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Bleaching Chemicals

2 Mar 2022 6:00 AM | Dawn Hargrove-Avery (Administrator)

Bleaching Chemicals

Bleaching chemicals are used to react with a stain in order to render it colorless (camouflage it). Some types of bleaching agents will also whiten or brighten fabrics. The bleaching action either adds oxygen to the stain (oxygen bleach) or removes oxygen from the stain (reducing bleach). Since bleaching must be done in the presence of water, the bleaching agent must either contain water or be mixed with water.

Summary on Bleaches

1. Bleaches do not remove soils; therefore, the garment must have been dry cleaned or laundered prior to the application of the bleaching agent.

2. Test the fabric on an unexposed area of the garment to test for colorfastness.

3. Since bleaching agents become more aggressive when used with acids or alkalis, test for colorfastness with the chemical used to catalyze the bleaching agent

4. Bleaching agents will double in strength (and will become more aggressive) for every 18º F. of heat applied.

5. Bleaching agents are accelerated by metals. Only use plastic buckets or epoxy plastic or stainless steel sinks.

6. Because bleaching agents can harm fabrics and dyes, they are used as the last step for stain removal.

Rules for Bleaching

1. Always bleach clean garments.

2. Never crowd the bleach bath.

3. Bleaching agents should be thoroughly mixed and dissolved before immersing the garment in the solution

4. Rinse and neutralize bleaching agents after use.

Oxidizing Bleaches

Hydrogen Peroxide

1. Contains stabilizers that prevent the loss of potency.

2. Should be kept refrigerated

3. Accelerated by ammonia and heat (will become more aggressive on dyes- test)

4. Use 3% 10 Volume Hydrogen Peroxide

5. Used primarily as a spotting board bleach.

6. Used to remove the last traces of tannin, protein, and scorch stains

Sodium Perborate

1. Is alkaline by nature

2. Accelerated b an alkali (not recommended)

3. Purchased in powdered form.

4. Used primarily as a bath bleach for the removal of tannins, proteins, some inks, and topical medications.

5. Used on silk and wool as a whitening agent

6. Slow acting bleach

7. Use 2ounces per gallon of water at 100ºF.

8. Must be neutralized with an acid bath (sour).

9. Safe on all fibers and some dyes.

Sodium Percarbonate

1. Similar to sodium perborate.

2. Releases oxygen more rapidly

3. Dissolves more rapidly in cooler temperatures of water.

4. Use the same way as sodium perborate.

Sodium Hypochlorite (Chlorine bleach-Not commonly used)

1. Cannot be used on animal fibers such as wool or silk.

2. Cannot come into contact with ammonia- will emit harmful toxic gasses!

3. Dangerous to most dyes

4. Alkaline by nature.

5. Accelerated by acids.

6. Bath mixture- ½ ounce per gallon of water (bath)

7. Board mixture- dilute 50-1 for board use.

8. Must always be followed by applying an anti-chlor (sodium bisulfite or sodium hydrosulfite).

Potassium Permanganate

1. Strongest of all bleaching agents- dangerous on most fibers and dyestuffs!

2. Sold in liquid form

3. Generally used on the spotting board

4. Can be diluted for restorations. Test for colorfastness of fabric before using.

5. Alkaline by nature- accelerated by acids.

6. May cause brown discolorations that can be corrected by applying

hydrogen peroxide.

Reducing Bleaches

Sodium Bisulfite

1. Is sold in powdered form as a mild reducing bleach.

2. Use 1-2 ounces per gallon of water

3. Can be used as an anti-chlor.

4. Can be used as a mild whitening agent.

5. Can be used on the board for the removal of some tannin stains that contain sugars, dyes and inks

6. While used primarily as a bath bleach, it can also be used on the board

Sodium Hydrosulfite

1. Is sold in powdered form under different trade names

2. Used for the removal of dyes and fugitive prints, as well as some oxidized tannin stains.

3. Can be used as a whitening agent

4. Used primarily as a bath bleach (1-2 ounces per gallon of water.

5. Can be used as a bleach on the spotting board.

6. Acid by nature, accelerated by acids.

7. Should never come into contact with metal tubs, metal garment trimmings, or fabrics that contain metals or metallic coatings.

8. Safe on most fabrics, unsafe on most dyestuffs.

Titanium Sulfate

1. Used to remove dye stains

2. Primarily used as a spotting board bleach

3. Cannot be used as a whitening agent

4. Never use with an alkali- can cause permanent discolorations.

5. Is a blue-black liquid sold by various manufacturers?

6. Is acid by nature and will become more aggressive when acids are applied.

7. Dilute in accordance with the manufacturer’s instructions.

8. Safe on most fabrics, unsafe on most dyes.

9. Rust remover will often correct discolorations caused by alkali, chemical reactions with other bleaches and metals.





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