Grout Colorant: How to Change or Restore Grout Color Without Regrouting

Grout colorant (also sold as color seal or grout stain) is a pigmented coating brushed onto cement grout to give it a new, uniform color and seal it in one step. It works well on sound, clean grout with glazed tile, and is a fraction of the work of regrouting. It does not fix cracked, crumbling or recessed grout.

How grout colorant works

Most grout colorants are water-based acrylic, urethane or epoxy-modified resin coatings loaded with pigment. Brushed onto the joint, the resin wets into the surface pores of the grout and cures into a thin film that is anchored in the cement surface. Because the film carries the color, the original grout color no longer shows, and because it is continuous, it blocks liquids the way a membrane sealer does. For how this compares with invisible penetrating sealers, see penetrating vs membrane sealer.

That film behavior drives every rule of colorant work. It needs a clean, open surface to grip. It must stay off surfaces that would also grip it. It wears where traffic is heaviest. And when it is time to remove it, it behaves like a coating, needing a stripper rather than a cleaner.

When colorant is the right fix, and when it is not

If you are unsure whether the grout is worth saving, repair or replace grout walks through the decision.

Choosing the color

Colorant can make grout lighter or darker, but the two directions behave differently:

• Darker or same tone: usually one coat hides the old color. Wear shows less, because a light base under a worn spot reads as a small highlight rather than a dark blotch.
• Much lighter (for example charcoal to white): usually needs two coats for full hide. In traffic lanes, wear eventually lets the darker base show through as a shadow, so expect touch-ups.
• Mid-tones: warm grays, greiges and taupes hide everyday soil best on floors. The grout color guide covers how grout color reads against different tiles, and the grout color visualizer lets you preview options.

Colorant manufacturers often match the color names of major grout lines, which helps when coloring only part of an installation to match existing grout (see matching existing grout color). Wet and dry samples can differ; brush a swatch onto a scrap or hidden joint and let it cure before deciding.

Which tiles can colorant stain?

Colorant should only end up on grout. How easily it comes off the tile decides whether a job is a quick wipe or a disaster.

Tools and materials

• Grout colorant in the chosen color (check coverage in linear feet on the label)
• Prep cleaner recommended by the colorant maker, or a neutral cleaner followed by a mild grout prep product where allowed
• Stiff nylon grout brush, small stiff artist or toothbrush-style applicator brush, fine liner brush for narrow joints
• Damp sponges or microfiber cloths and a bucket of clean water; nylon non-scratch scrub pad
• Painter's tape for porous or textured tile edges and adjacent surfaces
• Nitrile gloves, kneepads, good lighting (a work light at a low angle shows missed spots)

Step-by-step: applying grout colorant

1. Confirm the grout is ready. New cement grout must be cured per its TDS before coloring; colorant makers commonly call for at least 48 to 72 hours, and some prefer longer. Existing grout must be sound: scratch a joint with a key, and if it powders or gouges easily, repair or regrout first. Fill cracks and voids with matching grout and let that cure too.
2. Check for old sealer. Drop water on several joints. If it beads, a sealer is present and may block adhesion. Remove it with the method the colorant maker specifies, often a sealer stripper or an alkaline cleaner and scrub, then retest. If an old membrane coating or colorant is present, strip it; see how to remove grout sealer.
3. Deep clean and prep the joints. Scrub with the prep cleaner and a stiff brush to remove soap film, grease and soil. Many colorant systems use a mildly acidic prep cleaner to lightly open cement grout; never use acid prep on marble, limestone or travertine. Rinse at least twice with clean water so no cleaner residue remains. See how to clean grout for heavy soil.
4. Let the grout dry fully. Allow 24 hours or more, longer in showers and on slab floors. Colorant over damp grout can blister, whiten or fail to bond. The joint should be uniformly light with no darker damp areas.
5. Mask and test. Tape porous tile edges, trim and adjacent surfaces. Stir the colorant thoroughly (pigment settles), and run a test joint in a hidden area if you have not already.
6. Apply a thin, even coat to the joints. Work about 5 to 10 sq ft at a time, or a few feet of joint on walls. Brush colorant into the joint, working it into the texture of sanded grout, keeping a thin layer. Aim to stay on the grout but do not panic about small overlaps on glazed tile. Thin coats cure harder and look more natural than heavy ones.
7. Clean the tile faces on schedule. Within the window on the label, often a few minutes for porous or matte tile and longer for glossy glazes, wipe overlap from the tile with a damp sponge or cloth, rinsing it often. Use light pressure along the joint edge so you do not pull colorant out of the joint. Some products instead direct you to let overlap dry and remove it later with a damp nylon pad; follow the specific TDS.
8. Inspect with low-angle light. Look for missed spots, thin areas and pinholes before moving on, especially at joint intersections and along wall corners. Touch up while the section is still workable.
9. Apply a second coat if needed. When changing to a much lighter color, or where the first coat looks translucent, apply a second thin coat after the recoat time on the label, commonly 1 to 2 hours. Clean the tile again on schedule.
10. Let it cure before use. Typical guidance is light foot traffic after about 24 hours, no water or cleaning for 72 hours, and full hardness and stain resistance after several days. Keep showers out of service for the full time on the label. Remove tape once the surface is dry to the touch, pulling at a low angle.
11. Remove residue and maintain. After cure, check tile faces for a thin pigment haze and remove it with the maker's recommended method, often a nylon pad and water or a mild cleaner. Clean routinely with neutral pH products only; strong acids and harsh alkaline cleaners shorten colorant life.

Typical working and cure times

Common colorant failures and causes

Peeling or flaking

Almost always adhesion: sealer or soap film left on the grout, grout still damp, or colorant applied too thick. Peeling patches must be scraped back to sound material, cleaned and recoated; on large areas, strip and redo.

Patchy, uneven color

Thin coverage over a contrasting base, unstirred pigment, or uneven absorption from partial old sealer. A second thin coat usually solves the first two; the third requires stripping the sealer.

Haze or tint on the tile

Overlap left too long or porous tile. Fresh residue comes off with a damp nylon pad; cured residue may need the colorant maker's remover. Test any remover on a hidden tile.

Wear in traffic lanes

Expected over time, and different from fading grout caused by pigment loss in the grout itself. Wear comes sooner with light colors over dark grout and with grit and harsh cleaners. Clean, let dry and touch up the worn joints per the maker's instructions.

Whitening or blistering in showers

Water got behind the film, from damp grout at application or from water moving through the wall. Persistent problems point to a moisture issue that colorant cannot solve.