What's the best way to clean brownstone?
I recently redid our brownstone facade and was planing to buy a power washer to clean the stairs and other stone around the house. After doing a bit of research I am concerned that I may accidentally damage the new brownstone. Does anyone have guidance on power washing brownstone? What PSI is safe etc….?
davbrook
in General Discussion 3 years and 2 months ago
17
Please log in, in order to post replies!
17 replies
asaph718936 | 3 years and 1 month ago
Good old soap and water has worked for me over many years! It takes time but i think it is safe
andriywww1990 | 3 years and 2 months ago
for the folks interested in cleaning sandstone and say limestone, in my recent reading about cleaning and preserving those soft stones, i came upon a product that they say and be used to seal these stones. it seals them and still allows them to breath (the problem with the stones is as with any mortar, they put a coat of something on the outside and they trap the water and it freezes and bang). the product is pricey. like i think $150 a gallon. i think made in germany, where all the good stuff is from – like audi.
the post above from elijah pretty much states what is true with the actual stone. touching this stone is risky for any of us and should be done by pros because it cannot be replaced. as i said above, i have removed my great grandfather’s headstone from a cemetery to work on and i admit, i got a little nervous doing so.
but the mortar used to replace the stone is not stone and at worst it can be replaced. at best, prior to our young people fleeing the trades and going to college, a lot of homeowners used muriatic acid to clean a lot of masonry. As i said, in the 1980’s i cleaned a wall i was working on by going down to the mason supply and asking competent people what do to (that was often how we did things back then and all came out fine; we could not make the mistake of asking anyone in an orange apron anything – those fools did not exist). what i am saying is don’t misconstrue genuine stone from mortar and don’t be afraid to read a little and clean your own mortar. if i thought this was so difficult that no one on here could do it, i would set a business up doing just that and take people’s money for really doing nothing but walking around with either a garden spray or a bucket and scrub brush and garden hose. like a day at the water park.
ericonsterling | 3 years and 2 months ago
In minutes, improper cleaning can do more damage than years of aging.
Cleaning is only required to preserve brownstone from pollutants and dirt accumulation. To manage the cleaning, hire a skilled mason and request a sample of their work. The first cleaning approach to try is a gentle water wash or water and non-ionic detergent wash. Avoid using harsh chemicals or abrasive processes like sandblasting or water blasting.
andriywww1990 | 3 years and 2 months ago
I only know what i am about to say about stone only because two weeks ago i removed my great grandfather’s headstone from the cemetery to clean it and recut the letters which were fading. during this process, I did some reading and this is what i learned and dork alludes to it in his reply:
Water penetrates certain porous stones and as it does it leaches out through the sides down below. as it does this, minerals are deposited and those minerals form an outer layer that acts as a protective crust. as i polished away at my great grandfather’s head stone, i realized i was removing this layer (i can see and feel the difference in the next layer just as dork suggests he can see).
in the articles i read about working with soft stones, it was recommended that the hard mineral layer be left undisturbed. i can see doing it once every 50 years but to keep doing it will apparently compromise the stone.
there is probably a lot written about these types of sto ne but if you really want to get in to preservation, read about working with old tombstones. preservationists have a lot to say about this subject.
dorkofwindsor | 3 years and 2 months ago
I have cleaned limestone stairs with vinegar, hydrogen peroxide/soap combo, and dye free laundry detergent. The laundry detergent (HE to minimize excess foam) and scrub brush with a hose rinse worked best – BUT – power washing is easier by a factor of 10. At one point i was using it once a week and it was starting to wear away the top layer of cream finish.
I think if you use it 3 or 4x a year you will be fine. The (disposable) electric power washers are great for this – they are strong enough to do the job but the PSI isn’t heavy enough to do
damage like the gas powered ones could. Smaller footprint stores easily in the basement. They’re junk, but priced accordingly. Mine is 1700 PSI. .
stevecym | 3 years and 2 months ago
Ok, there are people on here who really know because they have done it. I have not. Though i had to hire people who did it. I am not a stone person. I work on the periphery, that is all.
They put a garden hose with little holes in it at the top of a limestone facade and let it clean by dripping down from the top over a period of years.
Others on here can say more.
I also believe you can spot treat a small area of limestone with a poultice.
winbrown | 3 years and 2 months ago
Sorry. I put my limestone facade power washing question on the wrong chain. Thanks for letting me know it’s not advisable. With that understanding, what IS the proper way to clean limestone? Thx!
stevecym | 3 years and 2 months ago
1980? Try bleach in the 1970s. I am not sure the acid runs the color. They simply (i want to say fade away) fall a part.
Guest User | 3 years and 2 months ago
@stevecym – or on your jeans. very 1980s. yuck.
Guest User | 3 years and 2 months ago
@stevecym – or on your jeans. very 1980s. yuck.
stevecym | 3 years and 2 months ago
Don’t get the acid wash in your door locks.
cate | 3 years and 2 months ago
Be careful with the acid wash. Very dangerous.
andriywww1990 | 3 years and 2 months ago
so the tri sodium. it looks like that is still available in NY. it had been outlawed in another jurisdiction i had once lived in (NC).
andriywww1990 | 3 years and 2 months ago
you know, we used to have something called tri sodium phosphate. i used it to clean a masonry wall years ago. the wall had rust stains on it from an irrigation system. i thought they outlawed the tri sodium but there seems to be a replacement for it in home depot. i have never used it and am not sure of its efficacy but it might work with a lot less risk than muriatic. still, if i were doing this i would go right to the muriatic.
most of this stuff you would mix in a 5 gallon pail per the directions (and there may be directions on line for cleaning masonry with muriatic) and use a scrub brush on a pole to apply and work it. and rinse.
andriywww1990 | 3 years and 2 months ago
so i learned this the other day. when they apply new brownstone mortar, they have to acid wash it when they are finished with the application. i have a customer having it done and he told me that was what they were going to do.
with op’s questions, i read it to be that some of the elements had been done previously and the rest recently the done and the previous work had to be cleaned.
cate | 3 years and 2 months ago
I’m a bit confused by the question. Wouldn’t the masons who redid the brownstone clean any dust outside the house at the end of their project? Power washing is never a good idea.
andriywww1990 | 3 years and 2 months ago
are you planning on cleaning brownstone or mortar dyed to look like brownstone?
i would not take a power washer to anything. when they repointed my house, they used a power washer to knock out any loose mortar (that was the result we wanted). my neighbor power washes our new concrete drive out back and that seems ok. but i would not touch a house with a power washer.
if you are trying to clean mortar dyed to look like brownstone, i would consider muriatic acid but i would not use it at full strength. in another life time i used muriatic acid to clean some masonry work (i repointed a historic wall in my early 20’s). i will tell you this, the muriatic acid actually reacts with the mortar (it reacts the same way hydrogen peroxide looks when put on a cut, white fizzing) and it will eat away at whatever the bonding agent is in the mortar. to clean the mortar the acid eats away at the surface. you can brush it on in large areas and then hose it off – don’t let it sit too long (maybe 10 seconds). also, dilute it down a little with water. dilute it down to the point that it still works and then use. i might start at like 20% acid and go from there. if that appears too aggressive, cut it with more water, if it is not working, move to a 30% solution. diluting it will reduce the risk that you eat to far into the mortar. err on the side that a weaker solution and less time is good (if it was not a good wall, say it was some sort of industrial wall, i would say put in on full strength and let it sit for 5 seconds and hose it off).
keep a running garden hose around. you will need it to rinse the mortar off but you will really need it in case you splash yourself. you have a few seconds to get the acid off before it starts to burn. and bear this in mind, if you get a diluted solution of acid on your skin and you are focused on your work, might not feel it burning until you are done hours later and by then you will have a problem to deal with. full strength and you should feel it after 10 seconds or so on soft skin. you will not feel it on calloused skin until it has eaten away at the callouses. wear safety glasses and do NOT BREATH IN THE GAS in from the reaction, especially if you spread this on a wide area. keep the children away. we use a solution of 40% muriatic/60% water to clean old brass and i have to back away as soon as i put it on the metal (back away by like 5 feet); don’t do it on a windy day, it might blow back on you.
go read more about what i am saying here. when did this years ago, there was no internet. i went to the mason supply to get the acid and did what they told me. now they may also have things to neutralize the acid and maybe it is better to use that than just rinsing it with water.
as far as applying anything to brownstone, i have no idea and would not hit it with a power washer as it breaks off in sheets. and i have no idea what acid would do to it, but it might not be good.