Difference in Class A & Class B Sealants

[Stalldog]

Thought I would post one more response, this one from Flamemaster. I questioned them on thinning Class B, and also about maybe using Xylene instead of Toluene since Xylene is easier to find. Here's their reply:

"You are correct that MEK is not acceptable for thinning. While Xylene will thin the material the resulting solvent blend because of the differences in evaporation rates is subject to the formation of micro bubbles which may appear in the cured material.

Also keep in mind that class B material is a thixotropic formulation and no amount of thinning will make it properly brushable and/ or self-leveling.

For over coating B with A (brushable) the best recommendation is to the class a material which is truly brushable and self-leveling.

Respectfully,

Ken
--
Kenneth F. Chenard
Vice President, Sales
Flamemaster Corp
Nadcap AS9100 ISO9000"

So, my take on this regarding using Xylene to thin Proseal, unless one wants porous Proseal, don't use it.