Tru Color paint behavior

[nickelplate759]

I tried a new Tru Color color this week - Aluminum.

It didn't behave as expected.  In particular, it seems to behave like an an overcoat - even a heavy application (and yes, I mixed it well) didn't obscure the underlying color (a mix of black and white styrene parts).     Does anyone know if it requires a specific undercoat, or did I just get a funky bottle?   Tru Color Silver, on the othe rhand, will cover anything.

Other than color coverage, the paint behaved just like any other bottle of Tru Color.

[ednadolski]

Over a mix or black + white surfaces it seems that a primer would be advisable regardless of the top coat color.

Ed

[nickelplate759]

Agreed, but for this aluminum paint, what color primer?

[Ken Martin]

I have read that you need a glossy Black as a primer for aluminum

[peteski]

That's odd George.  Silver particles are opaque, so they should cover well.  Are you sure that what you are seeing is not the base layer of paint partially dissolving, getting infused into the silver paint?

I've been using Accu Pants for decades, and never had a problem with Silver/Aluminum paint's opacity. Yes, I know that you are using Tru Color, but those paints are very similar.  I still have a decent stash of Accu Paints, but since they are long discontinued, I bought a bottle of Tru Color Silver paint, but I'm not sure if I actually used it on yet.

Hopefully someone here will have a definite answer for you. If not, I could try my Tru Color Aluminum and see how it behaves.

[nickelplate759]

I agree that it seems odd, that's why I posted my query.  Again, Tru Color silver seems to cover anything without difficulty, but aluminum, while it has metal particles in it, seems not to cover very well.   I have tried it over black, and it comes out darker than I would expect aluminum to look, but the finish does appear somewhat metallic.   Stirring the bottle I can see both silvery and black pigments.

[peteski]

I agree that it seems odd, that's why I posted my query.  Again, Tru Color silver seems to cover anything without difficulty, but aluminum, while it has metal particles in it, seems not to cover very well.   I have tried it over black, and it comes out darker than I would expect aluminum to look, but the finish does appear somewhat metallic.   Stirring the bottle I can see both silvery and black pigments.

I didn't realize  that Tru Color has separate Silver and Aluminum colors available.  I just have their Silver, Dark Aluminum (which to me looks like stainless steel), and Galvanized Metal (another dark silvery color).  I have not tried those 2 former colors yet.

[Steveruger45]

According to this, no primer necessary.
https://hennings-trains.shoplightspeed.com/tcp-013-aluminium.html

[ednadolski]

Agreed, but for this aluminum paint, what color primer?

I should think a typical primer gray would be fine.

@peteski  I take your point about the metallic particles but I think you're making a presumption about the specific chemical composition of the paint in this case.  The name of the color isn't a reliable indicator of what the manufacturer actually puts into in the paint.

That said I've used the TCP aluminum and found that it covered pretty well, tho in my case I did use it with a primer.

Ed

[nickelplate759]

According to this, no primer necessary.
https://hennings-trains.shoplightspeed.com/tcp-013-aluminium.html

That's the boilerplate that applies to Tru Color paint in general.  It's true - the Aluminum paint adheres just fine on plastic with no primer, but the Aluminum color doesn't LOOK fine without a primer.

[peteski]

I'll have to pick up a bottle of their aluminum paint to see how it behaves.

The manufacturer themselves states that those paints can be applied directly to plastic.  From https://trucolorpaint.com/color-charts/chemistry/

All paints are composed of pigments and/or dyes held in a binder (polymer) which adheres to the item being painted suspended or dissolved in a liquid. Some paints are water based (latex type), enamels (lacquer base) and some are solvent based. Polymers used to produce paints can be acrylics, rubber (latex), epoxies, urethanes and various others. Polymers form the matrix that the pigments/dyes are dispersed in that allows the color to “stick” to the item being painted. Without the polymers (which by definition are “plastic”) the pigments/dyes would rub off.

Tru-Color Paint is a solvent based paint with an acrylic polymer used as the binding agent which adheres very well to plastic or metal models, when those models are properly prepared. The pigments and/or dyes used to produce the correct colors are very finely ground so that they do not clog air-brushes.

To insure proper adhesion for plastic models – wash the model in mild soapy water to remove residual processing oils and dirt, rinse thoroughly with clean water and let dry or use a lint free cloth to dry. It is now ready to be painted.

For metal models (brass for example), sand blast or treat the metal surface in some fashion to give Tru-Color Paint a prepared surface to adhere to. Then use our Primer, Tru-Color Paint 007 or 256, and spray paint the model, allow sufficient drying time and then paint the model with the desired color(s).

[nickelplate759]

While we are digressing to the usability of Tru Color paint in general, I'll mention that while you can clean it up just fine with Acetone,   Acetone alone is not a good thinner for this paint (I tried, 'cause I'm cheap and so is Acetone).   Acetone will definitely thin it, but the paint will dry too fast and I couldn't get a good finish.

I'll also mention that the plastic bottles that Tru Color comes in seem to allow slow evaporation.  Even hitherto unopened older bottles have appeared half empty and too thick to spray well.  Easily remedied by adding Tru Color thinner (again, not just Acetone).   In my experience, when spraying Tru Color paint, thinning to the right consistency is more critical than the air pressure adjustment.

[peteski]

I agree with all you mentioned George. It all applies to both Tru Color, and Accu Paints.  That is why the first thing I do when I buy a new bottle (that has not been sitting on a hobby store shelf for months) is take move the paint from the plastic bottle into a Floquil glass bottle with a home-made aluminum gasket in the cap.  That prevents most of the solvent evaporation. I also use a fine permanent marker to mark the paint level and month/year  on the bottle to monitor evaporation. I just took one of those Accu Paints I last sealed in 2001 and the paint level dropped only about 1/16" below the line I marked 19 years ago,  Paint is still good.

Like you mentioned, straight acetone is not a good thinner.  @u18b had a good write-up about this in one of his build threads.  The "real" thinner for those paints contains acetone and other solvents with much slower evaporation rate (like ethanol, MEK, toluene, propyl alcohol, diacetone alcohol or butyl ester acetic acid).  These chemicals were mentioned on some of the paint labels.

TCP also now sells retarder to slow down the evaporation rate even further.

I have a theory about the solvent evaporation in the plastic bottles.  I suspect that it is mostly acetone that evaporates from those bottles (due to its volatility). The slower-evaporating substances are likely still left in the bottle. So, when replenishing the solvent that evaporated from the plastic bottles, I would just use acetone.  That's what I used to do before I learned to move the paints to those glass bottles I now use.

[u18b]

I switched to Tru-Color for the second EP-2 I built (as Peteski indicated).

Somewhere somehow.... I had heard or got it in my mind that it was thinned with Acetone.

It was a disaster.  Acetone dries WAY to fast and the end result is a powdery look.

I now use lacquer thinner.   May not be the best thinner, but I get good results overall as long as I don't paint with it on a windy day (which you shouldn't do anyway).

[u18b]

The horrid details of using Acetone start on page 13.

https://www.therailwire.net/forum/index.php?topic=36215.msg488334#msg488334

So bad I stripped the paint and started over.

Lacquer thinning results on page 15.

https://www.therailwire.net/forum/index.php?topic=36215.msg495956#msg495956