How to Get a Color Match From a Paint Chip

Why this matters

"Just match the paint" is a sentence that sounds like a ten-minute errand and turns into a second trip, a quart of the wrong color and a patch that reads from across the room. A color match is not something the paint counter does to a chip; it is a short chain of decisions the tech makes before the chip ever leaves the house: whether a formula already exists, which piece of wall the color is taken from, and how the sample is judged. Get the chain right and the counter's job is easy. Get it wrong and the best scanner in the store faithfully reproduces the wrong thing.

The procedure for laying the paint on once you have it lives in its own card (see related: How to Touch Up Paint So the Patch Does Not Flash).

Step 1: Look for the formula before you cut anything

The most accurate match is the original formula, and it is often in the building. Ask the customer, then look: garage shelves, the basement, a utility closet, under the sink. Read the lid, not the side; the counter prints its label for the lid.

PAINT CAN LID LABEL (mock, fields typical of a
store-tinted can)

COLOR ....... HARBOR STONE      NO. 21-07
PRODUCT ..... INTERIOR ACRYLIC, LINE B
SHEEN ....... EGGSHELL        BASE ... 2
SIZE ........ 1 GAL     MIXED 03/18/2022
COLORANT          AMOUNT (machine units)
  WHITE           0 - 22
  YELLOW OXIDE    0 - 35
  RAW UMBER       0 - 11
  LAMP BLACK      0 - 03
TICKET 4471   STATION 2   ROOM: "HALL"

Every line matters, and techs routinely use one of them. The color name and number let any counter look the color up. The product line, sheen and base matter as much: the same color formula in a different line or a different base dries to a different look, because the resin and the base's own white content differ. The colorant lines are the exact recipe for that product and base, in the units that tinting system uses, which is why a formula is only exact when re-mixed in the same line. The room note, when someone wrote one, tells you which wall the can belongs to.

Check the can belongs to this wall. Four cans in a garage can be four rooms. Match the lid's room note, or brush a dab from the can on a scrap and compare it dried against the wall before trusting it. Photograph the lid label for the job file whether or not it turns out to be the right can.

Step 2: If there is no formula, take the color from the right piece of wall

The chip is the color sample the store will read, and it has to be the color the wall is now, not the color it was when it was painted. Paint fades and yellows with light and age, so a chip from a spot that has been hidden from light (behind a switch plate, inside a closet, under a mirror) gives the original color, which may no longer match the faded wall you are patching.

The best chip is the one you already cut out. If your work required an access cut, keep the piece of drywall you removed. It came from the exact wall, at the exact spot, with the exact exposure, and it is large and flat. Mark its face "keep" with a pencil on the back the moment it comes out, so nobody throws it in the debris bag.

If there is no cutout, take the chip from the edge of the area you are going to patch anyway, where the new paint will cover the scar. Make it at least the size of a coin, about 1 in across; smaller chips are hard for a scanner to read cleanly. Cut it with a sharp utility knife scored through the paint and lifted with the face paper or the plaster skin, rather than peeling paint, which curls and shows its underside. Pick a flat area: texture and its shadows can skew the reading.

Old paint is a lead question first. In a pre-1978 home or child-occupied facility, score and lift the chip with the surface misted with water rather than scraping or sanding, collect the debris on a damp wipe, and wash your hands before eating or smoking. A coin-size chip is far below the 6 sq ft per room minor-repair threshold of the federal lead renovation rule (40 CFR Part 745) for interior work on paid jobs, but the patch it is part of may not be, so count the whole disturbed area, not just the chip. Some states run their own authorized programs.

Step 3: Keep the chip clean, dry and flat

Put the chip face up in a paper envelope or between two pieces of clean card, label it with the job, room and wall, and keep it out of the sun and away from the truck's floor. A chip that picks up grease, dust or water reads as a different color; a chip that cracks loses the flat area the scanner needs. Do not tape over its face.

Step 4: Name the sheen yourself

A color scanner reads color. It does not reliably tell you sheen, and the counter will mix whatever sheen you ask for. Identify it at the wall: look at the surface with light raking across it and compare to a sheen sample card, or to a painted surface whose sheen you know. Flat, matte, eggshell, satin and semi-gloss are distinct enough to call with a little practice. Also note the product type if you can tell it, such as a water-borne acrylic wall paint or an alkyd enamel on trim, because a touch-up in the wrong type will not look or wear the same.

Step 5: Ask for a scan and a sample, not a gallon

At the counter, ask for the chip to be scanned (a spectrophotometer reads the color and the system proposes a formula) and for the smallest sample size they mix, in the product line and sheen you named. Buying a gallon before testing turns a cheap mistake into an expensive one.

Step 6: Test the sample dried, on the wall, in two lights

Paint the sample onto a sample board or a piece of scrap drywall about 12 in square, two coats, and let it dry for the label's recoat time at least and ideally overnight. Wet paint is not the color it will be: many colors shift noticeably as they dry. Then hold the board flat against the wall beside the patch area and look in daylight and again under the room's own lights.

The two lights matter because of metamerism: two paints made with different pigments can match under one light and differ under another. A board that matches at the window and turns greener under the room's lamps is a metameric match, and the counter can adjust the formula if you bring the board and the chip back.

Do not judge the sample by painting it straight onto the wall. If it is wrong, you now have a second wrong color on the wall to cover.

Step 7: Record the formula you used

Once the sample matches, write it into the job file and onto the new can's lid, because the next tech, or you in two years, will need it.

JOB FILE NOTE, finish match

Room/wall ... hallway, east wall
Source ...... chip from drywall cutout (no
              matching can found)
Sheen ....... eggshell, called at the wall
Scan ........ formula on new lid, LINE B,
              BASE 2, sample mixed 1st
Test 1 ...... board dried overnight: match
              in daylight, warmer under hall
              lamps; counter adjusted
Test 2 ...... board dried overnight: match
              in both lights
Final ....... formula from test 2 on lid +
              photo in job file

Worked example: two cans, one hallway

A plumber cuts an 8 x 8 in opening in a hallway wall to reach a leaking valve and is asked to leave the wall painted.

The formula search. The customer finds two cans in the garage. One lid reads "HALL", flat, in a product line; the other reads "BEDROOM 2", eggshell. The tech checks the hallway wall in raking light and calls it eggshell, not flat. That conflict means the "HALL" can is from an older paint job or a different hall, so the tech brushes a dab of each can on scrap and lets them dry while the repair goes on. Dried, neither matches the wall: the "HALL" can is noticeably lighter, and the "BEDROOM 2" can is a different color altogether.

The chip. The 8 x 8 in cutout went into the debris bag before the tech thought of it, but it is still on site, so it comes back out, is wiped dry and goes into an envelope. The house was built in 2004, so lead is not a question here.

The counter. The cutout is scanned, and the tech asks for a sample of the proposed formula in eggshell.

The tests. The first board, dried overnight, matches in daylight but reads warmer under the hallway's warm-white lamps. The tech brings the board and the cutout back; the counter adjusts the formula. The second board matches in both lights, and the tech records it as shown in the job note above, then buys a quart, which is plenty for a primed 8 x 8 in patch feathered out per the touch-up card.

What the shortcut would have cost. Using the "HALL" can because its label said hall would have put a lighter flat patch in an eggshell wall, which flashes on two counts at once and almost certainly becomes a whole-wall repaint.

What changes the method

• Exterior paint. Exterior paint chalks (its surface breaks down into a powder) and fades faster. Wipe the chalk off the chip area before cutting, and expect a faded wall to match a scan of itself better than any original formula.
• Stained or smoke-filmed walls. A kitchen or smoker's wall carries a residue that changes its color. Clean the area around the patch first, and take the chip from the cleaned surface.
• Trim and doors. Often a different product and sheen from the walls, often alkyd on older houses. Match each surface separately; do not assume trim is "the same white" as the ceiling.
• A wall that is already patchy from past touch-ups. There may be no single color to match. That is a whole-wall repaint conversation, not a chip.

References

• 40 CFR Part 745, Subpart E (EPA lead renovation rule), or the state-authorized program where one applies.
• Paint manufacturer product data sheets for sheen, recoat and dry times.
• See related: How to Touch Up Paint So the Patch Does Not Flash; Why Paint Touch-Ups Flash.
• See related: Why New Material Does Not Match Old Material; Plan the Restore Before You Remove the Finish.