small part help

I have been at this awhile and had a problem with a hatch lid,, it is 20" x 36 here is what I did.. using a well waxed peice of aluminum and some pine boards for edging I made a mold and waxed and clayed in some fillets,, sprayed it with Gell coat, catalyzed at 2% let it cure, Them I skined it with " 1 1/2 oz csm. let it cure and laid in a 12oz fabric and when it cured Polyester resin catalyzied at 1.5% i had a bit of distortion in the flat surface that being aluminum,,, what did I do wrong? and can I salvage the part buy placing in the 1/2" foam and more glass under a vacuum or with weights,, Thanks in advance for the help

 

Don't let the individual layers of glass cure before applying the next one, in a laminate that thin apply all of them at once. And if it's hot out you can reduce the catalyst to about 1% on most resins.

It's normal to have some distortion or warp in an FRP panel with no core, the lip around the edge will help it to hold its shape, but depending on the height of the lip it may not be totally flat.

You can clamp it down or put some weight on it and glass on a core, let it cure well before removing the clamps or weights.

For a flat mold surface I like to use old window or sliding door glass, it's flat and stays that way, and most of the time it's free.

 

Thanks,, I think with your help I may be able to save the part,, I had no problem or effort in releasing it form the Aluminum,, but I will hunt up some glass as well !