Hard Bottom Painting: Blending Different Brands (Or Not?)

[rardiH36]

An employee of one well respected boat yard commented "no problem" to stir together modified epoxy hard paints manufactured by different companies. Rational: All have the basically a similar underlying formula. Another well respected yard suggested this not a good idea. Rational: Don't know,but just not worth the risk of failure.

I'm wanting to know because this modified epoxy high end 67-70% cuprous oxide stuff is really expensive. I have on hand a couple of gallons and a few quarts in different colors and different brands, which I picked up at "last can in stock" discounts averaging 75% off even the best "on sale" price.

What's the forum's opinion? Should I paint a coat (or partial coat in the case of quarts) with each can sequentually, keeping one of the gallons for last to ensure the final coat being uniform in color? Or is it OK to pre-mix all of the paints into one color? (Would be a nice navy blue.)

One thing that I've researched is to look at the MSDS sheets of each manufacturers' recommended thinner. The MSDS sheets specify in gross terms the chemical make-up of the thinner. I've found that each thinner might have somewhat different percentages (generally expressed on the MSDS sheet in very wide ranges), but all are primarily a blend of naptha, benzene (in the form of xylene) and mineral spirits.

All my life I've blended similar paints for around the house. Never encountered an obvious failure as a result. But also never blended a paint that needs to protect a hull under water for a few years.

 

[woodster]

dont know about the different blends....but every time i mix odd paints the color seems to always come out some sorta brown in color...lol...

regards

woody

 

[BobM]

For a hard paint it won't be what the solvent is that counts. It will be whether or not it cross links and hardens or not. My suggestion is to make a rough blend on a small scale and see if it does so. If it does, go for it...just remember that you are the one who gets to strip a 36 foot hull if it doesn't work LOL.

I don't pay more than $110 a gallon for Pettit Hydrocoat water based multi-year ablative (and I've let it go two years) and works fine for me.

 

[rpwillia]

A slight variation

I won (yup you heard that right) a gallon of the new Pettit ablative bottom paint. Typically when I haul I use 2 gallons and do two coats. Since I usually use WM brand and it works fine (upper Potomac is fresh water), could I haul out, sand and paint the first coat with WM and then follow up with a 2nd coat of the Pettit.

Since we typically paint over whatever paint is on there, I don't see a problem. I suspect at the end of the day most paint is paint. I think I would mix real good and go for it. If you would use each one of these on it's own the formulation is probably OK.

 

[All U Get]

Wild side...

Last year I had some left over red and a gallon of black. Since I had to wait for the yard to move the jack-stands, I had red and black squares on the bottom. Only the fish could see it until we were heeling over on a cruise. People on other boats were staring at us, etc. Maybe this year I'll paint "If you can read this, send the Coast Guard".
All U Get

 

[Warren Milberg]

Couple of years ago, I ran into a guy in my yard doing spring maintenance. He had a number of quarts of differnt brand leftover bottom paint. Rather than mix them, he painted his rudder with one, his keel with another, and the hull with yet another. Only the rudder was another color. He said he thought this was good way to use up leftover paint. I agree and may do the same thing with my boat next year.

 

[sailingdog]

This makes far more sense than mixing the paints, which may or may not be compatible.

Couple of years ago, I ran into a guy in my yard doing spring maintenance. He had a number of quarts of differnt brand leftover bottom paint. Rather than mix them, he painted his rudder with one, his keel with another, and the hull with yet another. Only the rudder was another color. He said he thought this was good way to use up leftover paint. I agree and may do the same thing with my boat next year.

 

[Barnacle Bill]

To be safe, I wouldn't recommend mixing different brand paints. Each paint company has a compatibility chart and it probably would be better to paint one brand OVER another brand (rather than mixing them together) assuming they are compatible. If you go places you haven't been before, then you have to consider that the outcome might be bad and that will end up costing you more money, time and frustration.

 

[rardiH36]

Everybody:

Thanks your good comments about factors to consider. Also good humor in some of the posts.

I'm going with the advice not to mix the paints. I opened the various cans for the first time last night. One of the brands smelled very different than the other two. If nothing else, that's a warning that the formulation of "modifed epoxy" between the brands does vary and its not worth the risk of failure to mix them together.

So my plan is to use the couple of quarts of Paint A for the rudder and maybe a first coat for the keel area. The gallon can of Paint B will do two coats on the starboard side. The gallon can of Paint C is the slightly higher end paint. Accordingly I'll use it for the port side which gets more marine growth at the water line because my berthing orientation puts the port side to the sun.

Brand B and Brand C are different hues of blue ... but that shouldn't be noticeable when separated by the center line. But it will be obvious to another other boats coming towards me at an intersect course that if its the the darker blue side that is showing, then they are to be the give-way vessel.

 

[BobM]

Another good use for partial cans of paint is painting the bottom of the dinghy. Some standard ablative paints (typically the water based ones) are also compatible with inflatables, such as Pettit Hydrocoat.

Personally I think you should have some fun with it. Paint a Shark mouth on the bow under the water line ala the Flying Tigers P-40's...or paint a whole Shark. Think of all the creative things you can do! I should paint "If you can see this my Wife is at home" LOL.