Removing Mineral Stains From The Surface Of Granite

[steelepulse]

I've got some outdoor granite and over the years where some potted plants have been, a ring of what appears to be a mineral stain has developed. Using soap and water does not work in removing this. Is there anything that can remove this stain?

On another type of granite I have some rust stains that has developed from some overhead rust dripping down. Any way to remove these stains?

[howto]

One can try the following...

As with all chemical products,

Wear protective clothing such as gloves and goggles.

Read the previous sentence again.

Don't drink and mess around with chemicals.

For the "Mineral Stain":

Most likely lime scale or fert residue.

-White Vinegar, straight, non-deluted

Typical Thai vinegar is 5% strength from the grocery store.

Saturate a piece of facial cotton

place it on the residue for a day or more.

Keep it wet with vinegar.

Perhaps it will work.

- Muriatic acid.

Muriatic acid is HCl (Hydrochloric acid).

Industrial HCI is around 40% strength.

Dangerous stuff.

HCI is diluted to around 20% strength for Muriatic acid.

Still dangerous stuff.

Read about it before using it.

Remember the protective clothing.

Muriatic acid is available at most hardware stores.

Cost around 100 baht / Liter or so.

Commonly used as a brick cleaner/etcher.

Exercise caution using this on granite.

Test on just a small spot, not an area.

Dilute to 50% with water.

Apply with a cotton ear-bud.

Wait 10~15 minutes, check.

ok, then use it.

not ok, reapply, Increase wait time to 30 minutes.

ok-use it

not ok, try full strength acid on that spot.

wait 10 minutes.

Should have some sign that it affects the residue.

if not, give up on muratic acid.

Clean-up:

Flush very well with water,

then wash area with detergent/soap.

Muriatic acid will not remove the rust stains.

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For the "Rust Stain":

These are excellent rust converters...

Citric acid, Phosphoric acid, Oxalic acid

They can be had in powder form often from chemical distributors by mail order.

Typically in 1 kilo quantity.

Perhaps this company has them...

Northern Chemical 053 223-866(7)

Note: You do not need the "food grade" version.

These are also dangerous.

Read the safety precautions.

Wear the protective clothing.

Usage:

Mix the acid powder/crystals with water,

to arrive at a 5~10% solution by strength.

Saturate a cloth or facial cotton pads,

place on rust stain.

Leave it overnight.

Rinse it off in the morning.

Clean residue with a nylon kitchen sponge and soap.

Should work, if not, increase strength.

Phosphoric acid is also commonly known as "Naval Jelly" (a thick gel).

Automotive Radiator Flush may work.

They often uses Phosphoric or Oxalic acid.

Usually listed in the back of the container.

Find it at the local automotive parts store,

I know it's available here in los.

Commercial products:

Back home, in the past, I have used the below products. They work.

I've never seen them here in los, but I have not looked.

Likely difficult to find here...

Summit Products

http://www.summitbra...s/rust_removal/

- "Instant Rust Out"

Liquid, 5% Oxalic acid and < 2% Boric acid

- "Super Iron Out"

Liquid, 5% Citric acid and some other stuff

- "Super Iron Out Outdoors"

Liquid, 10% or > Oxalic acid

Malco Products (makers of Spray-n-Wash and Brasso)

- Zud Heavy Duty Cleanser (Powder)

http://www.malcopro....=172&Itemid=864

Powder, 10% Oxalic acid and pumice,

Could be an issue with scratching or swirl marks on granite.

------------

If all else fails try WD40

this "Wunder spray" purportedly works for anything on anything.

Well it makes me wunder. But take a look...

http://www.thaivisa....dient-of-wd-40/

Hope this helps.