Use of potassium permanganate
Potassium permanganate is an oxidizing bleach sold as a purple liquid or in crystal form. It is chemically obtained by the action of carbon dioxide on an aqueous solution of potassium manganate.
Potassium permanganate has the ability to remove last traces of dye, ink, tannin and mildew stains. It replaces sodium hypochlorite, which can not be used on wool or silk.
Potassium permanganate, as with other strong bleaches, can affect fluorescent dyes, so testing is required even on white fabrics.
Potassium permanganate can be purchased from your chemical suppliers and also from A.L. Wilson Chemical, which they sell as an ink remover. You can also get Potassium permanganate in supermarkets and home goods stores that sell chemicals for pools.
Before using potassium permanganate it is important to note all its characteristics.
Oxidizing agent — works by adding oxygen to the stain.
Alkaline by nature. Although it is alkaline in nature it can still be used on wool and silk.
To accelerate the bleach, acids are used. It is not a common practice to accelerate.
After use, it will leave a brown discoloration on the fabric. The discoloration can be removed by any one of the following:
Peroxide and acetic. This is the best agent to remove the brown discoloration.
It is a very good agent for removing last traces of dye, ink and mildew.
Rules for effective use
Potassium permanganate must be used only on last traces of staining.
It is the most effective bleach for mildew on wool or silk.
Heat accelerates this bleach but it is not recommended.
How to use
Spotting board method
Dissolve a few crystals in a spotting bottle using cool water. Using only a few crystals and a six-ounce spotting bottle will give enough strength of the potassium permanganate. As long as it has a deep purple color, it is strong enough for effective use.
Use a Q-tip to apply to the stained area. A brown discoloration will then occur.
Wait about 20 seconds and flush the area. It is safer not to accelerate it with heat.
To remove the brown discoloration, use peroxide and acetic. You can also use oxalic acid or sodium hydrosulphite.
Flush the area thoroughly.
You do not have to neutralize the area after flushing since the products used to remove the discoloration are acid in nature.
Fill a plastic bucket with cool water.
Put in enough potassium permanganate so a medium purple color is obtained. For a stronger concentration increase the color intensity.
Soak the garment for five minutes.
Put it in a bath of sodium hydrosulphite or oxalic acid. Use one or two ounces of hydrosulphite or oxalic acid per gallon of water.
Summary on bleaches
All bleaches are accelerated by heat and metal.
Every 18°F increase in temperature doubles the chemical action.
Always bleach clean garments. Bleach does not remove soil.
Always rinse when using alternate bleaches.
Never crowd a bleach bath.
Bleach should be thoroughly dissolved before immersing garments.
Never bleach in metallic containers.
When using stronger bleaches, the bleach bath should be watched.
Rinse and neutralize bleaches after use.