Alclad responded to the mottling issue: please see below!
There's an update a few posts down....
I'm nearly finished with some test shots of Alclad II and Testors paints for use in a demonstration at the local IMPS chapter club meeting in a couple of weeks.
The main purpose was to see what effect, if any, different base colors have on metallic paints. Would the variations be significant enough to represent different panels on a bare metal aircraft? We know that gloss black affects Alclad Chrome and Polished Aluminum, but what about other Alclad paints? And how about ModelMaster Metalizers?
So off I went. Part 1 was to paint a series of vertical stripes in varying colors, followed by horizontal stripes of the metallics. I used a 12"x24" sheet of white styrene, plus a length of 1-1/4" PVC pipe, to see the effect on a curved surface. I left thin spaces showing the base colors to make it easier to determine which undercoat had any effect on a given color.
The 9 color Stripes: Mr. Surfacer 1000, Alclad Gloss Black undercoat, Testors enamel White, Blue, Green, Yellow, Xtracolor International Orange, Testors enamel Red and Brown.
The 24 metallics (top to bottom): Alclad II Chrome, Polished Aluminum, white Aluminum, Duraluminum, Aluminum, Dark Aluminum, Semi-matte Aluminum, Dull Aluminum, Airframe Aluminum, Magnesium, Stainless Steel, Steel, Titanium Gold, Pale Burnt Metal and Copper; Testors ModelMaster Buffing Metalizer Stainless Steel, Titanium, Exhaust, Brunt Metal; Non-Buffing Metalizer Steel and Brass; ModelMaster Enamel Silver Chrome and Aluminum.
Time was short, so I wasn't able to let the base coats properly cure. I painted the metallics in three sessions, every third stripe. The first two shots I did not put anything over the base coats, and the Alclad crazed the green and the orange. I shot Future over the remaining undercoat strips as a barrier, and the last set of metallics did not attack the undercoats.
The Alclad Stainless Steel left a mottled pigmentation, though the surface is smooth. I'll need to do some more test shots before I trust it on a model. I got a slight run, and it was the only part with smooth pigmentation. The color will look more like the real thing than the ModelMaster Stainless Steel, if the uneven pigmentation can be gotten under control.
Some of the colors are more transparent than others. The Alclad Titanium Gold and Pale Burnt Metal showed the greatest differences among undecoat colors. Most of the rest had very subtle differences, if any. Airframe Aluminum showed enough subtle variations that it might serve to differentiate panels on a '50S jet model without looking like a checkerboard. The ModelMaster Brass also showed a marked effect from the undercoat. The effects of glossy Yellow undercoat seemed more pronounced that most of the other colors, except black or white.
Dust is a huge problem for me right now; Phoenix hasn't had any rain for some 130 days, and the particulates are everywhere. It's amusing to read all these guys complaining about humidity wrecking their paint jobs. We have about 8% here, and I must run an inexpensive room humidifier next to my makeshift paint booth. That aside, the most sigificant difference had to do with the glossiness of the undercoat. The darker colors, blue and brown, had about the same result as the gloss black. Apparently any dark glossy undercoat will do, but the surface has to be flawlessly smooth, and dust free. The curved surface showed greater effects when viewed from an angle rather than square on.
The second part was to make some test strips on 3/4" PVC pipe. Half of each pipe was painted Alclad Glossy Black undercoat vertically; the other half Mr. Surfacer. One pipe was painted in adjacent strips of the same Alclad paints listed above, while the shorter pipe had the same Testors paints as above.
All that remains is to make and apply decal labels for the metallics. If anyone is interested, I'll try to take some detailed shots under daylight and post them later. Anyway, I learned a lot, got some more practice applying metallic paints, and now I have a sampler for selecting colors.
"You can't have everything--where would you put it?"