Bottom paint failure cause?

[JamesG161]

I just put the garden lime in the PVC bucket, add water with stirring... then add the KOH... about two to three cups worth. Probably could just dump two cans of drain-o....I don't think it matters what you use to keep the paste moist. I have even let it dry without a cloth and just re-wet it with a light mist using the "thumb over hose end" approach a few times before blasting it off. And I have used plastic sheeting and once an old tarp. I think the commercial stuff uses sheets of wax paper.... so maybe an old news paper would work also. The nice think about burlap is that it strains the mess when you blast it off... so you can catch all of this toxic paint for proper disposal.

I read you paint application spec. At no time did they use this mixture.

Merely scuffing the paint is often not enough when switching paint types. The directions needs to be followed to a tee..

Listen to Maine Sail...
Sorry there is not an easy way to recover/renew that bottom.
Jim...

 

[Gunni]

That grey color with roller fur nubs sure does look like Interprotect epoxy barrier coat and it is not bonded to the first coat of bottom paint. Sorry to say it looks like you MAY need to take it back down and start over. I would begin with barrier coat to make sure you have the laminate sealed up. When using HydroCoat note that it can be thinned if you are just doing a yearly refresh. Don't let the paint build up - full strength at the waterline and on the leading edges of hull, keel and rudder.

All that said, you can scuff and paint the bare spots, monitor the situation for a year or so and see how things develop. It may not be a widespread problem.

 

[rgranger]

I read you paint application spec. At no time did they use this mixture.

Home made "peel-away". No specs to read...

 

[Brian S]

Zest is the finely grated off skin of citrus. You can get a "zester" at the grocery store which just looks like a finer grater than you'd use for, say, parmesan cheese.

 

[njlarry]

Thank you all for all the help! I believe that only the starboard quarter is currently affected. I will get a better look next time we visit her. I may strip just that area or spot treat with sanding to see what happens. This spring was supposed to be the time to work on the decks.
If we have to strip the entire hull and apply new barrier coat, would there be any harm in soda or walnut shell blasting?

 

[woodster]

soda blasting is a very good way to go ..and its quick

 

[rgranger]

Zest is the finely grated off skin of citrus. You can get a "zester" at the grocery store which just looks like a finer grater than you'd use for, say, parmesan cheese.

Thnx

 

[Gunni]

When I did this job I hired a guy with lots of experience to sand the bottom, barrier coat, and bottom paint - all old-school. The price was about what I would have paid to have it soda blasted but I was concerned that compressor oil would complicate my adhesion problems. If I do it again I would have the hull blasted and just carefully specify compressor specification.

I scuffed and painted my barespots for a couple of years while I researched my options and managed my boat budget.

 

[Scott T-Bird]

If I do it again I would have the hull blasted and just carefully specify compressor specification.

What is the issue with compressor oil? Is there a mist that gets mixed into the removal process? My bottom is getting soda-blasted soon (possibly this week) and I didn't think anything about it. It will be left bare until the spring when the painting will be done. I would think that if there is any residue, it can be addressed in the meantime?

 

[Gunni]

Industrial compressors are oil-lubricated just like a motor and if the compressor is worn there will be oil blow-by around the piston rings or rotor bearings. There are elaborate oil coalescers that should be used other wise your hull will get a coat of compressor oil that must be completely removed prior to applying bottom coatings. Ask your tradesman how he manages this issue. At the very least, you will be using lots of clean rags and lacquer thinner to wipe down the hull prior to coating.

 

[rgranger]

Industrial compressors are oil-lubricated just like a motor and if the compressor is worn there will be oil blow-by around the piston rings or rotor bearings. ....

This is also why you have to use special compressors for diving. You don't want to breath that oil mist.

 

[Scott T-Bird]

Cool, I'll have to ask about it. I can imagine the quizzical look I'm going to get and some kind of smart-ass reply. At least I'll have the winter to clean it if there is an oil film and then I can decide if I trust them to paint! I'm definitely going to ask them about hot-coating the 1st ablative layer over the new barrier coat.

 

[Gunni]

If you just look at most blaster's gear you can tell if they sweat the details and are professional. One guy down our way works out of a trailer that looks like a NASA clean room. He charges more and I hear he is worth it. I had my guy put down a first coat of hard ablative in a contrasting color, hot coated. Then when my soft ablative wears down I still have anti-fouling.

 

[JamesG161]

At the very least, you will be using lots of clean rags and lacquer thinner to wipe down the hull prior to coating.

According to Pettit Paint, he is using you should do this anyway with this.
http://www.pettitpaint.com/product.asp?id=233

Laquer Thinner is not the same thing but would probably work too.

Both help to remove oil, grease and WATER.

The paint should go with in an hour on a low humidity day.
Jim...

 

[Warren Milberg]

To me, bottom paint failure is almost always caused by poor surface preparation. Too much paint build-up, moisture in the hull, or using incompatible paints (hard over soft - failure to fully remove previous paint) are the primary causative factors.