Hi guys i have a slight problem whereby after pulling parts from the mold the mold will have some small indentations from the part, any idea what could be causing this. after polishing the mold i get the same problem after every pull. I’m wet lay uping and bagging the mold, could this be the issue. any help will be greatly appreciated.
mold is made from polyester gelcoat but for the part i’m using epoxy.
thanks
I had the same problem when I put directly the mold in the oven after infusion…too high temperature of oven i think. The same problem using spray glue on the mold surface. I don’t know if it can be your problem
hi i dont cure the parts in an oven, i just demolded then i have this problem, i’m wondering if i will have the same problem once i attempts a proper infusion.
What is the peak exotherm of the resin in the laminate stack when it cures? Sounds like it may be getting too hot.
Possibly a heat issue. Was the mold made with Polyester “TOOLING” Gel Coat?
Is the defect in the mould, or in the part?
mold is made from polyester gelcoat
hi Herman the defect is on the mold after demolding, i’m even thinking of making a new mold but this will take time 
which i don’t seem to have.
In that case the Tg of the mould is not high enough. The curing of the part distorted the mould.
For tool building, always verify the Tg of the material. Normal polyester has a Tg of 50-60 degrees C, which is too low for mould making. The tooling gelcoat I sell has a Tg of 135 degrees C…
Also the mould laminate should be able to survive at these temperatures.
Quick fix for now is to grind out the spot, fill with tooling gelcoat, sand and polish.
Or design the part such that the temperature rise is not present anymore, or switch to another resin with less heat during cure.
thanks Herman, i will have to check on the Tg of the tooling gelcoat i’m using. how do a make sure i design the part such that the temp rise is not present anymore?
Thinner laminate, higher Vf, less insulation materials (foam)