Diatomaceous Earth Care Guide — How to Keep a Stone Mat & Sink Tray Clean

Diatomaceous earth care, in plain English

Diatomite (sometimes called diatomaceous earth or stone) is fossilized algae pressed into a flat board. It's full of microscopic pores, which is why it pulls water out of a wet plate or a sink-side soap pump in seconds. Treat it like the porous stone it is and it lasts for years; treat it like plastic and it gets gunky in months.

Daily, almost no work

If you use the mat or tray to drain dishes, the surface dries itself between uses. You don't need to wipe it dry. The whole point of diatomite is that the moisture goes into the stone, not on top of it. Leave it alone, let air do the work.

If you spilled coffee, oil, soap residue, or anything pigmented onto it, dab the spill up immediately with a paper towel. Don't rub. Rubbing pushes the stain into the pores instead of lifting it off.

Weekly, if you cook or bathe a lot

1. Lift the mat or tray. Run it under warm water, both sides.
2. Use a soft sponge with a tiny drop of dish soap. Wipe in straight lines, not circles.
3. Rinse off all the soap thoroughly. Soap residue clogs the pores.
4. Stand it on its edge, against a backsplash or wall, to air-dry. Both sides need airflow.

The whole thing takes 90 seconds. If you do this once a week, the mat stays absorbing at full speed.

If it stops absorbing as fast

Over months, the surface fills with mineral deposits, soap residue, and tiny food particles. When you notice water beading up on top instead of disappearing into the stone, the pores are clogged. The fix is sanding.

1. Get a piece of fine-grit sandpaper (180 to 320 grit). One sheet handles a year of refreshes.
2. Lay the mat flat on a towel.
3. Sand the surface gently, in straight lines, with light pressure. You're not removing material, you're refreshing the top layer of pores.
4. Wipe off the dust with a slightly damp cloth, then dry with a clean dry cloth.
5. Stand to air-dry one more time before using.

The mat will absorb water in seconds again. You can do this 3 to 5 times over a mat's life before the stone gets too thin.

Stains

Coffee, red wine, turmeric, beet juice, lipstick (for vanity-tray users), foundation makeup — these will mark diatomite if left to dry. The fix is the same in every case:

1. Make a paste of baking soda and a few drops of water. Should look like toothpaste.
2. Spread the paste over the stain, covering it completely.
3. Leave for 30 minutes.
4. Wipe off with a damp cloth. Most stains lift entirely. Dark old stains lighten significantly.
5. For really stubborn marks, follow with a light sand on that area only.

Don't use bleach, vinegar straight, or dish soap as a stain treatment. They either bleach the stone or push the stain deeper.

What kills diatomite fastest

• Soaking — leaving the mat submerged in water for hours forces moisture too deep, and once the inside is saturated, mold can grow. Wash, drain, dry.
• Bleach — strips the natural color, makes the surface chalky.
• Dishwasher — extreme heat plus prolonged steam plus tumbling cracks the stone within 1 to 2 cycles.
• Standing greasy water — oils plug the pores faster than anything else. Wipe greasy spills immediately.
• Heavy stacking — a stack of cast iron pans on a thin diatomite mat can crack it. Distribute weight or use the mat for lighter items.

The raised feet, specifically

Our sink trays have small raised feet on the underside. Don't pry them off. Their job is to keep air moving under the tray so the bottom dries between uses. Without that gap, moisture would sit between the tray and the counter and grow mildew.

If a foot pops off, glue it back with a tiny dot of food-safe silicone sealant or send us a photo and we'll send replacement feet.

If it cracks

Diatomite is stone. Drop it on a hard floor and it can crack or chip. Small chips on the corner are cosmetic — keep using the mat. A through-crack across the surface means moisture can escape unevenly and the mat won't absorb consistently. Time to replace.

Diatomite is biodegradable. You can crush a retired mat and add it to your garden — the porous stone aerates soil and helps with moisture retention around plant roots.

The honest expiration

A well-treated diatomite mat or tray lasts 4 to 7 years. The mat thins with each sanding, so eventually it gets too fragile to handle. When the surface is so thin you can feel it flex, retire it. Compared to silicone (which yellows and traps moisture underneath) or cloth dish towels (which need constant washing), the lifespan-to-effort ratio of diatomite is hard to beat.

---

Questions? Email lisa@strabella.org. We answer every message ourselves — no support tickets, no chatbots.

— Lisa, Strabella