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Iron Sulphate Concrete Stain Lawrence Lile, P.E., LEED AP |
Step 2: Materials You'll need |
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Step 3: Experiment Buy some concrete pavers with a smooth troweled finish at a local hardware store. Arrange them out in your yard, and play with stains and finishes. When you are done, use them in garden paths or under your hose faucet. If your slab is already done, make test patches in closets, under your future dishwasher or in the future garage. Try out all your materials and sealers, application methods, and so on. |
Clean the floor
with mild soap, like Murphy's oil soap, and some
scrapers. I used a sheetrock knife, screwdrivers, and whatever
was handy to pick up glue, spilled paint, and sheetrock mud
dollops. Anything stuck to the floor will show, so be
meticulous. |
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Clean it again
with soapy water, then with clear
water. Use a shop vac to slurp up the excess. Be careful
with the shop vac, the wheels will make dirty tracks across the
floor. I carried the shop vac when it was full of water to avoid
this effect. |
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You will be standing in 1/4" of water, operating an electrical machine. Plug your machine into a Ground Fault Circuit Breaker. This is the kind of outlet with a "test reset" button. If you don't have one, get one installed. I knew this, ignored it, and got a nasty shock from a pinhole in the extension cord insulation. You can buy ground fault adapters at any good hardware store, if you don't have one. | ![]() |
Step
6: Masking Iron Sulphate will stain wood black, even through varnish. Mask wood carefully. The stain mixture will run right under masking tape on the floor, so use duct tape to mask lines or at doorways where you are changing to other colors. Duct tape will leave a sticky mess on the floor if you leave it too long, so peel off the duct tape as soon as possible. Use plastic for masking floors, you can use masking paper on walls, which I found easier than using plastic. If you stain the floors before the base trim goes on, you don't need to mask the walls. |
Keep it mixed, the iron sulphate will settle out. Strain it through a cloth with a funnel into your garder sprayer. Never put anything in a sprayer that hasn't been strained, they clog up fast. Struggling to clear a clog out of the nozzle will cause you to make unsightly drips, and also emit words unbecoming of a sailor. |
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I applied the mixture to a dry floor, although Cathy Moore applied it to a wet floor. Either way works well, I found it easier to see where I had sprayed using this method. Then I used a long handled scrub brush to really work the stain into the floor, apply a pattern, and move the stain into corners and crevaces. You can also accomplish this with a household sponge mop, I liked the scrubbing brush because I though it left a better pattern. Note the socks, which leave less footprints than shoes or bare feet. When you first apply the stain, it has no color at all, but it starts to develop within 5 minutes. |
Step 8: Dry, then Dust, Then Wet Allow the floor to dry. Dust it with a dust mop. (wear a nuisance dust mask) You aren't trying to remove any dust, just redistribute it. Much of the stain will lay on top of the concrete at this point, in the form of iron oxide dust, and you are redistributing it, removing brush marks and footprints. |
Use a piece of the floor buffing pad you saved from step 5 to scrub the white stains, you can rub some red into them and make them not show. A sandblaster is the only thing that will truly take them out, and I don't recommend this. |
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The top half of this photo shows the caffeinated stain. The bottom half shows the stain with no coffee added. The photo does no do justice to the contrast between the two - the coffee stain looked much darker to the eye. |