Educators say nearly 90 percent of younger stylists have never done a chemical service beyond hair color since they left beauty school. But even seasoned pros have seen a chemical skills' erosion, thanks to the "use it or lose it" factor. This means all stylists could benefit from a refresher in how to safely combine multiple chemical services. It all comes down to the hair's condition, the chemicals used and the operator's acumen. 

Condition First

Whatever chemical service you're performing, porosity and elasticity tests are musts because the biggest issue is the hair's integrity. Even the most accomplished chemical specialists perform a strand test on previously sensitized hair before coloring.

"Poor elasticity and poor porosity go hand in hand," says Steve Sturman, owner of Transformations in Middletown, New York, and a chemical specialist/educator. "After any chemical texturizing service, we check the hair for color-suitability with the sink-or-swim test. Snip a piece of damaged hair, put it in water and wait a few seconds. If it floats, you can color; if it sinks, it's too porous and will absorb color too quickly." Also, be sure to analyze the scalp for signs of irritation prior to any chemical combo.

If you are seeing a new client who has relaxed hair and now wants color, establish a thorough written history, perform a complete hair and scalp analysis and take extra precautions with deep conditioning.

The most common mistakes, says Sturman, include failure to perform a proper strand test for degree of straightening or curl pattern, leaving too much space between perming tools (unless the wrap is a condensed one) and improper rinsing. Leave too much of any thio-based product on the hair and add a neutralizer, and the peroxide in the neutralizer will cause a heat reaction that both dries and lightens the hair.

Before you consider combining chemicals, start with this refresher:

Going Straight

Today, straightening and smoothing chemicals fall into three groups: Traditional sodium relaxers; ammonium thioglycolate or thio-based straighteners, used in services like Japanese Thermal Straightening or Reconditioning; and Keratin-based straightening "treatments."

Relaxers that contain sodium hydroxide work for anyone with curl. Their "no lye," high-alkaline relatives-potassium, lithium or calcium hydroxide, or guanidine carbonate-are for clients who are sensitive to sodium hydroxide. The percent of sodium hydroxide and the pH determine the product's strength. The higher the pH, the faster it will act. As a rule of thumb, use a mild-strength product for fine or permanently colored hair; a medium-strength product for most medium-textured hair and super-strength for extremely resistant hair.

Hair that's been relaxed with one of the hydroxide-family products has permanently straight bonds and cannot be exposed to any thio-based product.

A few musts to follow:

• Don't relax hair that's bleached or colored with metallic dyes.

• Select a product with the right strength for the curl configuration.

• Always base the scalp and hairline and protect previously relaxed hair. 

• Work systematically, in sections, smoothing on the product. Then smooth the product with the back of the comb. Avoid relaxing the hair 100 percent-leave some body.

• Work fast-the average relaxing service takes less than 15 minutes.

After relaxing the hair, it's important to remove all the product. Use a neutralizing shampoo followed with a pH-balancing treatment and a conditioning service. Moisture and protein rebalancing keeps relaxed hair healthy.

You can use demi- or semipermanent color  the same day as a relaxing service, but wait two weeks before using permanent color. For a client who wants both services, apply the relaxer first because it will lighten color-treated hair.

New Alternatives

Some straighteners rely on old perming chemicals. They use thio to break the hair's disulfide bonds plus mechanical straightening. The bonds rearrange themselves in a straight configuration reinforced with flatironing. Then, a neutralizer secures the bonds in their new formation. Thio-based straighteners should never be used on hair that's been exposed to a sodium relaxer, or one if its relatives.

When should you use a "traditional" relaxer and when should you choose a
thio-based product? For super-curly and classic African-American textures, traditional products are the best choice. 

Depending on the curl configuration, thio-based products are for clients who want everything from frizz-reduction to curl-control to smooth, straight locks. Their natural texture can range from straight to moderately curly.

When coloring hair that's been exposed to thio-based products, avoid same-day, permanent-color services, lest you lighten the hair.

"Normally, same-day semi- or demipermanent color services create little problem," says Sturman. "However, if you just used a chemical texturizer and the color product relies on progressive dyes, leaving it on too long will cause the hair to be too dark. The color will take faster with any same-day service, due to increased porosity."

Recently,  "Brazilian" straighteners have been in the media. Many contain formaldehyde at controversial levels. In response, several companies have now launched formaldehyde-free keratin straightening treatments. They rely on the concept that curly hair has less keratin than straight hair. Add keratin, seal it in with flatironing and various polymers, and the hair stays straight. Because these products do not use thio or lye, chemical incompatibility is not an issue.

 Theoretically, this allows you to use them on previously sensitized hair, or even apply color the same day as the keratin treatment. However, the hair's moisture-protein balance must be kept in mind. Keratin is protein, and an overabundance of protein can make hair hard and brittle.

Chemical Curling and Retexturizing

Forming curls chemically is a less permanent proposition than straightening services. Whether you use a traditional thio-based (acid or alkaline) or a cysteine (amino acid) texturizer to create curl, the hair's bonds are broken. They reform around a particular tool, chosen by diameter or shape for the desired final result. Today, rag and Velcro rollers provide the soft, loose look clients want.

No matter the chemical type, less than 100-percent bond reformation can result in weakened or damaged hair. Also, thio requires swelling the cuticle, which abrades it and can cause dryness. Eventually, the curls relax.

When used correctly, some of the newer texturizers swell the cuticle far less than traditional ones. Because they have an ionic attraction to the cortex, they allow superior bond reformation. They also use a narrow pH of 8 to 8.3, which is gentle on hair and allows better recovery. Other modern texturizers rely on bisulfite, an inorganic, simple salt that works at a pH of 6.5 to 7.5. It's the weakest and mildest of reducing agents, used in a semipermanent or temporary texturizing service.

Combining Chemicals

It can't be stressed enough: Performing permanent color and chemical texturizing services on the same day is not ideal. When the client wants both, semi- and demipermanent products are the safest options.

Permanent color can be used two weeks after a relaxer re-touch and about three weeks after a virgin relaxer service. Wait at least two weeks after a thio-based service before using permanent color. In either case, perform a hair and scalp analysis, repeating the tests for porosity and elasticity. Your safety net: a strand test.

When choosing a texturizer, remember:

• Acid waves have a pH below 7 and swell minimally, so they're gentler on porous hair. They require both heat and mechanical tension.

• Alkaline or "cold" waves have a pH of about 9 and don't use heat. They swell the hair shaft to create tension and are for normal-to-resistant hair and wraps that use less tension, like most modern ones.

• Low pH alkaline waves are buffered to reduce swelling. They're best for color-treated hair, can be used with any wrap, require no heat and process quickly.

• Exothermic waves are self-heating and self-timing. They use hydrogen peroxide to create a chemical reaction, and are used for over-processed hair.