When airbrushing, I always dilute Tamiya acrylics with a lacquer thinner at 1:1, have never had an issue. Today I tried the same with their metallic colors, such as XF-56 Metallic Grey and X-11 Chrome Silver, and my airbrush became quickly clogged. I still managed to finish the job (the paint would go through in an on-and-off kind of fashion), but I didn’t expect something like this to happen. [:O]
I am using an Iwata HP-C (0.3mm nozzle).
Any suggestions? Thanks!
Try experimenting with different ratios
Sounds like junk in the nozzle causing intermittent flow. If anything the paint should have gone thru without any issues.
Funny. I just posted something similar on a recent thread. I shoot tamiya chrome silver, flat aluminum, and metallic grey but with X20A all the time with no problem. I have the same airbrush but use 2:1 paint to thinner.
So, your mix is actually thicker than mine? I will try X20A instead of lacquer, thanks!
I don’t think so. Will try different ratios, as others suggested.
Use x20-a acrylic thinner, not lacquer thinner. Should be fine.
I may be on the right track, may not be junk but the actual metallic paint particles separating and making it hard to go thru the fine tip as described in this old thread:
http://cs.finescale.com/fsm/tools_techniques_and_reference_materials/f/18/t/97485.aspx
No it’s the right track, that’s what happens with metallic particles, they drop out of suspention. The more you thin, the quicker they settle. But this can be mitigated greatly in a couple of ways. Of course less thinning becomes the first thought, which doesn’t stop the settling but does slow it way down maybe even to where you can complete a coat of paint… But suppose the look you want is with more thinner and lacquer thinner at that ? Well you have to keep the cup agitated and those particles in suspension, this is simply by swirling the cup between passes or every couple of passes. We used to do this in 1/1 actually on the last couple of coats which were extra thinned and I also do it with MM Metalizer paints , what I have left of those that is.
It’s not that there is magic in X20a but you tend to need less to have the paint still flow, so ya X20a will help simply because the paint isn’t thinned out to the same degree ( and of course it is a good thinner). That said, a lot of folks like to thin Tamiya 1-1 with lacquer thinner but it actually goes on quite well thinned 3-2 ( 3 parts paint, 2 parts thinner) or somplace between there and just short of 1-1. And that too may well help keep those metallic flecks in suspension. Still swirl the cup though.
That’s my short bit on the subject. We sprayed a lot of 1-1 metallics. Some colors were naturally thinner than others in both lacquer and enamels. But some of the flow control is in the thinner used. So ya we ran into this even in 1/1. I remember light green metallic Centari Acrylic Enamel being very prone to this where you wanted some medium dry reducer in there for flow and proper flash off but really the viscosity of the paint came very close to ready to spray. And you had to be careful on certain silvers too. Silver was funny, some silvers were like glop and needed a lot of thinner, others quite thin already. And by the way in learning to paint we thinned paint by viscosity cup, ratios weren’t a thing. You thinned till it flowed through the X amount of cc cup in X amount of time. Once you learned proper viscosity and how that flowed off a stirring stick you had it memorized and didn’t need the cup after several uses. Then from there different techniques of spraying were just minor adjustment. I remember the cup, was called a Ford Viscosity Cup. It was a fixed quantity of paint but different types of paints had different timings for the paint to flow through. Actually here’s a video:
After you thin the paint put in one drop of Tamiya Paint Retarder and it should improve the flow. Tamiya metallics drove me nuts until I started using it.
I have had troubles with Alclad with any color if I work too long. I have to stop and do a temporary cleaning and return to airbrushing. I have trouble finding the retarder at LHS. When I do find some I will buy several bottles. In the meantime I willl just realize if it is a big job ahead I may have to clean before I finish the job.
Well, I just tried using X20A (acrylic thinner), instead of the lacquer thinner, and I got the same results. 
Basically, I have to pump the needle back and forth all the time which causes the paint to come out in spits, otherwise it does not spray at all.
I don’t have the retarder yet handy, unfortunately.
The problem is the airbush then. Either not as clean as you think or the nozzle and needle are too small.
This is odd, indeed. Would not imagine that 0.3mm is too narrow. I wonder what nozzles other people are using.
I haven’t opined becuase I’ve never used Tamiya acylic metallics, but becuase you asked, here’s my opinion.
Were it me, I’d be suspicious indeed of the .3mm needle with any acrylic metallic.
I’m not a big fan of small needles in our hobby airbrushes. Two days after I bought my first double action airbrush (Iwata HP-C, same as you) I ran to HobbyLobby to buy a .5mm needle/nozzle set to replace the .35mm which was giving me catfits. The .35 hasn’t gone back in since. My Harder & Steenbeck has the .4mm installed, and the .2mm sits patiently waiting for me to discover my “special purpose” for it. I’m in the process of switching over to some lacquers, so maybe that will be it? We’ll see.
But that’s just my opinion of needle sizes and from my experience it’s not a very popular one. Folks swear by their tiny needles and I figure one of these days I’ll probably find out they were right after all.
In summary, I’m definitely not saying your needle is too small. Just suggesting that it might be.
Thank you, Greg. That may indeed be the case. Besides that HP-C, I only have a Custom Micron B (0.18mm) which, most likley, is not going to help in this situation.
I have some Citadel metallics, which seem to have finer particles, at least by the look of them, and a bottle of AK Xtreme Metal. Haven’t tried spraying either of them yet, but may have better luck with them, who knows.
Just shot Tamiya gunmetal on tank tracks heavily thinned with x20A in my .35 tipped AB set at 20 PSI and had no issues.
Maybe not, in this case, but that’s sure a cool airbrush. [Y]
There ya go. Real life experience. Ernie said 'heavily thinned with x20A", maybe you could try more thinner.
OT but: Flory Models loves his .2 in an H&S for lacquer paints. He keeps it set up that way just for lacquers. He has two, one for enamels and acrylic, the other for lacquer. He keeps the .4 on the enamel/acrylic brush.
I’ve always shot MM Metalizers which are lacquer through my Badger .25. and years ago I shot Floquil lacquers through that same .25. Really that .25 is my favorite nozzle, it just does things right, the atomization is really fine and yet with thin paints I can back away and still get a decent swath of paint down. Lacquer is pretty thin stuff, you might come to like those finer needles when using them. Just sayin.
That said I do use other needles too.