Ofer,
As Joyce said, they are costly for a reason.  But I think you will find 
that 1B31 and 1B73, as solvent based acrylics will be the more economical 
choices for hostile environments.  There are other urethanes or silicones 
that you might consider, but those are not as reworkable as the acrylics. 
Here are some of the "it depends" factors:

How important is rework and repair, or is this a throw away item?  If 
rework is not an issue, urethanes and silicones become more attractive.
Is this class 3 hardware and what are the consequences of failure?
When you say dust, moisture, and pollution, how dusty, how moist, and how 
polluted?  Chemical resistance becomes very important here.
What is the design life of the assembly?
How good is the enclosure around the assemblies you are coating?

I have design engineers ask me all the time if they can eliminate 
conformal coating, generally to take cost out of the unit.  I tell them, 
sure, as long as they are making a hermetic enclosure. They don't like 
that response.  For a hostile environment, you have to protect the 
electronics either with the enclosure or at the assembly level with 
coating.  Period.

Doug Pauls
Rockwell Collins




Ofer Cohen-QM <[log in to unmask]> 
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Hello, technetters,
We are coating commercial products that are exposed to urban atmosphere of 
dust, moist and pollution with Humiseal 1B31 and 1B73. These are expensive 
materials. Are there any other coating materials that can be applied for 
this environment?

Thank you
Ofer Cohen


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