Natural Stone Porous Materials Protection Cleaning D.I.Y.

How to conduct an acid sensitivity test on your stone

An acid sensitivity test can be conducted with household vinegar.

Ensuring quality surface protection for your stone – whether it be with a sealer or by being careful with the particular substances you use around a stone – means knowing what stone you’re dealing with. Of course, to the untrained eye, there may not be a boat load of difference between slate and sandstone.

For this reason, from time to time, you may find yourself needing to carry out an acid sensitivity test on your surface. You’re killing two birds with one stone here, if you’ll pardon the pun: You’re helping to identify your stone,  while also finding out how sensitive your stone is to acidic substances.

So without further ado:

1. Gather the necessary materials

Get one eyedropper, and four ounces of household vinegar, lemon juice or 10 per cent muriatic acid. The latter is often used to either balance the pH of swimming pools or get rid of excess mortar in bricks, so you can likely find it in pool and home supply stores.

2. Wear protection

If you’re using vinegar, this isn’t so important. But muriatic acid is highly corrosive, and can cause blindness in the eye or severe burns on the skin, as well as irritation to the upper respiratory tract if inhaled. You’ll therefore want to protect yourself, meaning wear gloves, goggles and even a face-mask.

3. Choose the right area

Depending on the type of stone you’re dealing with, the test can very quickly – and thoroughly – etch the stone. Choose an inconspicuous, out-of-the-way area in your countertop or floor that’s also at least a few inches away from a mortar joint. If dealing with a counter top, apply it to the underside, as it will be both less visible and have less chance of having a sealer like STAIN-PROOF Original™ applied.

4. Apply the acid

Use the eyedropper to apply a few drops of your chosen acidic substance on the stone. Apply it to a limited area, one that’s around the size of a small coin.

5. Evaluate the reaction

There are two possible outcomes of this. The droplets will fizz up on the surface, which indicates that it is calcareous and quite sensitive to acid. If the reaction is muted or non-existent, this suggests that you’re dealing with a silicate stone.

6. Clean up

Rinse the area and blot the surface with a white towel. If you’re dealing with an acid sensitive stone like limestone, there’ll be a dull spot where the droplets were.

Congratulations – you’ve now become much more familiar with the stone in your home.

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