Paint colors.

I cring to ask this for the wrath that I could bring down upon myself, but.....

Has anyone considered coloring their topsides paint with coloring components from your local superstore chain?

To expand on the thought: Would the coloring components be compatible with say... a white topsides polyurethane? I doubt that the store would even consider coloring a can of paint that wasn't theirs and it sounds risky at best. I'm most likely going to purchase two cans of topsides paint and mix them to get a color that I want. White and yellow to get a toned down, softer yellow.

 

we used to have a agent for gel coat. try calling the maker of the paint your using and ask them if they have some made for that paint.

 

Risky at best. Find a Marine paint supplier, many have mixing machines.

 

I often took PU and PA paints to my paint mixer to modify an existing colour in a premixed tin of paint.

That said, I also often coloured gelcoats and GP polyester resins with PU 2K twin pack paints, but not adding the 2K hardener but using the MEKP instead before applying to mold.
Have sample pieces lying outside in the sun for about 4 years now with no discoloration, lamination etc problems. This method is useful when gelcoat needs to be a fancy custom colour

 

I have to laugh(at myself). I'm not sure that I understood any.... well, much of anything you just said. Your light years ahead of anything I might be doing, but all the same, I do appreciate your input. I've not ventured into two part paint systems, though they may someday if I can ever get to a serious build.

I went to my marine paint supplier today and they looked at me funny when I asked about custom mixing. I didn't care to buy two quarts to mix a pint of the color I was looking for for, so I just opted for a stock color that was in the realm of things.

 

Not only do you need to be concerned with what the actual pigments are made from, but also the carrier it's blended with.

There are pigments that aren't suitable for use in polyester gel coat, some can rapidly shorten the shelf life (not much of a problem if you're using it right away) and others that can kill the cure.

If the carrier (liquid the pigment is blended with) isn't compatible it can create problems too.

We do a great deal of testing before approving a new pigment for use in production.

Frequently, even if the products aren't too compatible, not enough is added for there to be a noticeable issue, it doesn't mean it isn't there, you just don't see it short term.

I assume this would be the case with just about every type of paint or coating. You may be able to do it and have no issues 9 out of 10 times, but eventually you will find a pigment, or combination of pigments that do odd things.

 

I've mixed paints for years with no issues. The key is to use the same type of paint. Alkyds with alkyds, modified acrylics with the same, LPU's with LPU's. It seems reasonable enough but anything else can be risky. This said, I've used alkyds to modify LPU's, though you have to have a pretty good idea what you're doing chemically. For example high cyanoacetate content polyurethanes don't mix well with alkyd additives, but low acetate mixtures work fine. Comparable vehicles are required naturally and an idea of pigment type is helpful too. So, if you're a bit unsure about these sort of things, then just mix different colors of the same brand and type of paint, you'll have no problems. In short, if you're using Brightsides and want a teal they don't have (as an example), then mix 50% medium blue with 50% medium green and tone it down with some white (if desired), all of which should be more of the same Brightsides.

 

Over here we have several types of pigments, (for acrylics, for LPUs, for epoxy, for polyester)

Some can do funny things. We have a white pigment that can completely stop cure if you are not taking measures, for instance.

In general it is not a good idea to blend things, chemically wise. On top of that, pigments that are in dispensing machines are thinned down, as the pumps in these machines cannot handle high viscosity pigment pastes. Therefore you add a lot of base product as well, which is no problem if it is the same chemistry, but if it is something else...

And then there is the problem of getting the right colour. Most dispensing machines work with at least 2 base paints, a white one, for light tones, and a transparent one for dark tones. This saves dispensing a lot of white pigment. Keep that in mind when putting a non-certified can of paint under the dispenser.

 

Agreed, you have to have a clue, but it's possible with some understanding.

 

Polyurethane one-pack should be OK to tint with "universal" colorants from paint shops, but 2 pack, no. I have tinted polyurethane one-pack without any dramas, but not in marine applications.

 

You wil need to know what base is used. DIY tinting paste for latex paints is water based. We use it in our acrylic systems without problems (at least it is not the water that can create problems, but the pigment itself can do fun things as well)

The tinting pastes for exterior paint usually have a hydrocarbon base, and can be succesful in resins. These usually are dispensed in colour dispensers, not available in small tubes.

 

One of the most inventive paint tinting experiments I've seen involved a chap tinting some white enamel to a grey using black molasses, to disguise some rust in a car door. Incredibly, it seemed to be successful.

 

Hmm, in that sector I have used corn starch (Maizena) for making fillets with epoxy, and white shoe shine to disguise pinholes in a white sprayed carbon part.

The shoe shine might make nice pigments as well...