Hello,
I am trying to figure out what is the best ratio for thinning Tamiya paints when airbrushing. In the past I have thinned Tamiya paints with Gunze Mr. Color thinner and have gotten beautiful results with dead flat finishes.
I know some like to thin at 50/50 ratios, but I do not want to apply multiple thin, translucent coats.
Thanks
I airbrush almost exclusively Tamiya paints and find theyāre extremely forgiving. I tend to go for a 50/50 mix at about 18 PSI through a 0.3 needle and never had any problems. Thatās using the x20 thinner as well. Many suggest Tamiyaās lacquer thinner as even better.
Iāve not noticed the 50/50 mix is particularly translucent and rarely have to worry with dedicated primer, just use a black/dark grey Tamiya as a shadow coat. That said like any manufacturers coverage does vary a little between colours.
Never had a coat that isnāt durable. Iāve noticed on the odd occasion accidentally set air pressures havenāt seemed to make much difference at least for base coats.
Given their ease I would suggest working back from a 50/50 mix to gain the opacity youāre after, maybe 60/40?
There is no hard and fast formula. The ratio is dependent on many variables including type of AB. spraying pressure, local conditions of temperature and humidity, and even paint color. Having said that going with @D1GG3r321 suggestions would be a good starting place for you. Best to experiment a bit to find what works best for you and what you are comfortable with. Good luck.
I also recommend Tamiya Lacquer Thinner (yellow top bottle). 50/50 is a good place to start, but as Armorsmith says, there are a lot of variables involved, so you would have to experiment to see which mix/psi works for you. Clean-up is also done with the same lacquer thinner.
Good call on the lacquer thinner as I forgot to mention that.
Thanks everyone for responding. I will definitely take everything youāve said into consideration when thinning Tamiya paints. I really liked the finish I got using Mr. Color so I will probably stick with that.
Brian
I will second the lot of variables required. My house is very dry in the winter so I need something more like 70% thinner
Something Iāve found useful if you have an old kit you arenāt proud of sitting around is to test your mix on it. Thatās what Iāve been doing before anything goes on my kit
In the winter here in Oregon, I always go 70% thinner, 30% paint @ about 18 psi. Goes on super smooth and never clogs. In the summer with more humidity I drop it to around 50/50. I love Tamiya acrylics in my airbrush. Vallejo Model Air on the other handā¦I felt like slamming my face into a wall despite trying out every trick in the book to make them not dry so quick on the needle. But thatās a whole other topic and a lot of paint sitting on my bench unused. 
They say real color is just like working with Tamiya but has a greater color choice. I have ordered some with their thinner but havenāt used it yet.
Real color is almost identical in working properties to Tamiya in my limited sample. (Iāve used about 8 different colors so far). Mr Color is similar, but seems sensitive to the amount of thinner used. For all of this I use Mr Levelling Thinner to thin. And to the OPās question, I usually am at about 50/50.
I am in the 75 % paint/25% thinner area.
I have just started using the Tamiya lawyer thinner.
I have also used Home Depot type lawyer thinner with it to hood success.
Iām all in favor of lawyer thinnerā¦
Autocorrect harumph 
Lol hate when that happens
For Vallejo Model Air, their Flow Improver makes wonders. A completely difference experience since I am using it, not as easy as Tamiya but usable enough.
Iāve tried the Flow Improver with no success. Iāve thinned it, thickened it, put a tiny nut in the bottle to shake up the pigment, used thinner and it still causes problems for me. I would love any help to make the 30+ bottles of Vallejo model air work since itās just sitting on my bench while I look at it with disdain!
Thanks!
I use an AZTEK and had problems with Model Air clogging the tip. Used their thinner, retarder, flow improver and couldnāt solve the problem. At AMPS Nats. one year I talked to one of the guys giving the demo and told him my problem. He suggested that instead of using their thinner I should use their airbrush cleaner instead. Gave me a small bottle to try. So using the airbrush cleaner and the flow improver my problem has been solved.
The thinning changes by much according to the desired finish. A matt finish on a tank is forgiving about the āorange skinā effect and the rate 50/50 seems acceptable. A plane with a glossy finish requires much more thinner and the use of some flow improver, maybe the Gunze levelling thinner, and consequently more layers.
I have been doing some tests with different thinners, specifically Tamiya and Mr. Color. The only issue I have using these is that I end up with a gloss finish.
I am assuming if I use Tamiyaās regular thinner, it will spray flat.
I am now using AK Real Colors almost exclusively, for all the colors they have and how remarkably they shoot. I use Tamiya on the odd occasion Tamiya has a color ( like Dark Iron) that AK RC doesnāt. I thin both 50/50 with Klean Strip Lacquer Thinner, $19.99 a gallon at Home Depot. I shoot it at 15 PSI and it never goes wrong. Shoots smooth as silk and never messes up. Gives me a beautiful, smooth flat finish thatās hard as nails and ultra thin. As it dries it sucks down to the surface and dries to a tight skin even if I put it on a little heavy in spots. Never any tip dry or clogging, ever. Even if I have to hang up the airbrush for 5 minutes to put more parts in the spray booth, a second of spraying wide open brings the airbrush back to normal and most times I donāt even have to do that. Clean up is a breeze. Shoot one cup of thinner between colors, no tear down needed. At the end of the airbrush session shoot 2 cups of thinner into the spray out pot, tear down and clean with lacquer thinner, ābore brushesā, and Q-Tips. 5 minutes tops and my airbrush is reassembled and squeaky clean. Iāll go back to my trusty and reliable Lifecolor acrylics for specific colors and special effects but thatās it - AK Interactive Real Colors, Tamiya, and Lifecolor are my trusted stable. All others have their problems and defects and go in the bin.