We have recently had several requests from clients to provide some recommendations on how to remove hard water marks from glass panels so we decided to test various products and techniques to establish the best products and the best techniques. We purchased several branded products that all claim to remove hard water marks and we compared them side by side.

Hard water marks are caused by minerals that are present in the water. The water evaporates leaving the minerals stuck to the glass. Coating the glass with USGF DSS Reactive Sealer minimizes the deposits and but they can still build up, especially if the glass is sprayed daily by an irrigation system.

From a practical perspective we wanted to use a technique where we could saturate the glass with a chemical solution and then just rinse it off. Scrubbing every inch of glass with a cream or paste was not really a practical method for our application.

Many of the products we tested were creams or gels that needed to be applied and worked into the glass surface to abrade away the water deposits. Most worked really well and would be fine for small windows or a shower door. This technique was not really practical for large panels of glass.

We tested each of our products on a small area to see how effective they would be. They all did well but when we scaled up to a large panel most were not practical.

The two products that scaled up well and really provided results were HARRIS 30% VINEGAR and EACO CHEM ONE RESTORE.

We applied the HARRIS 30% VINEGAR (Home Depot/Lowes) to the glass using a spray bottle. The then wiped the surface with a micro fiber cloth on a stick for a few minutes making sure to keep the solution moving and refreshed. We then washed the glass with water and squeegeed off the excess. The results were surprisingly good with all but the most stubborn stains/marks remaining. The solution will kill foliage so be careful. On a hot day the solution will evaporate so wear a mask and gloves.

The EACO CHEM ONE RESTORE is an acid based product that is more aggressive than Vinegar. Definitely wear gloves and a mask. The acid will effect metal so do not leave this product sitting on the metal posts for very long. Spray it on, wipe the surface and rinse with water and squeegee off the excess. This was a very effective chemical for our application. I left the glass in perfect condition.

REGULAR CLEANING – Once all of the general deposits had been removed we wanted to establish the best method for just cleaning the glass. We have traditionally used a 20% solution of Isopropyl Alcohol and Distilled Water. We would spray it onto the glass and wipe it thoroughly with a microfiber pad on a stick. This can sometimes leave a cloudy residue on the glass. We then tested the HARRIS 30% VINEGAR using the same technique. A light spray onto the glass; work it with the microfiber pad and let it dry. We found this to be a very effective method to clean the glass and leave it streak free.

CONCLUSION – To remove heavy mineral deposits try the HARRIS 30% VINEGAR product with a microfiber pad. If the deposits are stubborn then move up to EACO CHEM ONE RESTORE making sure to take safety precautions and rinse thoroughly.

When the deposits have been removed and the glass is clean, spray and wipe the HARRIS 30% VINEGAR solution to finish with a nice clean panel of glass.