Good afternoon to all,

I am building a female mold that will beused to make a carbon fibre marathon canoe (18’6”). I have good skills working with fibreglass but this is my first experience in making a femalemold.

The mold is based on wooden slats lined with 1” foam and  lined once more with fibreglass. The fibreglass  is then finished with the usual body fillerand mold primer/hi-gloss coats to make it a glass finish. As you may realise,the front and back end of the molds are extremely streamlined and I find itimpossible to sand down to a glass finish.

The alternatives that I have come up withwould be to 1) cut the mold in half and work on each side separately thenreassemble to lay the carbon fibre cloth. The disadvantage might be that Iwould not end up with symmetrical sides. Option 2 would be to lay the carbon fibrein the mold as is but finish the exterior of the canoe’s ends to a glass finishafterwards. Finishing the outside to a glass finish after unmolding seemsdifficult to achieve. Any comment and recommendation would be welcome. 

Manythanks.

Z

I've just finished a plug and a mould for a GSXR Dragbike tank cover, I had the same issues with the High gloss Pattern coat, stripey and rather uneven, even on top of a completely flatted down cover of Pattern Coat primer.
(I can paint 2-K  boat varnish with the type of brush I used, to a level that looks like it is sprayed on ... I've had years of practice on boats ...)

I also had to use 240 grit on a circular sander to speed up my work.. I had to sand so much down that i broke through the high gloss i a few small places, so I decided to try spraying the High Gloss, using the Gel-coat cup gun.. That actually worked MUCH better, the second coat was much smoother  But it still had som areas of "orange peel texture"   I sanded this down using dry 400 grit, then went up to 1500 wet sanding .. I Polished only with coarse compound, since I wanted a satin finish in the plug and mould.  The (Unimould) mould came out very nice, even though I was in a dreadful hurry and did the whole process in less than 24 hours....

I then did a small test, and thinned the High Gloss Pattern Coat with around 8 % Acetone ... then brushed it on ... MUCH better result ...   Might be worth a try, If you can not spray your plug...

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