First of all, I spray in my garage and wear a full mask. I would not recommend this indoors. I reduced Tamiya acryls, with MEK(5:1). This is the result:
I will experiment, with other lacquers and some enamels this afternoon.

Why? Seems to me there are better alternatives available-- MEK probably isn't the best for much of anything, unless you are trying to get a real "bite" on kit plastic for some reason.
VR, Russ

MEK is some pretty nasty stuff. I'd only use it for industrial applications and not models. Wear a mask and have some serious ventilation going on, if you decide to stick with it.

Taking a stab here as its been 45 years since freshman chemistry.
MEK=methylethyykeytone? Really nasty stuff. Will make you null and void. Wouldn't mess with the stuff unless there were no other alternatives.

MEK's toxicity was discussed at some length, on FaceBook. A chemical engineer said that the minor use of it, in the hobby was quite tolerable. Still, I wear a full mask and gloves.
I have reduced Tamiya acryls, with about everything I can think of and MEK behaves much better.

Well, it's used primarily as an additive for adhesives, and to thin different types of lacquers and acrylic lacquers (hence the reason it probably works well with Tamiya paints which are acrylic lacquers) for brush work. In small quantities, it's probably OK, but frankly, aerosolizing it in an airbrush is probably not the wisest idea, especially in an enclosed space (and a garage is an enclosed space unless the doors are open). It should only be used with an approved MSA rated mask, designed for toxic substances, and with at least 5 mil rated rubber gloves, which are what's commonly found in laboratories. Frankly, I wouldn't use it in an airbrush, and I'm an old crusty Chemical Officer. Mek is also a percutaneous contact hazard (absorbed through the skin) if you start having any neurological issues, I'd see a doctor right away. "On line chemistry" is not the best source for information-- but you can always read the CDS on the side of the can.
VR, Russ

P.S.-- unless you are using a full face mask, remember that MEK is an eye irritant. You didn't say what type of respirator you were using, but most commercial rated masks for aerosol painting are not full face masks.

Just...why?
Even if you are trying to find an alternative to the more expensive name brand paint thinners (Tamiya, Testor’s, etc) there are much better thinners available. I can’t see any reason to use this stuff for the possibly minute benefit you think you will get.

I was an aircraft tech in the airforce and this stuff used to be available for cleaning parts, but I think it is not even issued anymore. If it is you should use full PPE.

My father was a chemist, in the EOD. He is aware of the dangers and recommends full safety gear and not spraying indoors. By "indoors" I mean in an enclosed space.

So how does any qualification he had transfer to you. Our indeed any common sense for that matter by the sounds of it.

Heed the warnings.

Plenty of much safer alternatives available or maybe you're the kind of guy who lights his barbeque with aviation fuel....

Quite simple. I asked him. As for common sense, he spent eight years working with chemical weapons. How many years did you spend working with chemical weapons?

MEK
Isn't that the same stuff in some of those liquid glues ?
I just use regular Laquer thinner, for all the paints including Tamiyas.
It works fine ,
Regards.
Donald

I thought this was a modelling forum for discussing modelling matters. It may be that sarin ( for example) is an excellent thinner for acrylic or indeed any other type of paint and that you or your father can handle it safely but I’m still unclear on why, when less hazardous alternatives are available, one might consider using it for thinning paint.

While I use MEK in small quantities as a cement, I’m not sure that the risk/reward balance for me would incline me to spraying the stuff so that I could ingest it more easily, or to have to wear a hazmat suit to avoid doing so.

If you want to take all those precautions and spray the stuff, that’s fine. I’m just not sure most of us would be emulating you.

Thanks for the info.. I have some of the Tamiya enamels and some MPK... might give em a go. I can not stand how they paint now, nor how the acrylics spray. The question is does MEK or MPK help with the normal issues with the acrylics spraying or the lack of adhesion. Only one way to find out...

The evaporation rate of MEK is so high, that I cannot see the
benefit of using it as a thinner.

Imagine the speed at which one would experience nozzle clogs!

and of course the hazards of atomizing it without proper
protective equipment.

Cheers,

Matt buddy, I think I have your dad's eight years beat-- I spent 25 years as a Chemical officer (and five years as a tank officer). I spent three years of my career working at Dugway Proving Ground, where I worked with Material Safety and Chemical Safety Data Sheets and Chemical Surety Operations almost daily. I spent another three years in R & D subject areas as a joint duty officer working CBRN subjects for the Navy and Marine Corps. This was followed up with duty on Johnston Island, and in Chemical Weapons recovery in the Pacific. MEK is a puny hazard when compared to chemical weapons I agree, but it doesnt make it any less dangerous if not handled carefully. All the same, few of us who worked in the Chemical field would deliberately take a risk of exposure with any chemical agent, even MEK, if we didn't have to. Although not a chemical exposure story, it reminds me of an incident when recovering WWII Mustard Gas weapons in the Solomon Islands. We had a LTC who refused to take his malaria prophylaxis based on his "extensive" experience as a Chemical and Biological Defense Officer. He used the apparent absence of malaria in the native population near the weapons site as proof there was no malaria threat present. But two years later, after being re-assigned to the Pentagon, he came down with latent malaria. While I was working on the weapons site (taking full malarial prophylaxis by the way), I asked the local Australian plantation manager about an apparent lack of malaria on the Island-- he joked, and said "oh malaria is no big deal, we all have it, I have a bout of it every two or three years mate, I just medicate with gin and tonic and I'm back to normal in a week or so!" Just because someone told you there is no hazard doesn't mean there isn't one lurking. MEK is a toxic solvent, and really not worth the risk of aerosolizing it when there are better alternatives. Each to his own though-- I wouldn't do it, but if you think you can protect yourself, it's your business. But as seniors in our hobby, we have an obligation to inform others sharing our hobby about the associated risks.
Very Respectfully,
Russ

It's your common sense I was questioning not your Fathers.
But then again you just come out with this crap to try to make a impression on the forum. You've been doing it for years. Thankfully 99% of the posts on this thread are warning against the ridiculous use of MEK as a thinner, which hopefully will mean most will be put off your stupid suggestion and not risk their health or anyone close by taking up this ridiculous suggestion.

Let me share a little something for everyone.When I was growing up there was a paint and body shop across the street from my house.One of the guys that worked there his entire life NEVER wore any kind of protection when painting the vehicles.Long short,years of breathing paint fumes just "fried" his brain.

I appreciate the concern and apologize for getting aggressive. I won't be using this regularly or often. Possibly, only when I need the finest spray pattern I can achieve. Again, if I notice any effects, I will put it away for good.

I don't know what you mean by the finest spray pattern but I have been using Tamiya "acrylics" thinned with their lacquer thinner(yellow cap)for years. I do all my paint work, including intricate camo patterns freehand using an Aztec airbrush and have never had a problem getting the results I want. Fine airbrush work really depends mostly on two related things, thin paint and working at low pressure. This requires working slowly and close to the surface and takes considerably more time than spraying at a more conventional pressure and distance. If done correctly you can almost eliminate all overspray. Any that remains disappears with the weathering process. Like everything else with an airbrush it takes some practice finding the correct thinning ratio and air pressure you are comfortable with.

For some reason, my brushes spatter. I used to be able to achieve hairline spray patterns, using MLT. I will be getting a new brush, soon and see if the ones I have need a "tune-up". They are about 9 years old.