September 12, 2018 Off By Torin Dixon

Muriatic Acid will Ruin Bluestone

One-Day after Cleaning Bluestone with Muriatic Acid

Problem with Rust on Bluestone

We receive calls each week from panicked homeowners shortly after installing their expensive Bluestone Pavers when their Stone Mason mistakenly uses Muriatic Acid to clean the grout residue, and within hours their beautiful bluestone turns yellow (see image above, lower area) due to the acid oxidizing the metals in the composition of the stone. The acid has created Rust on the stone.

Is this Problem Fixable?

Fortunately, the answer is YES, this issue can be corrected, and it doesn’t require hiring expensive professionals, but will require a bit of DIY ‘Elbow Grease’, but it isn’t as hard as you may think. We offer a professional grade Rust Removing Combo to reverse the rust tinting or staining.

Before you order, please note that there are different types of “Bluestone”, there are quartz-based, and calcium-based “bluestone”. Any more, it is very difficult to find geologically true Bluestone. Because of this, there are many imported stones that may look like Bluestone, but perform poorly. Many stones imported from India and China have iron crystals in the composition of the stone, and ACID’s act like an accelerant to turn small iron crystals into BIG RUST SPOTS on “Bluestone” pavers. It is important to test your stone first to know if it is sensitive to acid cleaners. See numerous posts HERE


  • Order the HMK R777  & R155. This combo includes the Rust Remover and the HMK R155 Intensive Cleaner which neutralizes the acid and cleans any rust residues. It also prepares the stone to receive Impregnating Sealers to prevent or slow down any re-formation of rust oxidation. Stopping moisture infiltration is the key.
  • Make sure the ambient temperature is between 50-75 degrees. Very lightly mist the stone so that the first “drink” the stone takes is a little moisture, so the R777 doesn’t just get absorbed into the stone. This will help the R777 Rust Remover be more effective.
  • Protect all adjacent surfaces. Apply undiluted HMK® R777 generously and evenly and work into the surface using a scrub brush,  or a suitable pad. Always apply to the whole surface, but if you have isolated stones that have severe rust spots, you can spot clean these first by placing saturated rags (soaked in HMK R777) then cover these spots with plastic and allow to activate for 12 hours. For these rust spots, jump down to next step to neutralize.  Place towels soaked with R777 onto the surface to keep the surface wet and to ensure that the treatment does not dry out. For large areas, I have used a cloth painters drop cloth to cover the area. It is VERY IMPORTANT that the area is completely covered and saturated . This will help to insure that the Rust will be completely dissolved.
  • Immediately after application, cover the surface with plastic and let sit for 12 hours. Remove any remaining product on the surface after 12 hours and clean the area thoroughly using HMK® R155 Intensive Cleaner -acid free- diluted with clean water about 1:10 and remove the dirty liquid.
  • Afterwards, rinse the area thoroughly with clean water, and allow to dry or drain. If water is standing, squeegee off any standing water. Note: If you do not have good drainage, it is even more essential that you protect the stone from moisture by using a quality Impregnating Sealer.
  • Allow stone to dry for 24 hours. Placing box fans to circulate air can help dry the stone.
  • Once you are happy that all the rust has been removed, you are ready to Protect the stone. For severe rust stains on isolated stones, as second application of the R777 Rust Remover may be needed.
  • We suggest HMK S234 Silicone Impregnator which also has stain protectants to prevent food stains and stains from leaf and yard debris. Another option is using a Silane Impregnator like HMK S731, but this product requires keeping the stone dry (no rain) for 48 hours after applying the sealer.

By using these professional grade products, you can remove rust stains caused by moisture, or accelerated by the use of Muriatic Acid.

If you need further assistance, please contact us at 800-380-6881

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