Smoothing System I or II? Choose by hair thickness
8 min read Care know-how Updated 5 October 2026 By Anna Sophie Schulenburg
Smoothing System I is MONAT's anti-frizz care for fine to medium hair, Smoothing System II the one for medium to thick hair. Before you order, rub a strand from the nape of your neck between your thumb and forefinger. If it turns silky and flat, choose System I; if you can feel individual firm hairs, choose System II. If the result sits somewhere in between, start with System I when your roots already go flat by the evening of wash day. After three to four washes, check your roots and lengths to see whether the weight is right.
Frizz happens when the outer cuticle layer of the hair doesn't lie flat and the fibre takes up moisture from the air unevenly. Individual hairs then swell to different degrees and stick out of your style, most visibly in the rain, in bathroom steam or in muggy weather. Both systems care for this surface at every wash. They differ in weight. System I is lighter, so fine hair keeps its movement. System II is richer and made for thick, unruly hair.
Smoothing System I or II: compared by hair thickness
| System I | System II | |
|---|---|---|
| Hair thickness | fine to medium | medium to thick |
| Weight of the care | light | rich |
| Typical hair | soft, falls flat quickly, looks greasy at the roots sooner | dense with plenty of grip, sticks out, puffs up in humidity |
| Switch if | the lengths stay rough and puffy even though the roots are fully dry → System II | the roots lie flat by the evening of wash day and get greasy sooner → System I |
| Not for | curls you want to keep | fine hair; curls you want to keep |
How to tell your hair thickness: the thumb and forefinger test
Hair thickness means the diameter of a single hair. How many hairs you have is a different question. Lots of fine hair looks dense and still goes flat under rich care just as fast as a little fine hair. That is why diameter comes first when you choose between System I and II.
For the strand test, take a pencil-thick strand at the nape and rub it between your thumb and forefinger. For the single-hair test, roll a shed hair between the same two fingers. Take one hair each from the crown, the back of the head and the temple, because hair at the temples often grows finer, and go with what two of the three samples say. Do both tests the day after washing, with no spray, cream or oil in your hair. Styling products make every hair feel coarser.
| What you feel | Hair thickness | Version |
|---|---|---|
| You can barely feel the single hair between your fingers. The strand feels silky and goes flat. | fine | System I |
| You feel the hair as a thin, smooth thread. The strand has some grip but gives. | medium | Borderline, see next section |
| You feel the single hair clearly, almost like wire. In the strand you can feel individual hairs, and it stays firm. | thick | System II |
Landed in the middle row, or did the two tests give different answers? The free hair analysis asks about hair thickness, roots and lengths and suggests one of the two versions.
Medium hair: how to settle the borderline case
Medium hair suits both systems. Then everyday observations decide, and you need no new product to make them. Go through the questions in order and stop at the first yes.
- Do your roots already lie flat by the evening of wash day, or get greasy on day two? Then System I, because any extra care near the roots makes this problem bigger.
- Do your lengths stay rough and puff up after blow-drying, even though you dried right down to the roots? Then System II.
- Neither applies? Then start with System I. If it's too light, add a mask once a week. Too much weight, on the other hand, only comes out again with a smaller amount or a switch.
System I, System II or neither
Reach for System I if your individual hair is fine, your roots fall flat quickly or you mostly wear your hair down and with movement. Medium hair that gets greasy on day two is also better off here.
System II suits you if your hair is thick and dense, sticks out after blow-drying and puffs up at the first hint of humidity even with the right technique. Thick hair usually takes the richer care without the roots lying flat by evening.
Neither is right if you want to define and keep waves or curls. Smoothing care works against their shape, and a wash day with Curl Perfection relies on definition and moisture. If your hair snaps when you comb it or you see white dots on the ends, the frizz usually has damage to the fibre behind it. Then bond care for brittle hair comes before any smoothing routine, and split ends get cut, because no care sticks them back together.
If your lengths are mainly dry and barely frizzy, a moisture base is the closer fit. The comparison of MONAT systems by main goal and hair thickness puts Advanced Hydration and Renew™ next to the Smoothing line.
If your hair only frizzes on the odd humid day, you may not need a new system at all. Often it's enough to fix the most common causes of frizz: a towel you rub with, a hairdryer on its highest setting or hair that leaves the house half dry.
How to use the Smoothing System
Step 1 — Wash. Shampoo goes on the scalp only, with lukewarm water. For chin-length hair a hazelnut-sized amount is enough, for shoulder-length a walnut-sized one, lathered between your hands. With chest-length, thick hair, wash twice with the small amount rather than once with a lot. The lengths get cleaned as you rinse. Don't rub the ends against each other while you do, or you rough up the surface you want to smooth.
Step 2 — Condition. Squeeze the water out of your lengths and spread the Deep Conditioner from ear level through the lengths and ends: hazelnut-sized for chin length, walnut-sized for shoulder length. Detangle with your fingers or a wide-tooth comb as you go. Fine hair gets two minutes, thick hair three to five. Rinse the last few seconds a little cooler.
Step 3 — Dry. Press the water out with a microfibre towel or a T-shirt instead of rubbing. First spray a heat protectant made for hairdryers and straighteners into the lengths and comb it through. If the Smoothing Anti-Frizz™ Blow-Dry Spray is part of your routine, follow with three to four sprays for chin-length hair, five to six for shoulder-length and seven to eight for chest-length, half that for fine hair, and only on the lengths and ends. Blow-dry on a medium setting from about 15 cm away, nozzle pointing down in the direction of growth, until the roots are completely dry. With thick hair, divide it into four sections and pull each one smooth with a round brush, as when blow-drying without new frizz.
When System I is out of stock
Which products are sold as a set can change. If System I isn't available right now and your hair is fine to medium, buy the Smoothing Anti-Frizz™ Shampoo and the Smoothing Anti-Frizz™ Deep Conditioner separately and use them as a pair, with the amounts from the steps above. Switching to System II because it's in stock gives fine hair the very weight you were trying to avoid with your choice. Your consultant can tell you what is currently available.
What goes with the Smoothing System
If your lengths are dry as well as frizzy, swap the Deep Conditioner for the Super Moisture Masque once a week. Leave it on for five minutes, on fine hair only on the ends. A second shampoo or conditioner from another line alongside makes the routine hard to read, because after four weeks you no longer know which product made the difference. Blow-dry with the window open or in another room rather than in the still-steamy bathroom, so your hair takes up less moisture from the air while it dries.
After three to four washes: is the weight right?
The first wash tells you whether the amount is right. Whether the system is right only shows over several washes, in rain, in heated indoor air and with your usual styling. Correct the amount and technique first, and only switch systems if that changes nothing after two washes.
- Roots flat by the evening of wash day, hair gets greasy a day sooner → Deep Conditioner from ear level only and half the amount. If that doesn't help after two washes, move from System II to System I.
- Lengths rough after blow-drying, ends sticking out → leave the conditioner on a minute longer. If it stays that way, move from System I to System II.
- Frizz at the roots, lengths lie smooth → blow-dry the roots first and completely, because half-dry hair frizzes up again.
- Blow-dry spray sprayed right onto the scalp → lengths and ends only, half the amount for fine hair.
- Straightener over sections that still feel cool at the nape → finish blow-drying those sections first, because cool means still damp.
Quick questions
Does the Smoothing System straighten hair permanently like a keratin treatment?
No. A keratin or chemical straightening at the salon smooths the hair for weeks to months. The Smoothing System is care for every wash and doesn't change your hair's structure. Natural waves stay waves, and how smooth the result looks depends mostly on blow-drying.
Can I alternate System I and System II?
Rarely worth it. If you switch from wash to wash, after four weeks you won't know which weight did your hair good. Stay with one version for four weeks and then decide.
Do I need the blow-dry spray if I let my hair air-dry?
No. The blow-dry spray is meant for the hairdryer. For air-drying, shampoo and Deep Conditioner are enough, and you just press the lengths with a towel.
How often should I wash with the Smoothing System?
As often as before. Both systems are made for every wash, and how often you wash depends on your roots rather than on the product.
If you're torn between the two weights, the hair analysis sorts your answers on hair thickness and frizz and suggests the version to start with.