DIY Concrete Acid Stain

No, I didn’t drop off the face of the earth! I am still here – just have been very busy the past few months.  I’ve been keeping an eye on this blog, but haven’t had time to keep up with posting.  I’ve been working on a lot of projects and hope to post about some of them soon.

This week I worked on a project I had been contemplating since we moved into the house.  The back porch is tiled, but the patio was just plain concrete.  Since it is surrounded by brick, it always stays dirty.  Leaves, mulch, dirt and everything else collects in there and it’s always dirty.

We had acid stained the concrete slab in our first house kitchen and I had been wanting to do that to the patio here.  I had found a local supplier for the acid stain so we wouldn’t have to pay the high shipping costs like we did with our first house.  I picked up 4 gallons of Kodiak (a dark gray-brown) stain, 2 gallons of Copper (a golden brown) stain and two 5 gallon buckets of sealer.

Tuesday afternoon, I began pressure washing the patio to get it clean down to the bare concrete.  The acid reacts with the minerals in the concrete which causes it to change color.  It’s not just a topical stain that can wear off – it actually physically changes the color of the concrete.  So, anything left on the concrete can interfere with the ability of the acid to react.

It took me about 3.5 hours to finish.

Since the concrete was now nice and clean, I decided I better apply the stain the next day instead of waiting for the weekend when David was off.  I used two, all plastic, garden sprayers – one for each stain color.  I contemplated diluting the stain to keep it lighter, but decided just to leave it on the minimum amount of time instead.  (Turns out, I probably should have diluted it too.)  I sprayed the copper stain sparingly in random areas, then filled the rest in with the Kodiak color.  My dad helped by holding cardboard against the brick, but the cardboard got saturated and some still got on the brick.  In hindsight, I probably should have bought a piece of plexiglass to use instead.  Both colors went on yellow and this is how it looked when I was done . . .

It was RED!!!!  Not at all complimentary to our brick.  I would have freaked out except there wasn’t anything I could do about it at that point.

For some reason, the area in front of the garage door took the stain differently from the rest of the concrete.  I let the acid react for 4 hours, then I began neutralizing it with baking soda and water.  That made it start fizzing, “smoking” and turn this beautiful yellow color.

I rinsed the patio 4 more times to make sure the concrete was clean.  At least it doesn’t look as red now . . .

This area still looks different, but once the furniture is back out it shouldn’t be as noticeable.

The next evening, I began applying the sealer.  The hard part was keeping debris off the sections I was working on.  I used the leaf blower and compressor to blow each section off, but dirt still blew back on it.  It turned out to not be as tacky as I expected, so it wasn’t a big deal.  Most leaves and stuff could be brushed off once the sealer was dry.

We applied the second coat of sealer the following night.  Since it is high gloss, there was concern about it being slippery, but our concrete is rough enough that it’s not really an issue.  I wouldn’t recommend running across it when it’s wet, but it’s fine otherwise.

It rained sooner than we expected, but the sealer seems to be working well.

It is much darker than I would have liked, but the color turned out ok.  I was worried about it being hot, but it’s not really any worse than it was gray.  It looks a lot better than the plain gray and it will hide the dirt much better.

We waited about 48 hours before we put the furniture back.  The sealer should last about 3 years before it needs reapplied.