Redo a barrier coat?

sailingdog · Mar 9, 2010

If you're going to scuff the barrier coat, it might be worth adding another layer to it.

One thing I usually recommend, especially if they are using IP2KE barrier coat is to alternate colors. That way any damage to the outer layer can be readily seen.

If your current barrier coat is grey, get a can of the white barrier coat and put that over it...then hot coat the first layer of bottom paint to the new barrier coat.

When you have to sand the bottom next, you can tell where you've sanded through the barrier coat's outer layer whereever the grey shows up.

Warren Milberg · Mar 9, 2010

My advice is to keep it simple: if your boat is barrier coated and blister free why mess with success? Remove as much of the badly adhered ablative bottom coat as you reasonably can, repaint, and go sailing.

Hermit Scott · Mar 9, 2010

I was wondering about this myself. The recommendation is to barrier coat then hot coat the bottom paint on that. What is the recommendation when bottom paint is needed again? So does barrier coat stick to anything, but bottom paint will only stick to barrier coat well before it cures??
Does the same kind of bottom paint stick to an old layer that has been propely scuffed?

jcastle · Mar 10, 2010

The best application is stated above..... You should remove the bottom paint and get a scuff sand the barrier coat with 80 grit. You should then apply another coat of Epoxy Barrier Coat Primer. You MUST hot coat the epoxy with bottom paint. This is called hitting the "window". If you do not then you WILL have poor adhesion between the epoxy and the bottom paint. Hot coating is done by simply applying the epoxy and the first coat of bottom paint in the same day. I have had great success with Tuff Stuff Epoxy Primer. It is the Sea Hawk version of interprotect. It too is gray, but a little darker than the interprotect. It is also a higher build containing more solids, meaning that you can put on less coats to equal that same amount of primer.

If you want a cheaper route, you can just sand off the bottom paint and put back bottom paint over the old barrier coat. It will stick if it is scuffed with 80 first. You just have no way of knowing how much is on there. So I would freshen up the barrier coat with 1 new coat and then 2 coats of bottom paint. I have listed some links in this post of the products that I have used and have found are the very best.

Epoxy Primer: Tuff Stuff Barrier Coat Primer
Bottom Paint: Biocop TF

Here is also a link on how to apply a barrier coat system.

Maine Sail · Mar 10, 2010

BobM said:
I know they recommend hot coating, but it seems ridiculous to me. Why would you do anthing to chemically impact the cross linking and setting of the epoxy?

Because it does not negatively impact the crosslinking and is what has been tested and proven to offer the best adhesion by the manufacturer. You can not however use a water based paint like hydrocoat hot coating.

The hot coat open time for epoxy to epoxy with IP2KE is weeks but only minutes to hours for paint to epoxy depending upon temp...

Sumner · Mar 10, 2010

jcastle said:
The best application is stated above...............Bottom Paint: Biocop TF..............Here is also a link on how to apply a barrier coat system.

Quick question, have you ever used the Cukote Biocide Plus Self-Polishing Bottom Paint?

http://www.bottompaintstore.com/Cukote-Biocide-Plus-Self-Polishing-Bottom-Paint-GL-3500-GL.htm

I'm wondering how it compares to the Biocop TF you mentioned.

We got the Tuff Stuff and Cukote Biocide Plus recently and I'll be putting them on our boat latter in the summer before we head to Florida in the fall. In the future we will of course have to add more bottom paint and I'm interested in the comparison between the two in case we wanted to change.

Thanks,

Sum

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jcastle · Mar 10, 2010

I have a friend that uses and it works really well. It is probably the best paint out there besides the Biocop tf.
Cukote Biocide uses irgarol as the additional biocide and slime fighter, where as Biocop TF uses zinc omadine as the slime fighter.(just a little better performance)

Either way you can't go wrong...

Sumner · Mar 10, 2010

jcastle said:
I have a friend that uses and it works really well. It is probably the best paint out there besides the Biocop tf.
Cukote Biocide uses irgarol as the additional biocide and slime fighter, where as Biocop TF uses zinc omadine as the slime fighter.(just a little better performance)

Either way you can't go wrong...

Thanks

.

==============================

Bob I think you have it all figured out, but I might add this. There is only two ways that I know of that will provide a good adhesive bond between two coats of paint.

One is a mechanical bond and is what you are going to have to do no matter what and is achieved by sanding the surface and giving the new paint (barrier or bottom paint) something to get hold of. You need to sand with whatever grit paper the manufacture says to use for the paint you are applying.

The other is the chemical bond and is what you will have once you get that first coat of barrier or bottom paint on the present hull. That is the "hot coat". I've done a fair amount of auto painting and never heard the term used there. I'm not really fond of it since it might imply that somehow heat is actually used in the process. Maine Sail said....

Because it does not negatively impact the crosslinking and is what has been tested and proven to offer the best adhesion by the manufacturer. You can not however use a water based paint like hydrocoat hot coating.

The hot coat open time for epoxy to epoxy with IP2KE is weeks but only minutes to hours for paint to epoxy depending upon temp...

As he said a chemical bond is going to give the best adhesion between coats of the same type of paint (say additional barrier coats) or between different types of paint (say the first coat of bottom paint over the barrier coat).

Maine pointed out between coats of IP2KE it can be weeks, but just so you know that is not always the case for all types of paints. Sometimes it is hours, a couple days or maybe a week, so be sure and follow the directions of whatever you are using for a barrier coat and the bottom coats and make darn sure your are working with compatible paints (try and stay with the same manufacture for the whole process). You will have a lot of work and money in this, so try and follow the manufactures paint sheets as close as possible.

Sorry to reiterate the good advice you have already gotten, but thought it wouldn't hurt,

Sum

Our Trips to Lake Powell, UT - Kootenay Lake, Canada - Priest Lake, ID

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Maine Sail · Mar 10, 2010

BobM said:
The bottom paint is chipping off all the way to the barrier coat now, so no matter what I need to do something to get new paint to adhere.

It is chipping because it was not hot coated or applied correctly...

RichH · Mar 11, 2010

For me hot-coating ablatives only works for about 8-10 years, then I get the 'flaking'. I prefer Micron CSC on my saltwater boat.

I use either of two remedies depending on the severity of the flaking:

1. I sand and HOT water rinse the area of the flake and 'fair' the flake-crater using a large polyethylene trowel (may take several 'fills') and 'thickened' (micro-baloons, etc.) ablative paint. The final coat is straight ablative.

if the flaking area is large or the adhesion is now poor ... .
2. Get to a marina with a VERY high pressure - pressure washer. Hold the pressure washer wand at a LOW angle to the hull .... and *blow* the loose paint off the boat.

Id not deeply sand the barrier coat to apply new paint, just a 'scuff' with a coarse 3M 'pad' or 80 grit open-coat sand paper.