What does it mean "yellow or red, blue or green, black or white?" Looks like all these colors.

It is all those colors. And more.

Can I paint metal with it?

I personally have used it to paint designs on plastic rubber mud flaps without a clear coat and it lasted for 5 years, it did fade a little , I sold the vehicle so I am not sure how much longer it lasted. Also used it to paint name on metal mailboxes and hanging signs. It faded but has lasted about 20years. I did not use any primer and didnt prep the surface.

does this set come with paint thinner

Yes it does but you may want to consider getting a larger container to fill it up when you run out. You would be surprised how fast paint thinner disappears especially when using several different colors and brushes that are different sizes that use more paint and paint thinner to keep clean.

Is the enamel paint oil-based or water-based?

Well Testors is an enamel, it is definitely not water based! I do not think it is oil based either. I think it's solvent is an alcohol. For anyone that asks, Testors was the standard paint for model makers for about 50 years, now the Acrylics are taking over. The Acrylics are definitely water based. A cup of water is all that is needed for a brush cleaner.Another BTW, in the Testors Promotional Kit shown ... the bottle of "paint thinner" is way tooooo small, buy an additional bottle about 5 times bigger. This thinner/solvent is needed as a brush cleaner. I keep a spare bottle to put the "used" cleaner in and I keep it as a "sanding sealer" rather than dumping it down the drain.Joe

ASIN	B00005C2KF
Age Range Description	Adult
Brand	Testors
Brand Name	Testors
Color	Multicolor
Color Code	000000
Container Type	Bottle
Coverage	see package
Customer Reviews	4.7 out of 5 stars 6,440 Reviews
Finish Type	Gloss
Global Trade Identification Number	00075611914602
Included Components	Paint Set
Indoor Outdoor Usage	Indoor
Is Waterproof	False
Item Form	Liquid
Item Type Name	Paint Kit
Item Volume	66 Milliliters
Item Weight	0.65 Pounds
Manufacturer	Testors Home
Model Name	Testors Enamel Paint Sets
Model Number	9146XT
Paint Type	Enamel
Part Number	9146XT
Size	1 count (Pack of 1)
Special Feature	Fast-Drying
Special Features	Fast-Drying
Specific Uses For Product	Interior
Surface Recommendation	Various
UPC	075611914602
Unit Count	1 Count
Warranty Description	Warranty.

9146XT Promotional Enamel Paint Set( Packaging may vary)

Details

Description

Specifications

Common Questions