Bubbles with fabric and PR

[alankulwicki7]

I'm trying to cast a piece of fabric and it never seems to come out. Here's a picture of my latest attempt.

What I did this time was glue the fabric to the tube with CA and waited about a week to cast it. When I went to cast it yesterday, I smeared the tube with resin, placed it in the mold and then slowly poured the resin in. It was then placed in my pressure pot at about 35psi. When I checked it 8 hours later, there was one small spot with bubble. This morning I checked and it looked like this.

What am I doing wrong?

 

[Ed McDonnell]

Hi Doug - I'm going to offer a suggestion for an alternative process rather than thoughts on what went wrong for you.

What you are trying to do is not much different than making a fiberglass layup. Except you are using fabric instead of glass cloth. The process should work pretty much the same though. I would suggest forgetting the CA and instead use PR to apply the cloth to the tube.

Mount your tube between bushings (acetal would be best, but waxed metal will work, mandrel or TBC doesn't matter). Saturate your piece of fabric with PR resin and then wrap it around the tube, using a roller (or your fingers (in gloves) to work it out smooth. If you can turn your lathe on very slow (no more than 100 RPM) you can power smooth, otherwise turn lathe by hand as you are smoothing.

After it cures, cast it as normal. Using vacuum instead of pressure would be my choice, but if you don't have vacuum, it doesn't much matter what I would choose.

Good Luck. Don't forget the safety gear (mask, googles, gloves) and check out youtube for videos on fiberglass layup.

Ed

 

[Kenny Durrant]

I'm no expert but I'll give you what little information I know. I think what happened to you is that the air in the blank spread after releasing the pressure. There was probably more air in there than just the bubble. What I do, and I still have trouble, is glue the object with white or Elmers glue. If it is porous like fabric or feathers I coat the object with diluted glue to help fill the voids and seal the material. Like I said I still have trouble but this seems to help a great deal. Good Luck.