Making Concrete look Weathered

[Quickstep192]

I’m making some artsy castings out of countertop concrete and I’d like to make the concrete look weathered as though it’s been beaten by years of wind and rain and had gotten that buff color of aged concrete. I’m adding dye, but that doesn’t make it look aged.

Any ideas?

 

[PCustoms]

I’m making some artsy castings out of countertop concrete and I’d like to make the concrete look weathered as though it’s been beaten by years of wind and rain and had gotten that buff color of aged concrete. I’m adding dye, but that doesn’t make it look aged.

Any ideas?

Colored release compound to contrast the dye, or go with a 2 step stain process

 

[Quickstep192]

Thanks. I think I’m close to achieving the color I want, but I’d like the surface to look a little bit eroded.

Here’s a picture of the look I’m after.

 

[tncatadjuster]

If you catch it green you can steel brush it (stainless) and put some wear marks. Once set up it usually show tool marks. How intricate is the piece?

 

[Quickstep192]

My piece is intended to be a re-production of the picture. The one in the picture is 24” x 25”. My repro is 7” x 7” with the details scaled accordingly.

 

[PCustoms]

Thanks. I think I’m close to achieving the color I want, but I’d like the surface to look a little bit eroded.

Here’s a picture of the look I’m after.

Course salt in the tool, then wash it after? Seen driveways done with rock salt, I'm thinking more like coarse table salt for this scale.

I've also used dry grout.

Or maybe just a pressure wash as it cures.

 

[Quickstep192]

I just read something about dusting the mold with baking soda before pouring the concrete. Apparantly, the baking soda reacts with the concrete making it rough? Anybody heard of that?

 

[mike93lx]

Can you find an example picture of what you want to achieve? Might help with recommendations

 

[Danno1]

.

Muriatic acid (HCl) will etch the surface. Wear PPE!

.

 

[carlaisle]

Sand blast it?

 

[tncatadjuster]

Salt as mentioned might be your best bet, it was used for centuries for non slip.

 

[BurtEggley]

Is the mold is poured upside down? If so, your surface would be created by the mold or by etching the concrete afterwards. Acidic fertilizers washing across concrete will do that too. I think to create that surface on the mold, you'd need to etch it or spray it with something that would not make it hard to release the concrete from the mold. I would guess that sand blasting will be too even. It will also haze any stones that show. Salt does it by drawing in moisture which then freezes and breaks the surface up.

 

[Codyboy]

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Muriatic acid (HCl) will etch the surface. Wear PPE!

.

25 years ago we had a gunite pool built and at one step they used muriatic acid on the plaster or gunite , can't remember.
There were 4 guys inside the empty pool that had very stiff brooms and throwing gallons and gallons of undiluted muriatic acid on the walls and scrubbing like mad men.
They were all barefoot.
Ive always wondered how caustic it is to human skin.

 

[mike93lx]

.
Ive always wondered how caustic it is to human skin.

Incredibly.

There is no way they were walking around in the concentration That is generally used for this purpose, though. The PH is between 1 and 2 and they would have massive, debilitating chemical burns

 

[Codyboy]

Incredibly.

There is no way they were walking around in the concentration That is generally used for this purpose, though. The PH is between 1 and 2 and they would have massive, debilitating chemical burns

Well, they were.

 

[mike93lx]

Well, they were.

OK then

 

[tncatadjuster]

Rock salt will create a void once the water dissolves the salt, no freezing required. The Japanese would add it to the paint and once dried and slightly scraped, the salt would then dissolve creating little craters with sharp traction points.

 

[racecougar]

Well, they were.

Must've been like the acid lake in Dante's Peak over there.

 

[Quickstep192]

I’m thinking of dunking my concrete casting in a Muriatic acid bath to erode the surface.

The concrete has now cured for about two weeks.

How much longer to wait?

What concentration of acid:water?

How long to leave it submerged?

Then rinse and bathe in baking soda solution, right?

 

[PCustoms]

I don't get it, you've got another thread about micro porosity, but you want to dunk it in acid?

 

[BurtEggley]

Bury it in the back yard. Come back next year with an archeology team so you can say it is belonged to an ancient civilization after it ages in dark black acidic soil for a year. Then write a best seller about the discovery, and deny you ever chatted with anyone on the GJ.

 

[Quickstep192]

I don't get it, you've got another thread about micro porosity, but you want to dunk it in acid?

Yes, I figured an etched surface will disguise the imperfections. Also, I want it to look weathered.

 

[PCustoms]

Yes, I figured an etched surface will disguise the imperfections. Also, I want it to look weathered.

Pressure wash or media blast

 

[Quickstep192]

Not on my list of toys tools

 

[PCustoms]

Not on my list of toys tools

Yet

 

[BombShelter]

We've got this place locally that can tell/sell you how to do anything with concrete.

Masonry Equipment – Minneapolis, MN

Schafer Equipment Company in Minneapolis, MN, can be reached at 612-861-2268.

www.schaferequipmentcompany.com