Why Do Some Paint Labels Say 'Must Be Tinted'?

Next time you're browsing the paint section for a DIY home project, be careful not to mistake paint labeled "must be tinted" for a paint or primer that works as-is. Unlike pre-colored paint, paint with this label is an incomplete formula. It might appear to be a perfectly normal white paint base after you've mixed the paint in the can (albeit a bit on the low side). But some essential ingredients are missing from the product that, when used, can deliver an outcome that's less than ideal — if not downright disastrous.

Each paint company uses its own proprietary tinting formula, adding a precise combination of solvents, binders, and pigments to every paint can. If the paint is labeled "must be tinted," once you've picked out a paint hue for your project, your local home store will follow precise directions for adding pigments to achieve the exact color formula you're looking for. When you find pre-colored paint that doesn't come with the "must be tinted" label, that just means the tint has already been added to the base formula.

However, if you don't get those pigments added to your "must be tinted" can, that paint will likely be much thinner or more translucent and milky than it would be after the pigments are added. This unfinished paint functions more like a varnish than a neutral base paint without a "must be tinted" label. Depending on the formula, an untinted paint base may even have trouble sticking to a surface without the right combination of binders and pigments.

Whether you've stumbled across a can labeled "must be tinted" somewhere in your garage's mysterious paint corner or you've accidentally taken off from the home improvement store without getting your paint mixed, you're certainly not the first DIYer to make this mistake. "This happens all the time at home centers where they have the paint bases out where customers can get to it, take it not realizing it's a base, not drop it off at the counter to have it shook, and then not question why the gallon looks like it's a pint low," shared one Lowe's employee on Reddit.

If you recently purchased such paint, first try heading back up to the home improvement store where you bought it. Employees on Reddit's r/paint tend to agree that the customer service counter should be fairly understanding since a good employee would have stopped you from buying it without making sure you knew what you had. If you can't return or tint your paint for some reason, you can simply buy a new, appropriately tinted can of paint. Or, if you've chosen a shade of white paint, one user on Stack Exchange's DIY Home Improvement page suggests trying to tint it yourself. They advise mixing in pure titanium oxide pigment, which should give you more coverage and opacity than the untinted base. 

In the case that you've already used some of the paint, the store may or may not be able to tint what's left. One option is to pick up a smaller can of the same paint, as well as an empty can of the same size. Determine how full the new can is, measure out this same precise amount of the original pre-tinted paint into the empty can, and then ask the paint mixer to mix it accordingly. Good luck!