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mikehoyt 09-27-2004 05:08 AM

Best way to remove barrier coat
Trying to get a head start on 2005 season before the weather turns.

I have thoroughly pressure washed hull and keel to remove most of this years Antifouling and am now ready to remove the remenants of 5 year old VC17 and Interprotect (most of the VC17 is already gone from previous years sanding).

What is best procedure to get the hull to bare fibreglass? What type of sander is best for this as it seems to be a daunting task?



Full Tilt 2

aflanigan 09-27-2004 08:36 AM

Best way to remove barrier coat
I think good old boat did an article recommending "soda wash", a blasting technique using bicarbonate of soda. Effective and very friendly to the environment. I have also seen water/sand blasting recommended. For DIYers, your options are sanding or chemical strippers. According to Don Casey, there are chemical strippers available that are compatible with (i.e. won''t destroy) the fiberglass under the paint.

Allen Flanigan

aflanigan 09-27-2004 08:53 AM

Best way to remove barrier coat
It sounds from your message like you are taking on this task yourself.

Probably what I will do when the time comes is try chemical strippers to see how well they can take off some or most of the existing coatings. Hopefully, what''s left can be carefully sanded off. You can rent a vacuum sander from a rental place (house painters use them on big jobs, I guess), but they don''t have the ability to take off a lot of material quickly like a high speed disc sander. Plus they are somewhat unwieldy (they have a power head attachment and a vacuum hose to heft) so your arms will tire after a while. Hopefully, most of the spots on the hull will require a light sanding with the vacuum sander; for stubborn spots you can do it with a disk sander (be sure to wear a good respirator), make sure you''ve got a drop cloth to catch the toxic dust. You''re right, it''s going to be a daunting task, I''ve never done it but I can tell just from how much work it was to do a "quickie" sanding and repainting job last spring on the trailer.

Allen F.

mikehoyt 09-27-2004 10:27 AM

Best way to remove barrier coat
Thanks Allen

I had talked to Interlux Technical support and they said that they have no product to remove their Interprotect barrier coat. They suggested sanding.

As there is almost no antifouling and just the barrier coat I am leaning toward sanding. Having sanded two seasons ago to smooth this coat I realize it is not going to be fun.

What exactly is a "vacuum sander"? I am wary of using a grinding disk as that can damage the hull as it is so aggressive. Maybe I am wrong on this?

Thanks again,


.. and thank goodness it is only 26 and not 40 feet!

hamiam 09-27-2004 10:42 AM

Best way to remove barrier coat
stupid question but why do you need to remove the barrier coat that is there? on another note a product called peel away comes in different formulations one of which removes only the antifouling and one of which removed both the antifouling and the barrier coat. (According to them.)

Jeff_H 09-27-2004 01:10 PM

Best way to remove barrier coat
Sanding an older boat to the extent necessary to remove the barrier coat is a really bad idea. That kind of sanding produces a lot of heat which can trigger a break down of the resins deeper in the laminate. This provides a mechanism for deeper blisters and delamination to occur. Barrier coats provide not assistance in preventing this kind of blistering.


mikehoyt 09-28-2004 03:32 AM

Best way to remove barrier coat
Good point Jeff.

What I am looking to do is to remove the flaky portion of this underlying coat and apply a smooth new coat and then a fast paint.

Since the boat originally had VC17 when I bought it I am guessing the underlying coat is something like Interprotect. It is a tan colour.

If I could sand it down thin enough to fair any rough edges then I would be happy to apply another barrier or leveling coat to achieve the smooth surface. This would then allow me to apply a thin fast paint in the spring. (the levelling/barrier coat would also be applied in Spring).

I have been using Komposite KL-990 for past 4 seasons. It is an ablative that overcoats old paint and comes off easily. Each season I pressure wash (a lot) to remove current year coating and any flaking old paint/coating. Two seasons ago I also sanded (a lot) the old coating smooth after pressure washing so there is not a lot of it left.

Our water is warm in summer (65 - 73 deg) and relatively clean. We get some slime but the boats generally come out very clean with no grass.

This next year I am hoping to go with something faster such as VC Offshore since it is a saltwater environment. Wish to have the hull and keel prepped properly for 2005 season. I want nothing below the waterline to be less than it should be for a race prepared boat.

Big problem is that every year when applying the new paint the old coatings will flake off in some areas. Even after spraying/scraping and sanding.




mikehoyt 09-28-2004 03:35 AM

Best way to remove barrier coat

Do you have a link or contact info where I could find peel-away?

Want to remove it because it is not adhering properly. Suspect this coat was a levlling coat rather than for blister protection as this boat came from Fresh water 4 years ago.


hamiam 09-28-2004 04:07 AM

Best way to remove barrier coat

aflanigan 09-28-2004 06:17 PM

Best way to remove barrier coat

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