Everything You Need to Know About Ammonium Thioglycolate Relaxers
If you've ever sat in a salon chair for a relaxer treatment, you've likely experienced the work of ammonium thioglycolate — even if you didn't know it at the time. This chemical is the backbone of virtually every lye and no-lye relaxer on the market, and understanding how it works is essential if you're studying cosmetology, working in hair care, or just curious about what's happening to your hair during a chemical straightening process.
Here's the thing — there's a lot of confusion around these chemicals. People mix up how they work, what they do to the hair shaft, and what makes one type different from another. So let's clear it up.
What Is Ammonium Thioglycolate?
Ammonium thioglycolate (often abbreviated as ATG) is a reducing agent — a chemical that breaks disulfide bonds in hair. It's the active ingredient in most chemical hair relaxers, and it's what actually straightens curly or wavy hair.
Let me back up for a second. Your hair is held together by two types of bonds: hydrogen bonds (which are weak and break easily with water or heat) and disulfide bonds (which are strong and determine your hair's fundamental shape). Curl pattern? That's your disulfide bonds at work. They're what make curly hair curly, and they're incredibly tough to break.
That's where ammonium thioglycolate comes in Simple, but easy to overlook..
ATG works by reducing those disulfide bonds — essentially breaking them apart so the hair can be reshaped. Once those bonds are broken, the hair becomes pliable enough to be straightened. When the chemical is applied, it penetrates the hair shaft and chemically alters the cysteine residues (the amino acids that form disulfide bonds). A neutralizer then re-forms the bonds in the new, straight position.
The Chemistry Behind It
The ammonium thioglycolate molecule contains a thiol group (-SH), which is what gives it its reducing power. When it encounters the disulfide bonds in hair, a reduction reaction occurs:
S-S bonds (disulfide) → 2 -SH groups (thiol)
This breaks the cross-links that give hair its curly or wavy structure. The hair is then physically straightened while in this weakened state, and a neutralizing agent (usually hydrogen peroxide or sodium bromate) re-oxidizes the bonds in their new configuration Most people skip this — try not to..
It's why relaxers are permanent — you're not just temporarily masking the curl like you would with heat styling. You're actually chemically altering the hair's structure at a molecular level It's one of those things that adds up..
Why This Matters
If you're studying for a cosmetology exam, understanding ammonium thioglycolate isn't optional — it's fundamental. You'll encounter questions about how these chemicals work, what they do to the hair shaft, and what precautions to take when using them.
But it matters beyond the exam room, too. Plus, misusing these chemicals is what leads to hair breakage, scalp burns, and long-term damage. When you understand the chemistry, you understand why timing matters, why sectioning the hair matters, why the neutralizer is non-negotiable The details matter here..
Here's what most people miss: the strength of the relaxer depends on the concentration of ammonium thioglycolate. Higher concentrations break bonds faster and more completely, which means faster straightening — but also more potential for damage if left on too long. This is why professional products are formulated with such precision, and why DIY relaxers are so risky.
How Ammonium Thioglycolate Relaxers Work
The process isn't complicated, but it has several critical steps that must be followed in order.
Step 1: Preparation
The hair should be clean, dry, and properly sectioned. Plus, most stylists apply a protective barrier along the hairline to prevent scalp irritation. The hair is typically divided into four to eight sections depending on thickness and length Turns out it matters..
Step 2: Application
The relaxer cream is applied to each section, starting at the back of the head (where hair is typically most resistant) and working toward the front. The application technique matters — you want to coat the hair shaft evenly without overlapping previously treated sections.
Step 3: Processing
This is where the ammonium thioglycolate does its work. Processing time varies based on the hair's texture, the desired level of straightening, and the specific product used. Now, this is also where things can go wrong fast. Leaving the chemical on too long leads to over-processing and breakage.
Step 4: Rinsing
The relaxer must be completely rinsed from the hair before moving to the next step. This usually takes several minutes of thorough rinsing.
Step 5: Neutralization
The neutralizer stops the chemical process and re-forms the disulfide bonds in their new straight configuration. This step is absolutely critical — skip it, and the hair remains chemically unstable and prone to damage Took long enough..
Step 6: Conditioning
Deep conditioning is essential after any chemical service. The relaxer process is harsh on the hair cuticle, and conditioning helps restore moisture and elasticity But it adds up..
Common Mistakes and What People Get Wrong
There's a lot of misinformation floating around about relaxers. Here's what trips people up most often Not complicated — just consistent..
Thinking "no-lye" means "chemical-free." This is probably the biggest misconception. No-lye relaxers still use ammonium thioglycolate — they just use a different alkalizing agent (usually calcium hydroxide or lithium hydroxide) instead of sodium hydroxide (lye). The end result is the same chemical process on the hair.
Believing relaxers only affect the outside of the hair. The disulfide bonds that ATG breaks are located throughout the hair shaft, not just on the surface. That's why relaxers change the hair's fundamental structure rather than just smoothing the cuticle And it works..
Overlapping relaxer on previously relaxed hair. When you apply relaxer to hair that's already been chemically treated, you're essentially double-processing it. This is one of the most common causes of severe damage and breakage.
Skipping the neutralizer. Some people think they can skip the neutralizer if they want softer results. In reality, skipping this step leaves the hair in a chemically unstable state. The disulfide bonds haven't been re-formed, so the hair is weakened and will break easily.
Assuming longer processing time = better results. More time does not equal straighter hair once the bonds have been broken. After that point, you're just damaging the hair. Always follow the manufacturer's recommended processing time.
Practical Tips for Working With Ammonium Thioglycolate Relaxers
If you're a stylist or student, these are the things that actually matter in practice Easy to understand, harder to ignore..
Always do a strand test first. This tells you how the hair will respond and helps you gauge processing time. It's non-negotiable for any chemical service.
Never relax dirty hair. Hair should be clean but not freshly conditioned — the conditioning products can create a barrier that prevents the relaxer from penetrating properly.
Watch the clock, not the curl. The hair won't look straight while the relaxer is processing. Checking constantly and leaving it on "until it looks right" is a recipe for over-processing Small thing, real impact..
Use a protein treatment afterward. The chemical process depletes the hair's natural protein. A protein treatment helps restore strength The details matter here..
Space out your services. If you're relaxing hair that's already been chemically treated, wait at least six to eight weeks between services. More if the hair shows any signs of damage Easy to understand, harder to ignore. That's the whole idea..
Frequently Asked Questions
Can ammonium thioglycolate be used on all hair types?
It's most commonly used on Type 3 (curly) and Type 4 (coily) hair, but it can be used on any hair type that needs chemical straightening. The concentration and processing time will vary based on the hair's texture and condition.
Is ammonium thioglycolate the same as thioglycolic acid?
Not exactly. Day to day, thioglycolic acid is the acid form, while ammonium thioglycolate is the ammonium salt. In relaxers, the ammonium version is used because it's more stable and effective in the alkaline environment needed for the process That's the whole idea..
Why do some relaxers burn during processing?
A slight tingling is normal, but burning indicates the chemical is contacting the scalp. This can happen if the product is applied too close to the scalp or if it's been left on too long. Always use a protective barrier along the hairline and never apply directly to the scalp Less friction, more output..
Can you reverse a relaxer?
Once the disulfide bonds have been broken and re-formed in a straight position, the process is permanent. The only way to return to a curly state is to cut off the relaxed hair or use a texturizer/curl former to re-break the bonds into a new pattern.
The bottom line is this: ammonium thioglycolate is a powerful chemical that does exactly what it claims — it breaks the bonds that hold your hair in its natural curl pattern and allows it to be reshaped. When used correctly by someone who understands the chemistry, the results can be beautiful. When misused, the damage can be severe and sometimes irreversible.
If you're studying for an exam, focus on understanding the actual chemical process — how the reduction works, what the neutralizer does, and why timing matters so much. The questions you'll encounter will test whether you understand the science, not just the procedure.
