Is this for the Welman? I recommend the following-
Wax your masters well, I find half a dozen coats is usually enough, but not less than that.. Do not be tempted to use silicone wax, it will ruin your mouldings.
Get a cheap can of hairspray from Poundland. Spray the masters with this and let dry, apply a second coat. I find this works more consistently than PVA, which has a tendency to separate unless you apply very thin coats. Hairspray doesn't so this, but like PVA it is water soluble.
Apply two to three coats of gelcoat, when dry, but still tacky apply a layer of glass tissue, and chopped strand matt (CSM). I stick with 300 gram CSM, which is pliable, and just add more layers to get the required laminate thickness. A layer of tissue will help to smooth off the roughness of the CSM before filling with polyester putty.
Make sure you get you catalyst quantity right- I use a plastic pipette, and work in a well ventilated space- polyester resin don't half pong. I prefer to laminate in spring or summer, as the warmer weather helps the resin kick nicely.
Don't rule out epoxy resin. Although more expensive, it keeps longer on the shelf, is very low in odour, and gives you a much longer working time. Only use glass fabrics with epoxy or powder bound CSM. Styrene bound CSM is only for polyester.
Another, even simpler solution, is to use polyurethane resin. A company called Smooth-on produce a product called 'Shellshock'. This is a polyurethane resin thick enough to brush on, like gelcoat. This resin is tough enough to not require reinforcement providing you make it about 2-3mm thick (e.g. Engel's new 212 kit is cast from PU resin). You apply two or three coats over your waxed and hairsprayed masters. Sand smooth, and pop off. Simples, and you can demould within an hour or two.
http://www.smooth-on.com/a30/Shell-Shock%3D-Self-Thickening-Brushable-Plastic/article_info.html
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Topic: Where to get some fg supplies and a little advice (Read 4941 times)