May 25th 2021 / General Stone Care
Stain Removal Guidelines: Understanding Stains 101
A stain is generally considered a discoloration of a stained material. However, not all discolorations count as stains. For example, when you spill some liquid onto a piece of fabric, which is typically absorbent, the fabric material absorbs the liquid. If the liquid is plain water, the stain will be temporary, and the fabric will resume its original color once it dries. However, if you spill coffee or cooking oil on the fabric, it will absorb the staining agent and possibly become a permanent stain unless you remedy the situation.
Below is a short guide on stain removal.
Is Bleaching Staining?
As previously noted, not all discolorations are stains. Technically, if you spill bleach of a fabric piece, it will be discolored but can hardly be defined as staining. This is because bleaching is permanent damage to the dye that originally made the color of the fabric.
All stones are generally considered absorbent, subject to exceptions. For example, some individuals don't consider diamonds or any other precious gems as absorbent. However, this claim may be valid since a gemstone is not a stone. A gemstone is made of one crystal of one single material.
All other less valuable stones are the composition of many crystals, either of the same mineral or different minerals bonded together. The space between the molecules of minerals is the primary determinant of a stone's porosity.
Since a stone's porosity generally varies, so does its absorbency. Some of the stones are highly dense, meaning their porosity is minimal. This means that the absorbency of such stone types is so marginal that it can be considered irrelevant by all practical intents and purposes.
Other stones depict medium porosity, while others are highly porous at the very end of the spectrum.
Due to their natural absorbency, most stones absorb liquids. Therefore, a true stain will occur if such liquids are staining agents. It is vital to note that an actual stain should be darker than the stained surface. If the stain is lighter, it is either a corrosion mark (acid etching) or a caustic mark (bleaching). An actual stain is a discoloration of the stone produced by the staining agent that the stone absorbed.
Light-colored "Stains" on Stones
A lighter-colored stain has nothing to do with a stone's porosity or absorbency. Instead, it has a lot to do with its natural chemical makeup, It is still considered a discoloration, but it is actual damage to the stone surface.
All the stains that appear like water rings or water spots are typically corrosion marks (etches) due to chemically active liquids that came into contact with the stone. Unfortunately, these stones often turn out to be sensitive to harsh chemicals, including but not limited to acids.
Stones Sensitive to Harsh Chemicals
All calcite-based stones such as marble, limestone, marble onyx, travertine, and more are highly sensitive to acids or different harsh materials. Upon exposure to acids, these stones will etch readily. Select granites mixed with a certain percentage of calcite binders or acid-sensitive materials (instead of 100% silicate rock) will also etch readily upon exposure. Many slates will etch too.
Understanding how stains work on different surfaces is the first step to dealing with stains. It is imperative to understand that not all discolorations are stains. Removing stains often requires the use of chemicals or special solutions.