Miller41’s question about thinning Model Master enamels prompted me to ask if any of you have had problems with MM enamels turning into a thick, useless gel? I have tossed several (7-8) bottles, some almost full, over the past few years that had become VERY thick and gel-like. NO kind of thinner could “bring 'em back” to useful life. My LHS guy said it sounded like a contamination problem. I had been using wooden toothpicks or bamboo skewers to stir the paint so maybe it was a reaction to those. My wife works in a dental office (lot’s of good modeling supplies there!) and she now supplies me with plastic mixing sticks. And, it does seem to have helped. I like the MM enamel but not as well as Humbrol. I have never had a similar problem with Humbrol enamels. BTW, I have Testor’s enamels in the 1/4 ounce bottles that were bought circa '65 or '66 that are STILL viable paint. Hehe, the tops of the lids say “.19 cents”. Pretty good investment, eh what?
I’ve had this happen as well with a few bottles as well, exactly as you described. Testors Technical guide explains that this is due in part to evaporating solvent from the paint. If the bottle is not screwed on reletively tight, solvent will continue to escape and cause the paint to gel. What I do to minimize this is to decant only as much paint from the bottle as I’ll need for the job and emmediately wipe the threads and cap the bottle…reletively tight. Testors also recommends turning the bottles upside-down to store paints, and it works! My Testors MM paints have lasted well over the advertised shelf life of 3 years following this routine.
I had to toss away a bunch of MM bottles because of this. Seems like MM doesn’t have very good storage life or the bottle does not seal very well. I’ve got 25 year old Pactra enamel still usable. I tend to think that the MM enamel formulation just doesn’t have good storage life. I tried to salvage some of the MM paints and thought I had saved a bottle after mixing it well with lacquer thinner. It looked smooth and so I started airbrushing a model with a Aztek airbrush. After a few minutes doing base coating paint won’t come out and I looked into the color cup and saw that the paint had clumped up again. Needless to say my airbrush nozzle was all gunked up. That was the straw that broke the camel’s back and I decided to switch airbrushes. I was not going to spend money getting another nozzle. (I went through like 3 clogged nozzles which couldn’t be cleaned without disassembly which can destory the nozzle.)