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Fibre Glass Painting


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#1 malc_west

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Posted 22 March 2017 - 07:25 PM

Hi, I have brought some fibre glass panels for my mini to replace heavy and rusty ones. My question is with my metal work I've been primeing using Bilt Hamber Electrox to keep it sound before top coat, can/should I use this on fibre glass panels?
As always thanks in advance

#2 MacGyver

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Posted 22 March 2017 - 07:31 PM

Sure, you wouldn't want your fiberglass to rust now would you! 😐





On a serious note, you would be better off just going straight to high build primer, the zinc would probably just reduce the adherence of the primer and add weight...


Ben

#3 JakeJakeJake

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Posted 22 March 2017 - 10:26 PM

Is the same as metal without the etch primer.

Key the fibreglass, careful not to go too deep especially on any edges, then normal high build primer and go from there like normal

#4 Daz1968

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Posted 22 March 2017 - 10:51 PM

i would always put a coat of epoxy on first, then high build and top coat.

#5 Baldspeed Racing

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Posted 23 March 2017 - 07:42 AM

I sprayed my mini last year which has got a fibreglass front, bumpers miglia arches and boot lid and my local body shop said etch primer first, then normal primer then top coat. pic for detail

 

32378718712_971e106c58_k.jpg2017-01-26_07-45-03 by Rich Wallace, on Flickr


Edited by Baldspeed Racing, 23 March 2017 - 07:43 AM.


#6 MacGyver

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Posted 23 March 2017 - 12:11 PM

i would always put a coat of epoxy on first, then high build and top coat.

Sorry, meant epoxy...
I'm only a panel beater... 😓

#7 tiger99

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Posted 23 March 2017 - 01:32 PM

You need to use an etch primer that works on GRP. Not all metal primers will work. They have been around for a long time. But first as stated already you need to do some flatting,and be sure that all traces of mould release compound have been removed.Wet flatting and the use of a panel wipe are usually sufficient.

 

Here is one possible source:

 

http://www.hids-dire...CFU2eGwodvwYETA



#8 bluedragon

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Posted 25 March 2017 - 03:24 AM

GRP etch primer? I'm very unfamiliar with that idea. I've never seen a product like that for sale yet in the automotive paint and body stores I've been to (in person or online) and not seen that recommended by makes of GRP parts (at least so far.)

 

If we mean the same thing when using the term "etch primer", we're referring to a primer with a mild acid in it usually used to etch metal. This improves adhesion by providing a fine tooth for topcoats to adhere to, notable on bare metal panels.

 

But I'm unaware of any product that contains an acid that will etch polyester or whatever plastic resin is used as the basis for a GRP panel. At any rate, proper sanding of the gelcoat surface is all that's needed for good adhesion of the primer coat. (being very careful not to sand through or excessively thin down the gelcoat that serves as the smooth surface for the GRP panel.)

 

The fine etching that an acid primer is capable of, is not needed on a properly sanded GRP panel IMHO. And if the etch doesn't work on GRP, the acid will be a detriment, not a boon, to adhesion.



#9 tiger99

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Posted 25 March 2017 - 12:40 PM

Well, the product I referred to is said to be suitable for GRP. 40 years ago, no-one was using etch on steel, and paint jobs often had a short life. But in all the books about GRP that I had, it was stated that you need an etch primer. It was even mentioned in the comics of the day, CCC and Hot Car. The GRP resins and in particular the gel coat have not changed.

 

But a mechanical etch is equally good. It should be done with a suitable abrasive, preferably by blasting. You want the surface roughened by maybe 0.01mm,and it needs jagged particles, not beads. Hand flatting is hit and miss. i used it once on a set of wings for a kit car, and they peeled. I was unable to find the correct etch at the time, however hot rod suppliers, with whom I prefer not to deal, and thankfully are mostly defunct, could supposedly supply it.






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