Primer or Epoxy barrier coat?

[Mackaroni]

This is may seem like a dumb question, but here goes...

I am currently sanding the paint of my 1988 O'day and have already sanded at least 3-4 layers of blue off and and working on the at least 2 layers of red underneath. (btw....this is not a lot of fun). My intention is to take it down to the gel coat so that I can apply an epoxy barrier coat and then put new ablative on.

However, I have never worked with an epoxy barrier coat and wouldn't recognize it if I saw it. The boat is new to me, and underneath the red layers is two layers of grey. Could this grey be an epoxy barrier coat that is already on the boat, or is it more than likely just a primer base? I would hate to start standing off an already existing epoxy barrier coat just to turn around and reapply the same thing.

[Boatyarddog]

Barrier coat is grayish in color, if you sand and find that it is under all of the other paint it is likely a barrier coat.
If you sand deeper and find a white layer it's likely your gel coat.
Gel coats are removed completely before applying a barrier coat.
If you sand thru to bare glass just touch up the Bare spots, before applying epoxy, or I prefer vinyl ester for barrier coat.


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[Terra Nova]

Originally Posted by Boatyarddog

...Gel coats are removed completely before applying a barrier coat...

Whoa! Don't you believe this.

[Windcaller]

No you don't have to remove a gelcoat.. if your barrier paint is holding on and in decent shape now then the PO at one time has or had the gelcoat dewaxed before they started with barrier coat. I have sanded a few boats down through the copper coat and layers of barrier coat to the gel coat.

Really depends on how bad the barrier coat is .. dont need to grind if all off you find it in good shape...One thing for sure don't grind down into to much of the gel coat. You really want to leave that .. when you see the gelcoat coming through ease up on the sanding and move onto the stuff you want to remove..If the boat is new to you and or you have never done the barrier coat before.. best you remove all or most of it so when you'r done you know the real condition of your boat hull paint

Gelcoat is your friend if its still in good shape under your layers of agony that you'r removing.

I myself use interlux 2000e 2 part epoxy.. has never done me wrong.. its not difficult to use.. you mix it up per the instructions let it sit a bit then you have like 10 hours to to use it all up.. one thing for sure is that you must keep the lid sealed when not using it and make sure you change your 3/8 nap roller every 10 linear feet.. if you do you will have a great finish.. otherwise you start getting egg shell texture. Dont be scared, after one coat you will feel very confident about doing it.. Also don't over roll a area more than needed to cover it completely. I start at the bottom of the hull and roll upwards. but for sure.. to avoid to much egg shell texture use plenty of rollers.. for my 30'ers I use 6 per coat, I take off the rollers and put them in a bucket of solvent to clean later between coats and reuse.. if you let them dry there done... also rolle your (even lint free) rollers on some blue painters tape to make sure you have removed all the lint..

I also in a gallon of interlux put a 1/4 cup of solvent 2333n every half gallon of 2000e makes for a better smoother paint job..

Dont need to go crazy with worry about a little egg shell you still need to do the copper coats and its all under the water line.. important is enough layers of epoxy barrier coat.

Enjoy.. its rough but rewarding



Windcaller

[CS Cruiser]

Interlude 2000e comes in white and Gray, when putting on multiple layers many switch colours as it helps with distinguishing coverage easily.

[gonesail]

the problem with doing a barrier coat is that the 26 year old hull must be dried out .. or you can actually get blisters between the hull and the epoxy.

[Cheechako]

grey: Sounds like you have a commercial barrier coat. Any blisters?

[Windcaller]

For as many years of experience I have had, Barrier Coat properly done and maintained is the reason there would be no blisters... If on the other hand you have blisters or some.. That is when you have to sand off all the barrier coat to the gelcoat and open the blisters up to the fiberglass and let the hull dry out.. otherwise you'r ok.

I think many people don't understand what the barrier coat is for.. I re-barrier coat my two 30 ers every 8 years -10 years...Sand down a coat or two and recoat. Never have I had any blisters to this day. No reason if done well that you need to open the gelcoat over and over.

That is just my experiance I am sure there are other opinions.

Windcaller

[Boatyarddog]

Depending on the problem, gelcoat is peeled off, the hull is allowed to dry out and a Barrier coat of some kind is used to replace the original gelcoat.
To not completely remove it in most cases results in continued problems.
Remove it before applying barrier coat.
That is the correct application.


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[Terra Nova]

You are talking about hull peeling, part of a process for treating badly blistered hulls. Not a preparation for barrier coating.

[Boatyarddog]

Yes, that is correct, after that process you'll ,apply a barrier coat.


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[Boatyarddog]

Originally Posted by Terra Nova

You are talking about hull peeling, part of a process for treating badly blistered hulls. Not a preparation for barrier coating.

Removing gelcoat does not normally involve hull peeling, if you've got a lot of blisters, small little pockets all over, then a peel may be necessary to end the delamination process.
Depends on the hull condition.
Barrier coats replace the gelcoat.


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[Terra Nova]

Barrier coats are applied over the gelcoat.

[Mackaroni]

Thank you for the replies. If this is the case, than maybe I already have a barrier coat on the boat and didn't know it. I just couldn't tell if it was an epoxy barrier coat like the 2000 or just a paint primer of some sort.

I am sanding, sanding, sanding. One guy and a 30 foot boat takes a while

I do not have any blisters. During the survey, there was a slightly elevated area "abaft the keel" where it showed higher moisture content. I just wanted to make sure I had a good barrier coat on before I started putting more ablative on.

If I already have a decent coat on, maybe there is no sense to sand the grey off to the gel coat?

[Boatyarddog]

Originally Posted by Mackaroni

Thank you for the replies. If this is the case, than maybe I already have a barrier coat on the boat and didn't know it. I just couldn't tell if it was an epoxy barrier coat like the 2000 or just a paint primer of some sort.

I am sanding, sanding, sanding. One guy and a 30 foot boat takes a while

I do not have any blisters. During the survey, there was a slightly elevated area "abaft the keel" where it showed higher moisture content. I just wanted to make sure I had a good barrier coat on before I started putting more ablative on.

If I already have a decent coat on, maybe there is no sense to sand the grey off to the gel coat?

Hard to tell if you have a gelcoat if all you see is grey, gelcoats are usually white, if you see any bare fiberglass, be sure to spot coat those areas with a barrier coat of some kind.
Barrier coat is used to seal bare fiberglass, but may be applied over sanded gelcoat as well.
Standard gelcoat is polyester resin with pigment, sprayed into the mold prior to laying up fiberglass in a new build.


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