OK, I admit, despite all other paint brands on the market… I still use a lot of Humbrol enamels. Probably because I grew up with it I feel most confident that the end result is going to be fine.
But I HATE (with a vengeance) those miserable metal cans, and the process of thinning for each small airbrush job is rather time consuming.
Next to that I have some empty alclad bottles so…
… does anybody have experience with pre-thinning Humbrol (or any other paint for that matter). I mean taking a new can of Humbol, pour it into a larger bottle , mix it with thinner to make it airbrush ready?
If so, does that work and does that mixture hold for a long (i mean years) time?
If the new jar is air-tight enough to prevent the gasses getting out I don’t see a problem. If you use Humbrol thinner it’s the same stuff they already added to the paint in the first place! You may need to mix it before use, as the solids will tend to precipitate out, but the same goes with unthinned paint in the tins so nothing new there. Give it a try with one tin (that you can easily replace) and let us know how it goes!
I used to use Humbrols years ago before I went acrylic, then abandoned those for Tamiya and AK RC with lacquer thinner. Now I’m a happy boy.
I have pre-thinned Humbrols many times. It is a legitimate endeavor. Not only do you get rid of the hard-to-keep-airtight tin, you have airbrush ready paint all the time. With Humbrol thinner or mineral (white) spirits, I have had pre-thinned paint last five years with no problems.
A few months back, I began doing this with Vallejo Model Color paints. Thinning paints to the correct consistency in advance completely eliminated one cause of really bad airbrush clogs. I no longer throw out used paint bottles. They all get recycled to hold properly thinned paint.
I also save mid size bottles. When I purchase a big bottle of Flow Improver or whatever, I put some in a midsize bottle for actual use. The smaller bottles are much easier to control when dispensing paint products by the drop.
You can do this so long as you use a compatible solvent. However, there is a caveat: Most paints are formulated with a specific ratio of pigment to binder (the film-forming element, to solvent. Additionally, the binder can be specific to a particular pigment, requiring a different solvent or solvent ratio. What this means is that pre-thinning may not work as well for some colors in a specific paint brand.
The usual problem with pre-thinned paint is hard settling. But what is settling is not always just the pigment. The binder may do so as well over time. In such a case, you may get an undispersable blob in the bottom of the bottle. Or you may shake it up and it may seem dispersed, but the binder will no longer form a proper film, and you get severe dusting of the paint.
I advise you not to do this with gloss metallic paint. Metallic pigments are completely different than others, and generally require very specific formulations to remain stable over time.
I also recommend adding a stainless steel ball or two, to the pre-thinned paint. This will help a lot with redispersing the components, just like the aggitator ball in a “rattle can.”