Cleaning a stone wall

A good cleaning and some pointing would probably do the job, so I tried spraying a litre of 3% hydrogen peroxide on the stones under the chimney. It fizzed and smoothed the colour out but left things looking a dull brown.

I'm working above a still-unsanded hardwood floor, so I'd like to keep dripping to a minimum, but ventilation is good this time of year and it's time to try something more dramatic. Sandblast? Muriatic acid?

I'm all ears, but my compressor is a small 4 cfm model.

Thanks,

Rod

This leaves the sandblaster. A vacuum should be able to remove the residue from an unfinished hardwood floor.

I have 15 amp 220 service in the room now to run my shaper. If I went to Princess Auto to get equipment for the sandblasting project, what would I need to buy?

Thanks,

Rod

Old lime mortar creates an instant white-out when it is sandblasted. I know. I have done hundreds of thousands of sq ft of interior brick in old mill buildings. Rubble masonry present some challanges as you are likely to find voids in the mortar.

As a beginner, you will have difficulty doing a good job. Moreover, sandblasted masonry looks different from less destructive cleaning methods. You may not like the effect. It's a personal taste thing.

It is hard to comment on a job I haven't seen. I might advise a homeowner to try scrub brushes and muriatic acid. Use rain gear, face shields, rubber gloves, and forced ventilation. You could also use the hydroflouric acid in the same way. Be sure to dilute it to around 20% of full strength. Yes, it can cause lung damage and skin burns so you need to be very careful and follow mfgs directions. You might want to go to the SureClean website for more info on their various products. I don't know what their site looks like as I used to buy straight hydroflouric from a local marketing company.

On the whole, I think you should hire a professional with lots of experience. Not some wannabe contractor who just bought some equipment cheap at an auction.

So to clean 250 square feet of wall what supplies would I need to go with a 135 cfm compressor? Could you describe the safety equipment I should get?

Thanks,

Rod

Note that I wrote hydroflouric; not hydrocloric. It is not available at Home Depot. A brick dealer may have it in stock. If not, he can order it. There are several different brand names.

It is applied with spray or roller and removed with a pressure washer. The reaction is immediate. No need to wait like paint removers. If you have stubborn spots, it is quite possible to apply and remove 30 times a minute with a helper. I used to be a professional in the trade.