Acid Stain

Acid Staining Retaining Walls With DecoGel™

Mar 18, 2025 Justin Richardson

Acid stain on a vertical surface has one obvious problem: gravity. DecoGel™ solves it by being a gel rather than a liquid — it stays where you put it, so there are no drips or runs, and you can place color precisely enough to stain individual blocks different colors. For retaining walls it is the right tool and the liquid stains are not.

Acid Stained Retaining Wall Before and After Picture

An acid-stained concrete retaining wall.

Shop DecoGel™ Acid Stain →

Test first. Acid stain is reactive, and block from different batches reacts differently. A DecoGel™ trial system on a spare block tells you what 160 of them will do.

What you need

DecoGel™ Acid Stain · a cheap sprayer · a long-handled foam roller · a scrub brush · ProClean Degreaser™ · ProClean Neutralizer™ · EasySeal™ solvent-based acrylic sealer.

Preparation

Mask: Cover anything at risk of overspray with plastic drop cloth
New concrete: Let it cure at least 30 days before you apply anything
Existing concrete: Strip paint, adhesives, oils, dirt and debris — stripper, mastic remover, and a scrub brush with ProClean Degreaser™
Test absorption: Spray water in several places. Not absorbed in five minutes? Etch with CitrusEtch™, neutralize, rinse thoroughly
Dry completely: Before any stain goes on

Application

1: Apply a generous coat with a foam brush or paint brush — about 1/16 in. thick
2: Let it react and develop for 4–6 hours. Richer colors take longer
3: When the color is where you want it, neutralize
4: Scrub the dried excess gel off
5: Spray neutralizer on, leave 15 minutes, rinse until the water runs clear
6: Let it dry at least eight hours before sealer
7: Two thin coats of EasySeal™
Cleanup: Neutralize tools, then wash with degreaser and warm water

Do not panic at step 6. As it dries the color looks chalky and faded. It comes back the moment sealer goes on — that is normal and not a sign anything went wrong.

Deco Gel Stained Stenciled Concrete Wall — A DecoGel-stained wall.

Acid Stain Retaining Stenciled Concrete Wall — A gel acid-stained retaining wall.

The Great Wall of Glenoma

Larry and Tina bought a few acres on a south-facing slope and had to cut into a bank. They built the wall from about 160 ecology blocks — 300 lb each, 4 ft × 2.5 ft × 2 ft — and then decided it looked too commercial to leave gray.

Wall: ~160 ecology blocks, 300 lb each
Color: Cola DecoGel™
Sealer: Solvent-based satin acrylic
Cure before staining: Three months
Application time: Two hours for the whole wall, two people
Neutralized with: Baking soda and water, by sprayer

“We looked into different staining methods and decided on the acid stain for longevity and virtually no maintenance… We let the blocks cure for three months and then pressure-washed them to make sure they were clean. Three days later, we stained the blocks with the gelled acid stain. We used a cheap sprayer and long-handled foam roller. My wife and I were able to apply all the acid stain in two hours… We are absolutely satisfied and get many compliments. We call our work the Great Wall of Glenoma for the little town it is located in. The wall now blends in with the hillside and doesn't look commercial.”
— Larry and Tina

The Great Wall of Glenoma, stained in Cola DecoGel™.

A note on their method: they neutralized with baking soda and water rather than a dedicated neutralizer. It works, and it is what they did — but ProClean Neutralizer™ is formulated for the job and takes the guesswork out of the ratio.

A 120-foot white wall, stained brick by brick

Julie's retaining wall was poured in a brick-pattern form and was, in her words, a bright white eyesore. Because DecoGel does not run, she could stain individual bricks in different colors — which is what makes it read as real brickwork rather than a colored wall.

Colors: Coffee Brown, Black and English Red DecoGel™
Length: 120 feet
Sealer: Solvent-based satin acrylic
Applied with: Paint brush, brick by brick

“I used Direct Colors Deco Gel concrete acid stain two years ago to stain a 120 foot white concrete retaining wall. The wall now looks great and I get a lot of compliments… I took a clean broom to wipe the concrete wall from any debris. I applied the Deco Gel with a paint brush. I spot stained occasional orange bricks then did the rest with coffee brown (not black). Then I used a sprayer with water and baking soda to neutralize the stain after it remained on the wall for many hours.”
— Julie J.