Applying Concrete Dyes to a Concrete Overlay
I think the best place to start telling you about concrete dyes is to explain what the options are for coloring concrete.
There are 4 types of topical concrete colorants; water based dyes, solvent based dyes, acrylic dyes and acid stains.
- Solvent based dyes – Dyes are mixed with acetone. That makes them highly volatile meaning that you can blow up a room if not extremely well ventilated. One spark or a pilot light from a boiler, even a spark from turining on a light switch can ignite the acetone. Solvent based dyes also referred to as acetone concrete dyes dry immediately, almost on contact. They create sharp vivid colors. They work on concrete slab or overlays. They are sprayed on with garden style hand pump sprayers. The acetone will eat the pump sprayer hose so either use a sprayer specifically for spraying solvents or move real fast with a cheap sprayer. When you apply on an overlay be careful to avoid drip marks from the sprayer, they will show up and won’t come out. I recommend acetone concrete dyes for professionals who have extensive experience.
- Water based concrete dyes – user friendly. They are not combustable and do not smell. They work great on concrete overlays. They do not work as well on concrete slab, they only provide a tint not deep color. They are sprayed on and evened on with thick Microfiber Mops. Thin inexpensive microfiber mops will cause streaks.
- Acrylic dyes – fairly recent concrete coloring products. They are tricky to work with. Colors can be intense and frequently look a bit like paint on a concrete surface. However they are UV stable and will not fade. They are great for outdoor use when you want specific colors. Acrylic dyes work best when sprayed with an HVLP (high volume, low pressure) sprayer or airless sprayer. Typical garden style sprayers do not create a fine enough mist and can leave what looks like little dots.
- Acid Stains – work well on both concrete slab and concrete overlays. Acid stains are unique. The acid in an acid stain has about 9% acid at full dilution. The acid opens the pores of the concrete and the color reacts with the salts in concrete. Acid stains are limited to earth tones of vaious browns and greens. Acid stains work on concrete slab and overlays. When applying on overlays it is advisable to dilute with water otherwise the resulting color may be a bit too intense.
If you have never worked with concrete overlays it is best to keep the processes simple. One of the best systems for creating a decorative concrete floor is mixing a powdered colorant in the concrete overlay which is an iron oxide pigment. Apply the overlay and let dry for a day.
The next day pour your water based dye into your sprayer and pump up 20-30 times so that the sprayer has solid pressure. When you start spraying the floor the dye can be evened out with a microfiber mop for the first coat. Subsequent coats can be sprayed on with a light mist.
Concrete is never perfectly flat and overlays can produce a slight sandstone finish. The result is natural variation. The dyes will settle into the low areas and create natural variation of color. Pump sprayers lose pressure as you go so there is always an inconsistancy of dye being sprayed on the concrete. This will contribute to slight variation of color and a unique result. No two floors will ever be the same.
If you want to “take it up a notch” you can apply a second or third color in certain areas. This will provide a bit more variation. Keep it light and the result is subtle.
A few years ago working on a restaurant floor we applied waterbased dyes switching browns as we went from area to area. It was real easy and each area had a bit of a different look though very subtle. They had a fireplace in the bar area. I thought itmight be neat to apply some blue, yellow and red in that area. It worked! When the fire was roaring the various floor colors pulled the color of the flames into the floor.
I learned a lot from the result. Subtle changes of color can create compartments on a floor. The water based dyes are easily blended in and out. Or you can just keep it simple.
The dyes need to be left to dry overnight . The following day the first 2 coats of concrete sealer are sprayed on with light coats. They lock in the dyes. Don’t use a mop until applying the finish coats on top of the sealers otherwise the dyes will lift.
Even if you have never done this before if you follow the steps you will succeed. I would recommend staying away from from the Acetone and Acrylic Concrete Dyes. They’re a bit tricky unless you’ve used them.
Acid stains can be applied on an overlay even if you’ve never used them before. I do recommend having a waterbased dye to even out the variation from the acid stain. Frequently the acid stains create too much variation and the dyes will settle them down.
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