Rust on Bluestone FAQ's
Frequent Questions - Rust on Bluestone patio and paving.
We get numerous requests for help on removing Rust on Bluestone. Here are some facts:
"Bluestone" is somewhat of a misnomer, as there are few installations using true Northeastern Bluestone consisting of Sandstone. Some "bluestone" is formed from Limestone.
See the following links: Hunker and Use Natural Stone
Factoid: Many suppliers sell Imported "Bluestone" that is Quarried in India or China and may contain large amounts of Ferrous Metal in the composition of the stone.
It is very important to research the true type of stone you are installing, and to determine the origin. Secondly, understand the Geology if you have Rust Spots or Rust tinting.
Rust Spots generally are caused by large deposits of Iron in the stone, and often the individual stones need to be replaced. Sometimes these spots can be reduced or eliminated by using a Rust Remover like HMK R179.
Rust Tinting is most often caused by Cleaning with Muriatic Acid. Attention Stone Masons - DO NOT CLEAN BLUESTONE WITH MURIATIC ACID!!!
MURIATIC ACID rapidly oxidizes the minerals that may be inherent in the composition of the stone, quickly causing an Orange Tint to the stone. This often happens the next day after cleaning the stone.
Rust Tinting can often be cleaned by using a less aggressive Rust Remover made for softer stone. We recommend HMK R179
Is my "Bluestone" Sandstone or Limestone?
See LINK for a detailed comparison
Simply, Sandstone is harder (quartz based), and Limestone is softer (calcite based). This means that the product you use to remove rust from "Bluestone" is important. We offer two choices:
HMK R777 Rust Remover for Hard Stone (Sandstone based)
HMK R179 Rust Remover for Soft Stone (Limestone based)