Straighten New Hair

Glatt by Schwarzkopf
Q: I am planning on buying Glatt chemical straightener and chemically straighten my hair myself.
Once new hair starts growing back in, can I reapply the chemical straightener to my whole head or am I supposed to just apply it to the new hair growth?

A: This product, by the Schwarzkopf Company is listed as a "permanent straightener" and specifically warns against use with metallic combs and tools and is warned against use on hair that has been previously straightened with Lye-based products or hair colored with metallic dyes. This indicates the same kinds of concerns as are found with traditional "relaxers" and in fact, the product has similar directions.
In fact, the instructions from the product packaging clearly states that the product should be applied only to the "curly new growth" of the hair on subsequent applications. This with the warning against use on previously straightened hair (with lye-based products) makes for solid verification that it is not something to be applied to hair that has been previously straightened with this product.
Do be sure to perform a patch test (skin test) prior to applying this on the scalp. There could be a serious reaction if you are sensitive to the ingredients of the product, so be safe and test it beforehand.
See also:
Permanent hair straightening
What is the difference between a traditional relaxer, Japanese straightening and Brazilian straightening?