid through a screen unless your trying to get out lumpy pigments and if that is the case you got bigger problems. Like every one said back to basics heat your resin a bit carefully slowly mix in your color let the resin set a 1/2 - 1 hour keeping it warm. Then you feel all the air is gone very slowly stir in your MEK. Put your 3 drops per once in and with your stir stick slowly put it in the resin and mix do not move your stick up and down just slowly stir. It doesn't take much for the MEK like it would the color. Then slowly pore in one corner of the mold and let the resin flow through out the mold. Then let it set you should be just about bubble free and any bubbles should rise.

Let us know how you are making out.

.
 
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