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Coating System for Glass Fibre Composite Phenolic Resin Moulded Component.

I would like to know the best coating system for Glass Fibre Composite Phenolic Resin Moulded products. Currently I am using a Polyurethane Primer followed by Polyurethane finish coat, which is exhibiting poor adhesion with the substrate as also poor impact resistance. I would appreciate suggestion alternative coating system, where the final top coat should be aliphatic polyurethane.

Manoj Saraf
- Multicoat Systems, Calcutt, West Bengal, India


Pardon my query, but are you sure that there are no release agents or waxes on your parts?

On the face of it, it looks like you have an adhesion problem for some reason or another and if those parts are clean, dry, lacking any release agents, then you Pu should stick ... further, you mention that you have a poor impact resistance. Are you using the McCoy, the true 2 component Urethane or some so-called Urethane paint having perhaps, if you are lucky, only l0% or so of Pu in it, i.e., a regular Pu paint?

The other thing is that your parts may be totally perfect and have a super smooth finish. Ow! Paints etc will always adhere better to rougher finishes as the surface area increases.

Anyhow food for thought! Cheers !

freeman newton portrait
Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).


After producing a Glass/Phenolic component we coat with a thin layer of epoxy resin prior to painting. Usually one of the two component epoxy resins let down with a solvent.

Ciaron Murphy
- Great Britain


Polyurethane systems should be compatible with your substrate. I suspect that your problem is surface preparation. Make sure you are giving the part a good rubdown with a coarse grit sandpaper. If you still have problems, a vinyl ester (modified epoxy) primer would be a good option. something like Derakane 8084 from Dow would be ideal. But whatever you use, surface prep is the key.

Good luck,

Kevin Curran
- Melbourne, Victoria, Australia

I was interested in Coating System for Glass Fibre composite Phenolic resin moulded component. I'm currently using a 2pk aliphatic polyurethane lacquer , it has excellent gloss & u.v. protection however it leaves the surface a little yellowish. also if I use a not so good polyurethane product it does not leave the surface yellow however the gloss is compromised.what is wrong? please help

Karan Lal
buyer - Delhi, U.P., India
February 23, 2011

If the cost would allow I would apply a top coat of 2 pack acrylic/polyurethane clear coat over the lower gloss finish.

Terry Hickling
Birmingham, United Kingdom
February 24, 2011

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