DIY Barrier Coat

[CaptKermie]

Originally Posted by deniseO30

interlux 2000E was what we used on my boat. The largest part of the job is removing the old bottom paint. I had it taken off with 50 grit. big job too! the bond is amazing! I'm just having problems with the new bottom paint sticking, my fault because we didn't sand the barrier coat. Any blisters, or fairing you should do before the barrier coat. it's rolled on, 5 coats is best. it sets up way faster then the instructions say it will. use small batches. We did under the stand locations with 5 coats first. the did the rest of the hull. It's all pretty easy tech wise. just long hours of sanding. good luck!

I did mine last spring, used the same product, 2000E. I read in the instructions that if you get the anti-fouling paint onto the epoxy before it completely dries, ie somewhat tacky, then the bottom paint will adhere without sanding the last coat of epoxy. You have to be fast though because the epoxy dries a lot faster than they say it does so you have to have the bottom paint stirred and ready to apply as soon as the epoxy feels tacky to the touch, sort of like being able to leave a finger print if you touch it but still not get paint on your finger.
This was not a job I wanterd to leave to the so called professionals because I do not trust them to be as fanatical as I would be. I was careful to do the best job I could and it took a lot more time than any pro would put into it.

[BarryL]

Hello,

I went through this in the winter of 2008. You can read about it here:

bottom paint 1, me 2, all done, test

Barry

[T37Chef]

Originally Posted by deniseO30

I'm just having problems with the new bottom paint sticking, my fault because we didn't sand the barrier coat.

Sanding is not needed IF you apply the first coat of bottom paint before the epoxy cures. If not than yes, you should sand with 60 grit

I disagree somewhat with Sailing Dog, I think you need to remove all the old bottom paint and get down to gel coat, after all the work your doing, wouldn't it be ashame for it to start flaking because you didn't get a great bond.

Of course my job is about four years old now with n sign of blisters reappearing, but I might be eating my words any day now

[pegasus1457]

Read the Interlux web site. There are lots of tips. Then read it again
I don't know where you are located, but the hull temp has to be above 50-something degrees, so it may have to wait until Spring.

Follow Interlux's time schedule for the 5 coats of barrier coat AND the interval between the last barrier coat and the first bottom paint.

Getting the old paint off: the best is soda blasting but it will cost you about $3K if prices on Long Island are any indicator. You can get it off a lot cheaper with marine paint remover, a good scraper, an orbital sander and a few weeks of hard work. Total cost: about $200 for supplies.

Good luck.

[T37Chef]

$3,000 !!!! WTF

I paid $580.00

[sailingdog]

Umm... exactly what are you disagreeing with??? I said to sodablast since it will take it down to the gelcoat...

Originally Posted by T37Chef

Sanding is not needed IF you apply the first coat of bottom paint before the epoxy cures. If not than yes, you should sand with 60 grit

I disagree somewhat with Sailing Dog, I think you need to remove all the old bottom paint and get down to gel coat, after all the work your doing, wouldn't it be ashame for it to start flaking because you didn't get a great bond.

Of course my job is about four years old now with n sign of blisters reappearing, but I might be eating my words any day now

[T37Chef]

Originally Posted by sailingdog

First, getting the paint off... If you have the budget for sodablasting the boat, I'd highly recommend going that route. Not only can it remove all the old paint, it will leave the gelcoat fairly well prepared for barrier coating, with only the need for a good washing. There is no need to sand down to the fiberglass.

Apologies Dog, I misread the last sentence above You are correct.

However, in my experience as shown in my photos above (See the first photo compared to the third photo), the blasting did not remove all the old paint, but then we were looking at many years of hard paint build up, maybe thats why I needed to follow the soda blasting with a lot of sanding, but it was certainly a lot less sanding then what I would have had to do if I had not paid a professional sand/soda blaster.

[deniseO30]

Thanks guys.. like I said.. I didn't sand before botom coat. there an echo in here? lol will sand it some in the spring... PROMISE!!

[bubb2]

Originally Posted by T37Chef

Apologies Dog, I misread the last sentence above You are correct.

However, in my experience as shown in my photos above (See the first photo compared to the third photo), the blasting did not remove all the old paint, but then we were looking at many years of hard paint build up, maybe thats why I needed to follow the soda blasting with a lot of sanding, but it was certainly a lot less sanding then what I would have had to do if I had not paid a professional sand/soda blaster.

I always thought even if you start with clean gel coat you sand with 80 grit and wipe down with thinner so there is some "tooth" there so the barrier coat can adhere better.

[Maine Sail]

#1 All paint should be removed, every last little bit.

#2 Measure moisture in substrate using a moisture meter. The hull should be as dry as possible before barrier coating. Proper drying can take months this is why it is a good idea to strip the hull in the fall, for Northern sailors, and let it sit over the winter. Coating a wet hull is pointless..

#3 Any blisters should be excavated filled and faired. I prefer to fair with a mix of coloidal silica/milled fiber/epoxy. Microbaloons are easier to sand but can absorb moisture, though under a proper barrier coat this should not be a big deal.

#4 fair the hull and prep for barrier coat. It should be as smooth as possible.

#5 Despite sanding you should still de-wax the hull with a chemical de-waxer like those from Pettit or Interlux.

#6 Choose your barrier coat. I prefer Interprotect 2000, as do many professional yards because it has long "hot coat" windows, is easy to use and comes in two colors so you can alternate and know your not missing areas.

#7 Always try and hot coat the layers of barrier coating. This results in a chemical cross linking and avoids sanding and washing between coats.

#8 You'll want to "hot coat" the paint to the barrier coat if using IP2K. The hot coat test is when you can leave a thumb-print, it is ready for the paint. You'll need two people as "thumb print" happens very fast, as soon as 15 minutes, so one guy will be rolling the last coat of IP2K and one the first pass of bottom paint. Hot coating the bottom paint is perhaps one of the most critical aspects of the job other than properly drying the hull. Do not skimp or miss your window on this or you'll be applying yet another coat of IP2K so you can hit the hot coat window.

If you need to sand and wash the hull you will not get the adhesion you get with hot coating. If you miss the thumb-print window simply apply another coat of IP2KE and don't miss it the next time or it will cost you another $100.00.

If you follow the above standard guidelines you will have a bomb proof barrier coat with phenomenal adhesion...

Above all else read the manufacturers instructions for temp and re-coat times..

This hull could have been slapped with barrier coat but the yard is doing this correctly and drying the hull. The drawings on the hull are moisture meter tracings with the dates and meter readings..


Many unscrupulous yards will gladly take your money and overcoat a wet hull. Any yard that says they can haul, strip, fair & barrier coat, South of CT where boats stay in the water for years on end, and do it in a "few weeks", without using heaters, is full of BS.

This unscrupulous money grubbing behavior is what has lead to many unwary boaters thinking their barrier coat was not water proof or failed when new blister appeared. The blisters & moisture were already in there but just trapped by a fresh barrier coat by a corner cutting yard. The moisture came from inside not outside..




From Interlux:

Originally Posted by Interlux

Note:Overcoating times will vary due to wide variations in temperature and humidity. The best method is to check the paint film using the "Thumb Print" test to determine when the Interprotect 2000E is ready to overcoat. If the primer feels tacky and you can leave a thumb print in the paint film without getting any paint on your thumb the Interprotect 2000E is ready for overcoating.

Continue testing every 15 minutes using the "Thumb Print" test until reaching the Ready-to-Overcoat stage, then begin to apply Interlux antifouling immediately.

Do not apply if the relative humdity exceeds 85% or if the temperature is above 95°F (35°C). Check primed surfaces using the "Thumb Print" test before overcoating with antifouling.

If you cannot leave a thumb print in the Interprotect 2000E or it is "tack free" it is too late to overcoat and must be removed. Follow application instructions on the antifouling label for overcoating times of subsequent coats.

Originally Posted by Interlux

Some Important Points: The hull must be dry. Do not apply over one part paints. Product temperature should be minimum 10°C/50°F and maximum 29°C/85°F. Ambient temperature should be minimum 10°C/50°F and maximum 35°C/95°F. Substrate temperature should be minimum 10°C/50°F and maximum 35°C/95°F.