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I would check your parting powder.
Steve, I just finished my second pattern because my first pattern had the same sand sticking problem. I used enamel, nice smooth and hard. the sand stuck to it like glue! I thought it was the release I used or poor draft angles. I found some old patterns at an antique shop, the pattern finish looked like some type of none glossy dark varnish however I do not know if it was the original finish. I need to do more research. Dale
I assume you have proper draft on the pattern. I find 1.5 deg is ok for petrobond, my foundry wants 2 deg.I sand the surfaces down to 400 grit, making sure they all feel smothe. THe finish I use is just lacquer. With wood patterns ittakes 2 coats and 3 for the end grain. Sanding with 220 after letting it dry well, then go to 400 on the last sanding. I use parting compound from BCS, don't know what's in it. Apply using an old sock. Rub in all over the pattern on a new pattern the first time, then just dust a bit on after that.Hope this helps,maury
Quote from: maury on November 24, 2013, 02:24:28 AMI assume you have proper draft on the pattern. I find 1.5 deg is ok for petrobond, my foundry wants 2 deg.I sand the surfaces down to 400 grit, making sure they all feel smothe. THe finish I use is just lacquer. With wood patterns ittakes 2 coats and 3 for the end grain. Sanding with 220 after letting it dry well, then go to 400 on the last sanding. I use parting compound from BCS, don't know what's in it. Apply using an old sock. Rub in all over the pattern on a new pattern the first time, then just dust a bit on after that.Hope this helps,mauryDaveI put 2 degrees on everything that isnt round.So is the final finish a gloss finish or the 400 grit sanded finish
That's about the finish I have on my patterns....
Once I got the pattern there, the foundry guys painted it again the silver color ( a fact I only just remembered) I seem to remember that this was a special paint...but this was a while ago. I would try contacting them. Nashua Foundry, Nashua NH. Ask for Pete Lyons.