Relaxer Strengths

How They Differ and When to Use Them

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Permanent creme relaxers are commonly manufactured in a variety of strengths, typically mild, normal and super (also called resistant). The real difference between the various strengths is the amount of active ingredient (straightening agent) they contain. Sodium hydroxide, guanidine hydroxide, potassium hydroxide lithium hydroxide have all been used in relaxers as active straightening agents, however, the first two have proven to be the most effective. 

Mild formula relaxers contain less of a given active ingredient than either normal or super strengths. For instance, in the case of sodium hydroxide relaxer, the mild strength may contain 1.85 to 2.00 percent concentration of sodium hydroxide, 2.06 to 2.20 percent for normal and 2.25 to 2.40 percent for super/resistant. The balance of the relaxer formula is a blend of oils, water and emulsions that provide an easy-to-apply medium for the active ingredient and that work to protect the scalp from irritation. The active ingredients in relaxers straighten by changing a third of the hair's cystine bonds into lanthionine bonds. The concentration of the active ingredient determines the rate at which the bonds are changed. That is, a mild strength relaxer will lanthionize a fewer number of bonds within a certain period of time than will normal or super strength. 

Fine, not-so-excessively curly hair has fewer bonds overall than does coarser, excessively curly hair. Therefore, to lanthionize a third of the bonds (the minimum required to effectively relax the hair), it will take a shorter period of time for fine hair than for either medium or coarse hair. Thus, if only one strength was made available in the marketplace, say for example normal, one of these two undesirable circumstances would occur:

1. The processing of fine hair would take place too rapidly, giving the stylist inadequate time to properly apply and smooth the relaxer. Overprocessing would result.

2. The processing time, to adequately straighten coarse hair, would have to be extended, leaving the product on the hair and scalp so long that irritation would become a problem for many clients. 

The reason why various strengths are widely available by manufacturers is to accomplish these three objectives simultaneously:

1. Provide effective straightening. 

2. Minimize exposure of clients' hair and scalp to the highly alkaline active ingredients. 

3. Provide the professional stylist enough time to apply the relaxer and smooth it throughout the entire head of hair. 

Experienced stylists recognize that different relaxer brands may process faster than others, even though the strength is the same. This is not necessarily because a higher concentration of the active ingredient is in one brand versus the other. Often, manufacturers formulate their relaxers purposely to process at a particular rate, sometimes because they wish to compete among similar, highly accepted brands on the market or because of feedback from stylists in preliminary salon tests. In any case, processing time can be slowed by altering the formula's oil and water ration, without regard to the amount of active ingredient. The more oil a relaxer emulsion contains, the slower the processing pace. Hair care chemists, however, are always mindful that increasing the amount of oil in a formulation also increases the chances of product separation. 

Many stylists work very quickly and effectively with relaxers and tend to prefer faster-worker formulas. Some stylists, however, need a little more time than others for thorough application and complete smoothing. These stylists should look especially for a control formula relaxer that has a built-in time release mechanism that discharges equal quanta of the active ingredient at equal time intervals. 



A Word About Guanidine Hydroxide (No Lye) Relaxers

This type of relaxer is preferred by many stylists and clients alike, because of its low potential for scalp irritation. Unlike sodium hydroxide relaxers, the active ingredient is not pre-blended into the creme relaxer. Rather, the guanidine hydroxide is prepared in situ by mixing liquid activator containing guanidine carbonate calcium hydroxide that is the active straightening ingredient. The calcium hydroxide within the mixture is ultimately changed into an inert material called calcium carbonate that rinses away during the rinsing process. 

While this type of relaxer is commonly available in one strength, it can be adjusted by regulating the amount of activator mixed into the creme relaxer. Since different brands are formulated differently, the manufacturer must be consulted before you will know precisely how to accomplish this. The fact remains however, that the amount of activator will determine how fast the relaxer will process, and you may achieve a mild or normal strength by mixing only a portion of the activator provided.

I'm often asked by professional cosmetologists, "Why is this type of relaxer only available in two parts?" The reason is that guanidine hydroxide is not chemically stable in the presence of water that is a key ingredient in the creme relaxer. Therefore, guanidine hydroxide must be chemically created from the guanidine carbonate (in the activator) and calcium hydroxide (in the relaxer creme) by combining them just prior to use. Once mixed, the relaxer must be used within 12 hours, otherwise, it would change to ammonia an area that swells hair excessively, causing damage to the hair. 


Selecting the Appropriate Relaxer Strength 

Each client should be properly assessed before a relaxer strength is selected. The texture and condition of the hair will determine which is best. When scalp comfort is a concern, use a sensitive scalp formula relaxer, adjusted for the strength desired. 


Mild Strength 

Mild strength relaxers should be used on fine, delicate or color-treated hair or if hair is porous or somewhat weak. A strand test is highly recommended in this case. Many relaxer brands note that 13 minutes is the maximum amount of time for both applying and smoothing fine, delicate or color-treated hair. However, color-treated and over-processed hair process at a very rapid pace, so the stylist must be able to "read" the hair and determine when proper straightening is achieved, even if the time limit has not expired. 


Normal Strength 

For medium textured hair, in generally good condition, a normal strength relaxer is recommended. Most African American hair textures fall within this category. It takes approximately 15 minutes with most brands to process the hair using normal strength, and this time limit includes both application and smoothing times. 


Super/Resistant Strength 

Super or resistant strength relaxer formulas are appropriate for coarse hair textures and for resistant hair. (Resistant hair is any texture that cannot be adequately straightened with mild or normal strengths. Resistant hair may or may not be excessively curly. For instance, gray hair is often resistant, as is some naturally wavy hair. Some clients may have hair that is wiry or that has a relatively large hair strand diameter. These hair types also tend to be resistant, even though they may not be tight textured). Coarse, resistant hair is usually processed up to 18 minutes using a super-strength formula.