what is white haze and how to remove

[engrav]

Hi

See pic below

What is the white haze on the slate surrounding the pool and
how to remove

could this be pool splash out over 30 years?

comes up with Nyalox brush; does not come up with muriatic acid

thank you

 

[JoyfulNoise]

Is it everywhere or just near the pool?

You didn't really give a lot of information such as what's in your pool water, splash out, etc. that said, my shot in the dark guesstimate would be simple evaporate from the pool water, ie, salt, calcium carbonate, etc.

Dilute acid mixtures often help but if the grout between the slate is dark colored you have be really careful about bleaching it. Try some dilute vinegar and soft nylon brush with a fresh water rinse.


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[engrav]

thank you

vinegar nylon brush fails
muriatic acid fails
only Nyalox powered brush succeeds but sooooo painful

as for water
pool water is well water with bleach, bicarb, calcium chloride, muriatic acid

well water has no Fe but does have low level manganese and is "moderate" hard

thank you

 

[JoyfulNoise]

Was the slate ever sealed?


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[engrav]

Was the slate ever sealed?

thank you
zero records with this house, none, zippo
I could email previous owner and ask, I will do so

I just tried a wire brush, takes the stuff off, slate looks nice after, much like a new slate (we have some new)

thanks again

 

[JoyfulNoise]

Well, slate is a good material because it's the least porous of all stones typically used for flooring. It very impervious to water infiltration (one reason why it was used extensively in roofing). So what's there are probably water stains and the nylon wire brush is probably just lightly abrading/polishing the surface and removing the adherent crust. You could wire brush everything back to a high polish and then try a stone sealer.

I did read on another site that slate tiling can be cleaned with a slurry of baking soda, water and lemon juice. I think the ratio was 1/4cup baking soda, 1 tablespoon lemon juice and 1/4cup water. Trick is you need to rinse with distilled water since tap water has minerals in it that will stain the cleaned surface. I guess that's why the recipe was for indoor shower slate tiling.


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[engrav]

thank you

Nyalox brush or wire brush will take it off but was hoping for a liquid that would be faster and no kneeling

but maybe can't get there from here
so maybe brush it is

but surely seems like some liquid should soften it up (muriatic acid seems to do little)
will keep searching

thanks again

 

[engrav]

Hi

tried CLR on some old slates

CLR takes off the white haze with hand brush quite easily
CLR does not visibly hurt slate

it contains
gluconic acid, lactic acid, sulfamic, and glycolic ingredients
it is phosphate free

away from pool edge it can be rinsed
but near the pool edge on the coping if some slopped into the pool
would gluconic acid, lactic acid, sulfamic, and glycolic ingredients be bad?

am beginning to wonder if this is dried pool splash out, why?
it is mostly located near the pool; the slates further away are much less involved
since pool is not distilled water, perhaps years of splash >> white slate haze

 

[JoyfulNoise]

It is well known that scale caused by evaporite deposits can get hardened with age. It starts of first as calcium carbonates and chloride salts but other minerals can become embedded in the scale (magnesium, iron, silicates, etc) and harden it to the point where dilute acids no longer work effectively. I have seen this on faucet fixtures in my home as we do not have a water softener. Calcium deposits build up along with magnesium and silica. When they build up a thick crust on the aeration heads I take the heads off and soak them in CLR overnight. You can see bubbling develop on the scale but, even after an overnight soak, there is still crust left on the fixtures. You can rub the remaining crust off by hand as the CLR has dissolved the carbonates but there are still those undissolved solids left behind that only come off with mechanical scrapping.

I imagine your 30 year slate is similar. It develops that white crust over time and it hardens it pretty good against dilute acid washing. Perhaps, after you get it looking like new with the CLR, you might consider sealing it to help avoid future deposits. Just make sure sure you use a high quality sealer that is meant for slate.

 

[Pool Clown]

If you decide to use wire brush that is not stainless, be mindful of the fact that bristles will come off the brush and can rust the deck, and can make it to the pool!

 

[engrav]

thank you

that might be it; decades of dried splash out on unsealed slate

and CLR removes it quite nicely, with a hand brush, power not needed
maybe can even rent a circular powered scrubber and do large areas away from coping
then do coping by hand

and web reading on CLR says IF SERIOUSLY RINSED is Ok on
shrubs
coffee makers
coffee pots
drinking glasses
ice maker
washing machines

which suggests that a little "splash in" would not be all that serious

- - - Updated - - -

If you decide to use wire brush that is not stainless, be mindful of the fact that bristles will come off the brush and can rust the deck, and can make it to the pool!

ouch

am now thinking that since it comes up so nicely with CLR
I should try just a mop; no bristles, no bending
and just a dampened rag on the coping (splash in would be minimal)

so mop and rag is the next experiment

thank you all

- - - Updated - - -

Was the slate ever sealed?

heard back
slate has not been sealed for a decade at least

thank you

 

[JoyfulNoise]

Yeah, CLR in the coffee maker....never. The funny part is CLR used to just be 10% HCl but then they were forced to reformulate it using those organic acids. I've used sulfamic and oxalic acids in my previous working life and there is absolutely no way I'm putting that stuff in my coffee maker. Distilled white vinegar works just fine. CLR only gets used for calcium scale on the faucets.

However, I'm sure a little splash in the pool won't hurt anything. Glad to hear it works well on slate.


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