Barrier Coating

[shamrock]

Hi, Quick question about barrier coating.

My bottom is down to bare laminate. Any imperfections have been coated with epoxy, filled and faired and the laminate is smooth.

My plan now is to roll on 2 coats of unthickened West Systems 105 with fast hardener, then spray an several coats of Interprotect 2000e, then roll on Coppercoat antifouling.

since these are all epoxy coatings, I would like to apply all coats wet on tacky or within the bond window to get the best adhesion and avoid having to sand in between coats.

Will I have a problem applying this way?

The Interlux manual says to let neat epoxy fully cure, wash and sand before applying the interprotect. why would this be necessary or better than a chemical bond between all coats if no fairing is required?

Thanks!

[minaret]

Originally Posted by shamrock

Hi, Quick question about barrier coating.

My bottom is down to bare laminate. Any imperfections have been coated with epoxy, filled and faired and the laminate is smooth.

My plan now is to roll on 2 coats of unthickened West Systems 105 with fast hardener, then spray an several coats of Interprotect 2000e, then roll on Coppercoat antifouling.

since these are all epoxy coatings, I would like to apply all coats wet on tacky or within the bond window to get the best adhesion and avoid having to sand in between coats.

Will I have a problem applying this way?

The Interlux manual says to let neat epoxy fully cure, wash and sand before applying the interprotect. why would this be necessary or better than a chemical bond between all coats if no fairing is required?

Thanks!

You will have trouble if you attempt this. A few points-


It is almost impossible to apply WEST epoxy (or any other) in an acceptable finish.


Your bare glass will be extremely porous. Much too porous for 2000, which is quite thin. Hence the need for resin. You need to work this resin into all the pinholes which will appear when you start coating, to fill them. One coat generally will not do this, hence the need for two (or more).


Sanding and solvent wiping your epoxy after cure will provide an acceptable finish and fill pinholes, while also removing any amine blush.



People always try to skip steps on this. It's why so many bottom jobs get redone. Don't be that guy.

[Nicholson58]

We stripped our bottom, blasted & filled, ground, faired etc. We rolled on 6 coats of Interprotect. The Petit and Interlox reps were at the yard when we were about to start. They worked with me towards the best bottom for our mixed fresh/salt plan. Instructions were to apply the Interprotect quickly, despite the instructions on the can. Each layer was to follow the next as soon as the previous layer was dry to touch. That amounted to about a 45 minute delay between coats. For us, each coat was 3-4 gallons (58 feet). The Petit guy had us apply the VIVID by the same plan as soon as the Interprotect was dry to touch. We applied 10 total coats in three days and then let it set for a couple weeks min. If you do this, it is important you do not launch for an extended time or the solvents will not have time to escape. The longest these guys recommended between coats was 12 to 18 hours to avoid sanding. If you use VIVID, be sure to thin it and apply in thin coats.

[Terra Nova]

Originally Posted by minaret

...It is almost impossible to apply WEST epoxy (or any other) in an acceptable finish...

This.

You'll want to fair it after applying the WEST epoxy.

I would add that, particularly in warm weather, you should avoid the use of fast hardener. And especially on a project like this where you want extended pot life and longer re-coat times to maximize absorption, so you can go over and over the same surface as the resin soaks in and air escapes. Better to take your time rolling and not introduce air into the mix.

[wingless]

Apply the epoxy per the instructions.

The Interprotect 2000e instructions should be followed exactly.

The Petit Protect instructions are an okay guideline, but talk to their technical support prior to application to obtain the secret instructions required to prevent blisters within the barrier coat.