plug finishing-duratech questions

I've joined into a 30' production sailboat project.The plug is at the point of being satisfactorly faired to 8' ,,80grit,,with a few highspots barely showing (from glass layer below).--------I understand that 'duratech ' primer is an acceptable primer to go right through buffing,,then laying up the mold--anyone familiar with this?
What's the best way to complete a good plug from there?--I'm thinking to spray some red pigment blended with duratech clearcoat(as a base marker) then coat out with a primer/clearcoat blend,,,,sanding through to 400,,then buffing......aren't sure what to use for parting agent.
Thanks for assistance!

 

Seamonkey,

Don't know whether the 80 grit and 400 grit are equivalent to European 80 and 400. But if so, then you better go on untill a 3000 grit gives you a near perfect gloss. Then you start using polishing liquids. 3M have a wonderful system for this.
(600/1000/1500/3000/liquids)

I have worked with Durabuild years ago, wonderful stuff for plugs; probably what they call Duratech now.

Luck,
Lucas

 

lucas,thanks for your reply.......i imagine that our grit's refer to the same #/sq.in-----indeed 400#or 600# is early to buff off and take a print,but the assumption is to continue the process in the mold,where any dips or porosity in the plug will become bumps above the surface and in a way expose themselves......I had thought to go your way on this but the customer's approach seems rather eloquent ,,especially when the season is changing here,,the plug base is somewhat light,,and I have a concern to get a more stable base with a mold before all is lost(not the best start,really!).

When you were using duratech primer for plugs,would you use anything harder in your final coats before the buffing??
It's interesting....I've never seen buffing compound refered to by it's equivalent grit #,,but have always thought it should be!--glad to see they figured that out over there ,in the 'old world'!!

 

Hi Seamonkey, as said what we used was called DuraBuild, but probably the same.
And no, we did not use another finishing than the really, highly polished DuraBuild on the plug. Like a mirror .... Then release wax.

I wouldn't want to try fairing a mould, that's no job ! (may be I understood wrong: "few highspots barely showing ..) It is the plug that must be as near to perfection as possible !!

When you start laminating the mould, take it slow. We think no more than 1kg of glass per session, then letting it cure and shrink for 2 days before the next session. Unfortunately some sanding in between has to be done (we believe) to get extra 'grip'.

If others have a different opinion / experience, let them now speak or for ever keep their silence ...................................................................

Lucas

 

An update,since my first post here......from the initial point as described,a final spray of duratech blended with duratech clearcoat was sprayed to the plug,with sanding of 180,,,320,,,500 grit using progressively smaller sanding boards,,and random orbital for the 500 grit.......'Aquabuff 2000' is now being applied,with gorgeous results.Aquabuff has 2 products --the first takes a 400 or finer surface,,,the second comes in at ~800 grit.
Unfortunately,the plug framing/skin was built a bit light,such that the skin has some light flex to it which causes some print through from the skinlayers and battens,,,so the only manner I can think to rectify any 'patterning' at this point,will be to 'cut in 'to the sturdier mold once made,if there's any visible patterning--sad,but true!
My personal conclusion relug making for 'next time' would be to build a frame as normal,then layon coring,and glass it as I would a 'one-off'...this would both give a solid base to fair on for plug building,and also can become a ready prototype for testing,,,in any case,would seem to be the best way to send the least materials to the dumpster at completion of each stage!

 

........dura-tech.......a final note---Durateck has a vinylesther version,,which I've used extensively in repair work,,and is considered appropriate for underwater osmosis protection.---I had recommended it's use in the finsh spray-layers on the plug as I considered it probably better for micro-porosity....the owner went with standard poly-duratech,blended with dura-tech's 'clearcoat'....well it turns out that this caused a problem in using 'AQUABUFF',a water based compound....in that the finish layer absorbed water from the aquabuff,,and caused the poly based build layers and wood-skins underneath to flex and breath!!!---Obviously,,the plug construction ,with a single layer of veilcloth underneath,was underbuilt,,,and what a headache a little haste,,and economy has caused !!!!!!
Hopefully,this shared experience will save others from similar!!

In the previous message I noted how building a 'one off' would avoid this,,but if you're bent on going straight to a mold from the plug,,definetly take the time/expense to build a reasonably substantial layer of glassing before proceeding!!......and if in a tempermantal climate for moisture/temp,,,it's also worth sealing all wood involved in skinning the plug-frame!.........cheers!!