# Using PR to cast burl cutoffs discussion (looking for info and links)



## Treecycle Hardwoods (Feb 17, 2015)

@Final Strut and I were chatting about casing all the burl cutoffs I have (currently 4 55 gallon drums full) I told him that I bought 5 gallons of poly resin to start my endevour along with some pigments. We kept chatting on other topics then he drops a bomb shell on me..... PR shrinks when curing and can pose problems shrinking away from the wood waste. This was last night when all this was brought to my attention. Since then I have been on a mad dash to learn all I can about this (didn't get to sleep til 3 am this morn) did a little more looking today as I had time and there seems to be one guy on the IAP from Australia who uses it regularly to cast wood because he does not have access to allumilite there. He sells his stuff all over and seems to have happy customers. He has also admitted to the shrinkage problems but he doesn't seem to have a whole lot of trouble with it. I found some other info on PR not related to pens or woodworking but rather artists doing casting with it. There seems to be much more info on that side of PR casting. One of the biggest things I have learned the the last day or so is that PR can be cured with heat instead of catalyst! There was one artist that came up with a solution to use and autoclave (had to look it up too!) which is a pressurized heating oven. Doing his casting with PR this way he was able to avoid shrinkage and distortion. In addition to that I learned that casting PR with less catalyst, pressurization, and then a short low temp bake (like CJ) will help also. I am looking for more information on this topic if anybody has a link i can read or knows of a thread on another forum please let me know. I'm sure there is something we can all learn from this. PR is cheaper than allumilite and has a much longer time to work with than allumilite. If we can figure this out it would be awesome!


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## Final Strut (Feb 17, 2015)

After we talked last night I thought of one pour that I did where there was not a shrinkage problem which then became a problem because I couldn't get my blanks out of the mold. That pour I was doing was a tube in casting and I heated the mold and tube as well as I heated the resin slightly. I had actually upped the amount of catalyst because it was cold. I cast it under 60-70# pressure like I always do. When I took it out of the tank the resin was slightly tacky so I put it in my toaster oven at 150 degrees for about an hour. The resin cured fine but like I said I could not get the blank out of the mold but that was more of a mold design issue than anything. I will show you the mold Saturday which will make the de-molding problem all very clear. I have not tried to replicate the process with waste wood yet mainly due to time and shop temps but it is on my short bucket list.

Reactions: Informative 1


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## Treecycle Hardwoods (Feb 17, 2015)

The guy I referenced earlier said in one of his posts to remove the tacky pour from the mold then bake it to avoid that problem. He mentioned that as long as it is still not a liquid that method is ok. He elaborated by saying that sometimes when he does that the pour is tacky and flexible. He even mentioned to one guy on the IAP that he could cast wood waste then stabilize the whole thing and bake it afterwards to cure the juice. The one thing he had said about baking it is that it gets much harder and if it is baked to hot and to quick it would be brittle. He likened that to using to much catalyst making the pour brittle. The temp he suggested is 150ish give or take a little (he gave the temp as a range of 60-70 degrees C)


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## jetcn1 (Feb 18, 2015)

I will not use PR for casting burl caps as I had lots of them fly apart on the lathe. If you start heat curing it you risk it getting brittle and being very hard to turn . Good luck , there are better resins out there for burl casting .


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