Here's a Poser

I am using Tamiya thinner only with gloss paint and alcohol for the flat colors

They aren't giggling Ross, The're having a good old belly laugh .

Regards,  Rick

rjkplasticmod

I stirred it in the bottle & again after decanting & adding thinner.  I guess it's possible that  I didn't stir it enough, but the same bottle was used about a week ago & gave dead flat results.

Regards,  Rick

And the Paint Gremlins are giggling at you…

(Oh, they exist. Trust me. I'm an expert in these matters…)

Good suggestion Mike.  I'm getting old & feeble, so maybe my manual stirrer doesn't have enough ooomph anymore .

Regards,  Rick

That is odd Rick and I can't add anymore than these gentlemen have already said.

This is why I always use my paint mixer every time I paint as it mixes more completely than anything I have ever tried.

I stirred it in the bottle & again after decanting & adding thinner.  I guess it's possible that  I didn't stir it enough, but the same bottle was used about a week ago & gave dead flat results.

Regards,  Rick

Different colors of paint within the same brand may use different flatting pigments, some of which settle faster in the jar, others of which tend to plate out parallel to the coating surface. The cause of both is almost always incomplete mixing, sometimes combined with too much reduction (thinner). In Rick's case, the latter was not a factor, based on his reported thinning ratio.

Low relative humidity can also play a rather peculiar role. Many flat pigments, especially those specifically for making a paint flat, have an electrostatic nature—the charge distribution on their surfaces is not uniform. When they are aerosolized by spraying, in a dry environment, static charge can cause them to align peculiarly with respect to the paint surface, especially with thinly applied layers or with a highly volatile solvent. Most often, this produces a glossier surface than would normally be obtained, but I've also seen it produce a nearly "flocked" surface texture.

That, or Rick just wasn't holding his mouth right………

Wow, I've never had that happen before. Tamiya's Flat are about as flat as paint can get. I've had their gloss go flat due to too much alcohol, but I've never seen their flats go gloss. Are you SURE you stirred it well? Their flattening agents settle out pretty fast.

i dont know why maybe it is just a coincidence but my tamiya khaki always comes out glossy also..... weird

I have had similar results with Tamiya paints over the 20 years I have been using them. The usual cause is not being stirred well enough. the older the paint, the more likely this is to happen in m y experience. With Tamiya paints, shaken and stirred, or stirred thoroughly with a stick.