I’ve been using Model Master paints for years now and usually I’ll add thinner to resurrect an older bottle of paint but it tends to change the viscosity too much. Has anyone here ever tried using Naptha or Acetone to bring an enamel paint back to life?
Not sure, but Acetone might melt your kit? It is rather aggressive…
I don’t use enamels anymore, but back a long time ago I found that artist turpentine tended to extend the life considerably. Heck, I even had some ancient Pactra military colors in the little square bottles with the P-drop logos molded on the sides that were still good 25 years after I bought them having added turpentine to them to thin them for hand-brushing.
Having said that, I have experienced complete breakdown of enamel paints that I added lacquer thinners to or which I thinned with Model Master airbrush thinner and then returned unused thinned paint back to the bottle. The pigments clumped together and when stirred up were just like powdery sand.
I think there’s a fine line when it comes to enamels (and perhaps other kinds of paint) where reducers and thinners can destroy the binders and carriers over a period of time. Once that’s happened, the paint is useless. On the other hand, once a bottle of paint has gone bad, there’s no harm in trying to see it can be brought back.
If the only problem with the thinned paints right now is that their viscosity is too low, you might also consider adding some amount of clear into the mix to add more binders and body. Color saturation / opacity might still be low, but the paint flow and usability might improve.
For glazes and airbrushed “filters” I add 5-10% by volume of clear gloss to the highly thinned paints to improve the way they bind to the surface and to make them spray smoother. I do this with both Tamiya acrylics (adding X-22 clear) and Floquil lacquers (adding Floquil Glaze). The glaze mix remains semi-transparent but the pigment remains in solution much better and the mixture also sprays much better.
Turpentine is an intresting thought, I hadn’t considered using that. I remember Pactra paints well, in fact I had the same grainy experience 100 years ago adding thinner to perk up a bottle, looked like it had corn meal in the paint, acetone comes to mind only because it’s one of the base ingredients. I understand that whatever I try will have to be used in fractional proportions. I stick with enamels because I like that it solves into the poly surface and bonds to the styrene. We’ll see what happens.
One way to test the compatibility is to put a small drop of well stirred paint on a solid inert surface
glass on top of coloured paper works, porcelain is good to. A white surface works for almost all colours except white/whiteish.
Add a little of the thinner to be tested to the drop of paint and mix it. Keep on diluting until the paint spreads out over the inert surface. If the paint thins and thins until it becomes “invisible” then the thinner works. If clots of paint start to form then it is the wrong thinner
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Well ya gotta love the internet. Turns out that Testors Model Master paints are part of a conglomerate that makes Rust-o-leum paint, DAP products and as I suspected, the former Pactra paints and PollyScale Floquill paints. It’s been my experience with MM paint that it will vaporize in the bottle after a long period of unuse or even during frequent use. If stored a very long time it will eventually dry of course and prematurely cure in the bottle. With regular use though it becomes essentially a thick sludge, the solvents (mineral spirits) and carrier (naptha) have gradually evaporated. Mineral spirits or thinner will dilute the paint but makes it too fluid to brush properly causing the paint (pigments) to wick into any fracture on the painting surface, naptha will reconstitute the base elements (talc and clay) and reinvigorate the texture of the paint to a creamy consistency. So though I haven’t tried it yet I’m confident naptha (lighter fluid essentialy) may acheive the result I’m looking for.
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Turpentine would have been my recommendation here.
On the other hand: Please do NOT use Acetone. It is very aggressive towards everything that will be in contact with your paint. It easily destroys the rubber sealings in your airbrush, wears down your brushes quickly and if overdosed even damages the surface of your plastic model. Vapors are also harmful enough not to be used in closed rooms too much…
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I hadn’t thought about using lighter fluid as a paint thinner in a long time (since I switched to acrylics years ago), but, back in the old days before hobby paint makers started seriously pimping their own proprietary brands of thinners, lighter fluid was the go-to thinner / brush cleaner for model paints.
(Even used the lighter fluid thinned muck in the bottom of the brush cleaner bottle as a wash… 
)
I mentioned using turpentine as a thinner above, but, now looking back, I recall that I first tried that back in the '70s when I ran out of lighter fluid and resorted to raiding my sister’s school art supplies and swiped her bottle of turps.
I went back to lighter fluid as soon as I could, but continued to play and experiment with the turps to aid in blending hobby enamels on figures. (Which, ultimately led to me experimenting with adding white and black artist oils to my hobby enamel pallet to extend the drying time of the enamels as I learned to blend them better - all of which started me on the path I now follow with painting figures in oils… )
Sometimes I feel sorry for a lot of modelers these days who don’t get to experiment and learn like we were forced to back in the day (as I sit on my porch and yell at the kids to get off my grass! 
)
Ah, the happy, innocent days of model building… 
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Have you tried Testor’s Universal Thinner?
I’ve read of some using regular (not fast evaporating) lacquer thinner.
I’m still using Floquil Dio Sol.
I use that exclusively to thin and clean brushes and the airbrush but it’s mineral spirits and solves the paint too much, I brought home some naptha today but jumped right into building and haven’t had a chance to try a mixture. I don’t know the specific petroleum properties of either agent but somehow they react and become more viscous. Kinda like adding alcohol to white glue, it becomes clear and gelatenous. Naptha is one ingrdient of napalm so hoping for the same effect somewhat but more creamy for lack of a better word.
FWIW - Most of my enamel experience is with Folquil/Floquil Military/Humbrol and only a little with Model Master. Lighter fluid aka naphtha and xylol/xylene are still my go to thinners for those paints.
Best Guess…
The old Floquil Dio-sol thinner would be my go to thinner if attempting to bring back a bottle of enamel for one last use. I think it was pretty close to half toluene and half xylol. If Dio-sol isn’t available I’d probably try a 50/50 mix of naphtha and xylol if attempting to bring back a bottle of enamel for one last use.
Wish you the best of luck with the restoration.
Please be safe and have excellent ventilation if using any of the solvents. If spraying, a respirator with the proper filters to filter out particles etc regardless of if the paint is enamel or acrylic is wise.
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Not that it matters unless a stash of Dio Sol is available, but for the record I used Dio Sol for Model Masters, Humbrol and of course Floquil without issue for both hand brushing and airbrushing.
Resurrecting old paint was always iffy. Once it turned to rubber throughout (not just a surface skin) it got tossed in the trash.
Life was much simpler and I guess more toxic back then.
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I have resurrected jellied Humbrol using balsam turpentine
Well I did some hand brushing this evening and used the naptha to slightly thin the paint and it worked well enough but still not the texture I want for using a bristle brush, looks like I’ll have to get my hands on some turpentine and give that shot. Fact of the matter is I really don’t like to hand brush, I normally lay out every peice I can get taped down and spray every thing of a like color, the paint just lays down better, but some detail brushing is unavoidable. It may be I need to hand brush the tiny peices and then shoot those parts with clear flat in order to get a more apealing surface. Thanks to everyone that offered their experience and suggestions.
Turpentine comes in different brands/mixtures so test it properly first.
I jellied Humbrol with naphta and then revived it with turps. Then I used another brand of turps and almost ruined another tin …
Maybe the best thing to do is just buy some new paint hunh 
, at five bucks a pop though that get’s costly, this aint a poor man’s hobby 
. Ta!
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Follow up -
Ended up with a split seal in a bottle of Floquil Military Color Dirt enamel and didn’t notice it. The paint in the bottle evaporate down then cured into tar.I tried a little Floquil Military Color thinner which didn’t help much. Likewise with naptha. However, 6cc of Xylol and it stirred back into paint.
The resorted paint was moved to an empty Tamiya bottle with a good seal. It’s suitable for careful brush application & washes. I wouldn’t attempt to airbrush it unless it was strained. I’ve used it a flew times over the last month.
Xylol appears to work for at least briefly returning enamel paint to life…you will want EXCELLENT ventilation when using Xylol.
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Interesting! I have many Floquil bottles in that same “rubber in a jar” state.
Did you revived paint lose opacity and did it dry flat (matte)?
The paint in question lost some opacity due me adding 4cc of FMC thinner, probably 4cc of naptha then 6cc of Xylol. That’s basically 14 cc or 14 ml of thinner to probably 8cc of paint tar/rubber.
It stayed “flat” overall, however thinning it out even more for making a wash it picked up a little sheen. The clear flat took it back to dead flat.
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