Fabricating Fiberglass Parts

[Jay Beery]

The former owner of my C22 made oversize wood cockpit "glove boxes" for both sides of the cockpit. They obviously rotted out and the boat takes on rainwater. I made a mold for a fiberglass replacement, but no matter how much I wax, I cannot remove the new part without ripping it to pieces. My next hope was to cover the mold with parafin and heat the whole mess to remove the new part. Has anyone been forced to make his own fiberglass parts???

 

[Chris Burti]

Mold Release

As I recall, catalizing polyester resin gives off heat. Mold release wax has a high carnuba content to resist the effect of this heat on release capability. Parafin has a much lower melting point an is unsuitble as a mold release. Meguires used to make the formula we used when I worked for a boat manufacturor 28 years ago. IMHO, I suggest the following:1) make sure your mold is absolutely smooth.2) make sure all surfaces cant slightly to the rear and that there are no recesses to hold the part.3)use a high carnuba content release waxgood luck, FW&SSChris

 

[Greg Stebbins]

In the dark ages.....

We built the part out of thin wood (balsa) or cardboard and then applied the fiberglass mat to the construction. You end up with a good strong part and way fewer manufacturing issues.Greg

 

[A.L. ("Jim") Willis Pres of ISLAND GIRL PROD.]

Releasing agent

Wacker Silicones (Adrian Michigan) make mould releasing agents. They contain Silicone resins which actually cure in response to heat. Wax alone is not a good releasing agent as it is not "Slippery" enough.You can probably buy properly formulated mould release agent from TAP Plastics who also sell fiberglass and epoxy or polyester resins . Call 925 829 4881 and ask for Conrad Hopkins, their tech expert. I am sure that they would also do mail order.Jim WillisPres IGPIronicall

 

[Andre Cornelis]

Mold release agents

To make mold release easier observe the following:- make sure your mold has a little bit of flare in it- round off all corners- fillet the corners- if you use epoxy to make the mold or the fillets post cure the mold, 24 hours in a carton box with a 100 watt lightbulb- use a hard paste wax, at least 5 coats, buffed in between coats- spray several light coats of hair spray in the mold right before layup