Hi Blair

This might be a little late but, as I used to be involved in the manufacture of this product, the quick and easy fix is to up the amount of thinners - BUT, you might need another coat to retain the desired thickness.

The condition I know of as Milking or Blooming - it is trapped humidity. This is why "wet-back" spray booths are a really bad idea - great for solvent filtration, but troublesome for the finish.

You really should control your humidity to around 60%RH - too low causes ESD issues. A de-humidifier won't cost much and makes life easier. Moisture traps in the air line are essential.

You might like to download a copy of our Facts & Data Book on Conformal Coating from:

http://www.gen3systems.com/techshot-Conformal_Coating.php

I hope this helps

Graham Naisbitt
Gen3 Systems 

On 29 Aug 2012, at 15:03, Blair Hogg wrote:

> I'm hoping that Technetters can share some light on an issue that we occasionally experience here - we coat some of our boards with 1B73 conformal coating, for some we have a spary machine, others a sprayed by hand. 
> 
> Every so often we will process some board through coating and they will have a cloudy / milky appearance in the coating. We have been told previously that this happens when humidity is up, since our manual spray coating area is not in an air-conditioned environment. 
> 
> Anyone else ever have this problem? How did you fix it? 
> 
> Thanks,
> 
> Blair


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