How do they make black paint?

Factual Questions
1

…or any other really dark color for that matter. Since you have to start with a white base, it would seem that the best you could do is some shade of gray.

2

2 years ago an Ace Hardware paint dept. rep came in to talk to the boss and I over heard him say black paint has a black base. Red paints have red bases, and yellow paints have yellow bases. And now we stock different bases for certain colors. But we don’t have black bases–not very high in demand

3

“Paint” ain’t white - unless white pigment has been added.

4

You don’t have to start paint with a white base. You can make black paint with just resin and carbon black, and use transparent filler pigments if you want a filler.

5

History of Pigments

6

The blackest black pigment I’ve ever run across is iron oxide. I’ve used it in makeup and tattoo inks, and I’ve never seen anything better. I don’t know whether they use it in paint, though. Iron oxide can be used to make a wide variety of shades: black, brown, red, umber, yellow. The yellow and red pigments are muted “rusty” versions, for the most part, but they are extremely stable and non-toxic. The different iron oxide pigments are characterized by their particle size.

White paint contains titanium dioxide (or zinc oxide, if it’s cheap). While this improves its cover, and brightens blends made with it, it’s not suitable for black paint and it’s not used. The base for black paint is just the paint base: colorless solvents and resins, mostly.

7

One chemical often used in paint, ink, toner, for coloring tires, and for numerous other uses, is carbon black, technically known as amorphous carbon. It’s formed when a material containing carbon is burned without enough oxygen to fully burn. The leftover residue is a fine, black powder.

The stuff is a mess and a half, too. Ever seen copier toner? That’s about what it looks like.

I work for a company that ships 10-20,000 pounds of carbon black every day. It’s so fine that it seeps through the bags meant to hold it, and, given enough time, will deposit a black, hard-to-wash-off residue on everything in the vicinity.

8

They do put iron oxide in paint. A lot of steel primers have red iron oxide in them because it inhibits corrosion. It makes an ugly color, but it doesn’t matter for a bridge primer. When I was working in the highway department paint lab we were playing around with putting yellow iron oxide in the yellow road paint because we had had to take the lead chromate out of it and the organic pigments we were using were pretty transparent, so we were putting titanium in there for opacity, which caused the yellow stripes to look too white at night. The yellow iron oxide made the paint a nasty brown color in the daytime, but it was a really good yellow color at night. I don’t know if or how they ever solved that problem.

All the black paint I ever worked with, which wasn’t much, just had carbon black in it for color, but we were always doing almost industrial-type stuff where the appearance wasn’t the most important thing.

9

There are two iron oxides :

1> Ferrite (Fe2O3) - Red or Reddish Brown
2> Magnetite (Fe3O4) - Black

10

True, native magnetite is black, and is sometimes used for pigment, but the pigment called “iron oxide black” is ferrite. (Magnetite, by the way, is a mixture of Ferric Oxide (Fe[sub]2[/sub]O[sub]3[/sub]) and Ferrous Oxide (FeO).

11

Thanks for everyone’s responses, but I don’t think we’ve got the answer yet. I was at Home Depot yesterday and I asked about their “dark tint” base, the stuff they use to make their dark colors. It is an off-white. So somehow they can take a gallon of off-white base paint, add a relatively small amout of pigment and make black - or at least near black. It must have something to do with the way the pigment molecules surround the other molecules… or something. I dunno.

12

Sitting in a bucket, the stuff i off-white. If you paint it on the wall without having the colors mixed in, I think you will find that it dries clear (or maybe a little hazy).

13

We do have the answer. It’s what I posted below. Any latex paint base is going to start out looking white or off-white, but that doesn’t mean it won’t dry clear.

What they’re doing is what Nametag said. They have a paint base with latex (which is always called latex even though it’s usually an emulsion of some other polymer like acrylic resin), water, additives and a clear pigment like talc or CaCO[sub]3[/sub]. This stuff will look sort of off-white when it’s a liquid, but will dry fairly transparent and colorless because opacity (hiding power) comes from the difference between the refractive index of the pigment and the refractive index of the medium it’s dispersed in. The refractive index of talc or silica or CaCO[sub]3[/sub] is close enough to that of dry latex for it to make a fairly transparent film, but far enough from the refractive index of water to make the wet paint opaque. (Wet latex by itself is also white and opaque, of course.)

If your paint base only has transparent filler pigments in it, they may look white when it’s wet, but they “disappear” when it’s dry and don’t affect the color noticeably. So if you put in dark tint colors, you’ll get dark paint from something that started out looking white.