blush when epoxy fill coating

Is blush waterproof? I have done alot of laminating, but only applied 1 coat of epoxy to wet out the fabric. I intend to overcoat with another 2-3 layers of neat epoxy to waterproof the laminating as it is in bilge area in places.

Question is, do I need to apply all fill coats timely, or can I wait? I am using west systems epoxy which blushes, but the blush looks waterproof. If I apply peel ply, it seems to absorb all the fill coat resin.


Thanks gt

 

Blush is a waxy like material, it peels off with your fingernail.
It will have no waterproofing ability on top of epoxy. Think about the fact that you can remove it by washing with plain water.

Do the work timely until you get a smooth surface, cause if you don't and you can't get it all sanded off, you will have yellowish dots over lots of the boat after you put on the next fill coat. Of course you can wash with a brush (not too stiff), but that is a lot of work and you won't know if you got it all until you over coat and see the yellow dots. Kind of looks like pus in your boat. Then it is too late until you sand the glass off practically down to the wood.

Next question, if you sand a lot of the glass off - did you get all the blush? Now you get to over coat again and find out. End result - you just took off the expensive glass and epoxy it took you so long to put on.

Just do it right to start. Trust a man who has wasted lots of time and money. Additionally, the wood never really looks as good as the first time when you started. Now you might just decide to paint after all the effort.

 

I've always used a little soap and lots of water to remove amine blush. Never sand until you're satisfied all the blush is removed. Sanding blush will simply drive it into the resin making matters much worse. You will want to apply subsequent coats of resin within no longer than 24 to 36 hours in order to obtain a good chemical bond. If you wait too long you will only get a mechanical bond as the undercoat of resin will have fully cured.

It may be near impossible depending on where you live but I always try to do coating when the humidity is low. If it "feels" muggy you have a good chance of developing blush, especially in the evening as ambient air temperature drops.

Remember, blush is a wax like substance and it will inhibit any additional coats of resin/paint from adhering.

 

no reason why anyone should use blushing marine epoxies when plenty of non blushing epoxies on the market.

 

Thats what I wanted to say... Use a non blushing epoxy. The Gougeon Brothers (West) have done a great job documenting epoxy for the marine environment. However, their epoxy systems unfortunately never were adapted to the ease of use of other systems (although they have had to reformulate for REACH).

If you encounter blush, a good scrub with scotchbrite and a mixture of water and ammonia solves this.

 

Amine blush is water soluble and easily washed off. If you use a ScotchBrite pad while washing the blush off, you can kill two birds with the same stone.