ady8077
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| posted on 5/12/07 at 05:38 PM |
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Fibreglass probs
Hi all
I've made a buck to make moulds off, to get a good finish on the buck i painted it with high build primer, sanded back and gave it a top coat of
gloss black car paint
tried making my first mould yesterday, went to seperate tonight and the resin seems to have melted the paint? had a right job seperating them, any
ideas what i've done wrong?
Adrian
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blakep82
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| posted on 5/12/07 at 05:40 PM |
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i'm not sure you should paint it. i think there's some kind of release wax you put in there instead
________________________
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robertst
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| posted on 5/12/07 at 05:44 PM |
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have read you do have to paint it, but give it a lot of waxing before moulding. gel coat must also be thoroughly applied. sounds like maybe you
didn't wax it enough?
funny i'm JUST about to start moulding myself, so it'd be interesting to find out what went wrong with yours.
Edit: oh i have just read you made the mould yeaterday and separated it today?. aren't you supposed to wait until fully cured, which is like a
week? one day seems too short to me no matter how small the piece u made..
[Edited on 5/12/07 by robertst]
Tom
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emsfactory
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| posted on 5/12/07 at 05:46 PM |
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Did you use celulose paint?
If so that is a no go with normal resin.
You have to use 2 pack.
I have seen celulose used with epoxy resin though. It's more inert apparently.
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dave1888
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| posted on 5/12/07 at 05:46 PM |
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Did you use a release ageng before you applied the gel coat.
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ady8077
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| posted on 5/12/07 at 05:52 PM |
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That was quick 
Used a pva release agent, athough it did dry a little steaky, paint was halford own brand, could it be celly?
Adrian
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Volvorsport
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| posted on 5/12/07 at 05:57 PM |
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itll be cellulose if its melted the paint , sometimes aerosol 2 pack can be bought , that seems to melt aswel , ask me how i know .
www.dbsmotorsport.co.uk
getting dirty under a bus
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emsfactory
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| posted on 5/12/07 at 05:57 PM |
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Yep, wrong paint.
I have found that in general a two part paint or varnish will be fine with fiberglass resin.
Spray can stuff just melts. I did it once too and it looked very,, scrotumy.
Was gutted. You only do that once though so the hard bit is by at least.
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twybrow
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| posted on 5/12/07 at 06:55 PM |
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I've been making a mould for a dash board at work. the mould is built using MDF/, radiused (19+mm) with body filler (which is generally
polyester based). Onto this i built up a good layer of exactly the same paint as you have mentioned - Halfrauds Hi-build primer and a regular can of
grey primer.
The hi-build is used to fill any surface pores. This is then sanded back (wet n dry), cleaned with soapy water and a layer of normal grey primer
applied. It is important to test the paint with your resin first. As said, epoxy tends to be less agressive, whereas the styrene in polyester will
cause the paint to dissolve.
I applied two good coats of wax, then an additional 5 coats of as PTFE release spray. I had no issue with the resin dissolving the paint. I will post
some pics soon as I may have a few spare dash blanks!
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smart51
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| posted on 5/12/07 at 07:12 PM |
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the styrene solvent in polyester resin disolves all sorts of other things, including paint and polystyrene foam. Wax coats will not stop it.
If you can separate your buck out of the mould, you will have to refinish it with something other than paint. Sorry.
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ady8077
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| posted on 5/12/07 at 07:32 PM |
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Thanks for the replies
got mould and buck apart, bucks ok, but need coating in something to cover the filler etc.
Any recomendations on a more durable paint / varnish?
Adrian
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big_wasa
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| posted on 5/12/07 at 07:36 PM |
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was going to have ago myself soon.
Would enamel be any good ?
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Volvorsport
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| posted on 5/12/07 at 07:46 PM |
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nope .
polyurethane varnish , 2 pack paint or polyester reface can be used .
if its a rough mold , pva , spray wax coating etc .
www.dbsmotorsport.co.uk
getting dirty under a bus
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stevebubs
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| posted on 5/12/07 at 07:54 PM |
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quote:
Originally posted by ady8077
That was quick
Used a pva release agent, athough it did dry a little steaky, paint was halford own brand, could it be celly?
Adrian
Halfords paint doesn't work well with PVA release agent.
Works fine with a good 10 layers of Wax, though
In this weather, you also want to make sure the paint is fully cured. Try leaving it a week between paint and trying to pull the mould.
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Syd Bridge
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| posted on 5/12/07 at 08:31 PM |
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I've said it here a dozen or more times already, but I'll say it again....
PVA has no place in a professional grp workshop, so don't use the stuff.
Plenty of wax is the only answer, and gives a smooth finish, which the pva will not.
Put the wax on--allow to dry--buff with machine preferably--allow to harden(anything up to 2hrs or more in this weather)---apply more wax---- and on
and on.
6-8 coats of wax should work. It is imperative that the wax be allowed to harden between coats, otherwise the new coat just wipes the previous off. As
Volvofella says, 'ask me how I know.'
Plug surface needs to be 2pack at a minimum. I know other cheaper paints can work, but 2 pack and wax never fails. Well, for me anyway.
Cheers,
Syd.
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Triton
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| posted on 5/12/07 at 08:55 PM |
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quote:
Originally posted by Syd Bridge
I've said it here a dozen or more times already, but I'll say it again....
PVA has no place in a professional grp workshop, so don't use the stuff.
Plenty of wax is the only answer, and gives a smooth finish, which the pva will not.
Put the wax on--allow to dry--buff with machine preferably--allow to harden(anything up to 2hrs or more in this weather)---apply more wax---- and on
and on.
6-8 coats of wax should work. It is imperative that the wax be allowed to harden between coats, otherwise the new coat just wipes the previous off. As
Volvofella says, 'ask me how I know.'
Plug surface needs to be 2pack at a minimum. I know other cheaper paints can work, but 2 pack and wax never fails. Well, for me anyway.
Cheers,
Syd.
loadsa wax then loadsa wax oh and plenty bit elbow grease.
Mark
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twybrow
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| posted on 5/12/07 at 10:36 PM |
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Syd how can you say PVA has no place in a GRP shop? Yacht builders use it all the time for textured/slip resistant surfaces on mouldings, as wax
doesn't go on well on highly textured surfaces. Admittedly, this is not, and I agree not the best choice here, but it does have its uses...
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Fred W B
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| posted on 6/12/07 at 06:17 AM |
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surfacing primer
Cheers
Fred W B
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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Syd Bridge
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| posted on 6/12/07 at 09:56 AM |
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quote:
Originally posted by twybrow
Syd how can you say PVA has no place in a GRP shop? Yacht builders use it all the time for textured/slip resistant surfaces on mouldings, ...
Not 'round here they don't!
I've got yacht builders, people who make parts for planes, and even for Aston Martins, all within a couple of miles of me, and you won't
find PVA in any of the workshops.
If you have got to entertain PVA, you're doing something wrong. If wax doesn't work satisfactorily, then one of the many liquid surface
coatings will most certainly do the job.
And my old grandad wouldn't have the stuff near him. He built more than a few waterborne things in his life.
Do the job properly, first time.
Cheers,
Syd.
[Edited on 6/12/07 by Syd Bridge]
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twybrow
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| posted on 6/12/07 at 10:14 AM |
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We make major structural parts for aeroplanes, and we have PVA in our shop...!
It doesn't tend to get used on the carbon/epoxy work we do (certainly not in production) , but it has its uses in other areas of composite
manufacture.
One could argue that your use and campaign for use of wax is somewhat primative - why not only promote semi-permanent release systems?! It's
becuase different parts require different slip properties and surface finishes. there is a use for PVA, but obvioulsy not for the work you are doing.
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Syd Bridge
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| posted on 6/12/07 at 02:07 PM |
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Wax, primitive?? That's a bit rich coming from someone promoting pva!!  PVA is horrible stuff.
Geez,in a hurry, I've put shellac directly onto mdf patterns, then wax and moulded straight onto that. You can stick that pva where the sun
don't shine!
I know about and use the modern(? It's been around, in various forms for more than 30years) stuff, but who on here is going to spend £120+/us
gallon for a small project? When he can go down the road and get a tin of original Simoniz hard wax for a few pounds and get the job done just as
well?
I'll say yet again, PVA has no place in grp work which is being done properly! Even half properly.
Cheers,
Syd.
[Edited on 6/12/07 by Syd Bridge]
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ady8077
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| posted on 6/12/07 at 06:38 PM |
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Hi all
Thanks for the advice, any recomendations on the best wax to use?
Also i have another part to make, an airbox, forwhich i have used plaster. I have sanded it to shape and was going to paint it, as 2k paint is abit
dangerious for home use would i be best to varnish it? or will wax be ok on bare plaster?
Thanks Adrian
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Peteff
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| posted on 6/12/07 at 06:45 PM |
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Carnauba wax is the original and you can get it in aerosol. I used block furniture wax polish for the little bit I did and it worked alright.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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