West System fiberglass repair - What does NOT stick to it?

[maillon]

Hello,<br /><br />I am doing a repair to a small sailboat around the mast step. Any recommendations on what I can use to form the openning yet remove it once it is dry? I'm thinking PVC with grease. Any thoughts would be greatly appreciated.<br /><br />- Mike

 

[Paul Moir]

Re: West System fiberglass repair - What does NOT stick to it?

I just remebered reading this artical. Hair spray and car wax are used as mold release agents (to keep the epoxy from adhearing to a mold). Here it is from the horses mouth.

 

[imported_Paul_H]

Re: West System fiberglass repair - What does NOT stick to it?

I've done a fair bit of glass work. What I prefer to use is first a paste wax, and I like to put on two coats, followed with Poly Vinyl Acetate (PVA) brushed on. In addition to the mold release agents, you need to make sure you have sufficient draft, and smooth surfaces. It is possible to have items that aren't adhered by the glass, but are physically locked in place, hence the need for draft and smooth surfaces. <br /><br />Whatever extra time is needed to plan and execute a good release is well worth the effort, as one stuck piece will permanently give you a bad disposition <br /><br />Plugs for molds can be made from most anything, wood, foam, dry wall mud, bondo, etc, etc. Just make sure the materials are comapable, bondo and poly resins will melt most foams.

 

[BillP]

Re: West System fiberglass repair - What does NOT stick to it?

This can be done with common materials. Make the form (plug)out of cardboard or any other material that will do the job. Where the resin will make contact, cover the plug with wax paper or saran wrap. If you want to get fancy use a sheet of mylar (or transparency sheeting). Tape the whole piece to the deck (place tape below deck I'd guess). Then glass up and peel the plug out. If the mast is perfectly round any disposable picnic cup made of waxed paper or plastic may work for the plug.<br /><br />I've used all types of mold releases and for your application you don't need the "professional" stuff. Besides that, too much mold release wax can actually make parts stick together. A common mistake for novices.