Removing plaster splashes from feature brickwork

[joe90]

We have a feature brick fireplace and when the wall next to it was plastered it has left a plaster film on the brickwork edges where the plaster was washed off. I have tried brick acid ( 50/50) without much success, has anyone got a better idea for cleaning the bricks please.

[lizzie]

I had plaster splashes on a feature wall in last house. Tried everything couldnt get rid of them.  In the end I bought some brick tint on line and did a very careful job on the splashes. It worked a treat, dont paint whole bricks though that looks awful just used an artists brush and feathered the splashes. I bought the samples of the brick colour only cost a few bob and was far more than I needed. If your splashes are fairly small diameter I would try this approach.

[Jeremy Harris]

Brick cleaner won't dissolve it, as it's dilute hydrochloric acid, however, I believe that gypsum should be soluble in dilute sulphuric acid (battery acid), and it has limited solubility in just water.  Acetic acid (vinegar) may also very slowly dissolve it, but that's really about it.

 

If it were me then I'd try dilute sulphuric acid, at about battery acid strength, on a small area and see if that works.  It's unlikely to work quickly, I'm afraid, as the solubility of gypsum in it isn't that good.

[Luckylad]

On 01/03/2018 at 11:57, JSHarris said:

Brick cleaner won't dissolve it, as it's dilute hydrochloric acid, however, I believe that gypsum should be soluble in dilute sulphuric acid (battery acid), and it has limited solubility in just water.  Acetic acid (vinegar) may also very slowly dissolve it, but that's really about it.

 

If it were me then I'd try dilute sulphuric acid, at about battery acid strength, on a small area and see if that works.  It's unlikely to work quickly, I'm afraid, as the solubility of gypsum in it isn't that good.

Hello 

We use baking soda to clean our plastering machines,do you think it could be harmful in any way to them?

Theres very hard rubber inside the machines and  I often wonder if it'll do long term damage. 

Thanks.