EDITED WITH UPDATE, PLUS ADDED PHOTOS:
Jan 11, 2023 - it took over 3 months for the super-flat-&-super-straight texture to settle back to anything resembling my natural curly-wavy hair texture. Let's just say my face is 'fluffy' so the volume from my natural hair texture was more proportionate a style for my face. AFTER 3 OR 4 MONTHS I ended up cutting off nearly all of my hair, th sedimentary had been keratin straightened - not because I hated it, but because I became completely obsessed with the modern mullet!

Re: washing - washing did not significantly alter my hair, it remained very straight and very shiny through many washes over 3 (maybe 4?) MONTHS. Fog was not an issue at all, my hair stayed very straight in all of those situations when it normally would have reverted back to unruly curls (i.e. outdoor fog, or steam while cooking, or sweat from exercise). So I'll say the product and treatment are very long lasting.

The ends did feel a little dry, like the keratin treatment closed off my hair from absorbing any of the deep conditioners I typically apply throughout the month. Beyond that, I don't have complaints about the product or how it changed my hair.
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March 4, 2021 - I've always been a DIY-er, and I have fine, 2b/2c curls, below-shoulder-length hair that tends to be quite frizzy when allowed to do its own thing -- especially when I travel to more-humid parts of the country. I've found if I blow-style my hair straight, with a large round brush, I can go a full week without needing to wash/ re-style -- but there's always the risk that if it's a muggy, foggy, or rainy day, I've got problems. I stumbled across this product, watched several videos & reviews, and decided to give it a go. I followed the directions to a T, and found the application techniques that Eliana Jalali showed in her video (uploaded here to the product) extremely helpful.

The results are that my hair is VERY smooth, and VERY straight... maybe too straight? What I mean by that is before doing this treatment, when I just blow-style straight, it still has plenty of body; whereas right now it's quite flat, but shiny straight. That's why I rated 4/5 stars. As of today, I haven't washed & styled since doing the process 5 days ago, so I'll update my review once I've done a couple washes & see how it fares.

A few notes/ observations:

1) I did this treatment 2 days after coloring, and it definitely lightened the color, probably a full shade or slightly more. My thought process for doing things in that order was that I was concerned that if I did the keratin treatment first, and colored afterwards, the color might not "take" as well. I plan to research this more. But either way, it would be an easy adjustment to color slightly darker than intended, then do the keratin.

2) As mentioned, my hair is slightly-below-shoulder length, but I have a less-than-average amount of hair, and what I have is moderately fine. I will easily get 2 uses out of this first package -- possibly even 3 if I find a good clarifying shampoo (I used a lot prior to applying the keratin). But if you have thick hair, or a lot of hair, or very long hair, you'll probably only get 1 or 2 uses.

3) Do not underestimate the fumes, while they're not horrid, they're definitely fairly irritating. I really needed my wall-mounted/ large mirror in my bathroom to feel like I could see all angles of my head -- utilizing the two adjacent medicine cabinet doors, I can see the back fully, leaving my hands free for the process. But my bathroom is in the center of my house, with no nearby windows, and the fan is only in the shower area. That became a bit of a problem, as my eyes began to water and my nose began to run. I finally pulled out a small fan & set it on the counter, on low to blow away the fumes, but if I continue using this, I'll need to figure out something near a window I can open.

4) I opted not to use gloves this first time around, most (all?) of the videos I watched, the demonstrators didn't. And I'm guessing I'm like a lot of people, when I straight iron my hair, it's a two-handed process... meaning I hold the iron in my right hand, and handle my hair with my left. Which means my left palm & fingers got a thorough coating of the product, AND, in handling my heated hair now & then, the keratin actually bonded to my left palm & fingers, whoops! That took a solid 5 days to wear off, even with washing my hands constantly during this pandemic. It was totally invisible, and really nothing more than an annoying feeling, but I mention it so you can make an informed choice on whether you want to wear the gloves.

This definitely is a 2 person process. My daughter helped me apply the product according to directions. She flat ironed all the pieces until straight. The directions told us to go over each section 8-10 times at root and 4-6 at ends. She didn't do that - and I think that is the reason my hair isn't completely straight now (and the reason I gave 4 instead of 5 stars). My hair has a slight wave and some frizz still, but I believe this is our fault. It IS much easier and quicker to dry it now. I use the flat iron to quickly remove the last waves and frizz and then I'm good fit the day. The product has a somewhat pleasant issue to start, but as it really gets into your nasal passages it starts to bother you. It's not terrible, but if you can, wear a mask to prolong this from happening.

I have frizzy/ curly and bleached hair, I did this treatment 20 days after a bleach session and it works so well, I can rough dry it and it looks like I straightened it. Only draw back is that it kinda burns the eyes but it's worth it

So before I go into my review of this product, let me give you the stats on my hair because I think depending on the type of hair you have, this product might work differently for you OR you should have different expectations for the end result. I'm Caucasian in my late-30's and have chin-length, color-treated hair. My hair is course and thick and has a lot of gray in it. It is also curly/wavy..and not in a good way. If I let it air dry, it's very frizzy with some wave and curl. I spend about 20-25 minutes daily drying and straightening it in sections.

I had two goals for this product- first was to decrease the amount of time I spent drying and straightening my hair daily or even- gasp- let it air dry and not look like a cavewoman. Secondly, my husband and I are going on a trip overseas and I didn't want to deal with my hair then. After doing my research on the different treatments, I chose this one after seeing someone use it on a youtube video. What I liked about this product was that, unlike a lot of other products on the market, it says you can WASH and style your hair right away after use. Many products make you wait 3 days to wash your hair and I am just not down with that.

I found this product to be easy to use. I did not notice any strong odors- if anything, it smells very fruity. You do have to follow the directions carefully, but once you do this treatment, each subsequent treatment should go faster. I had my sister come over and apply it and do the straightening because my hair is on the shorter side and I wanted to make sure all of my hair got good coverage and was flat ironed properly. It took maybe an hour and a half total, but like I said, I think it will go faster next time as we won't need to stop and read directions. Not that the directions are complicated, but there are a few important steps you don't want to mess up. My sister found it helpful to use a hair color applying brush to apply the treatment and then use a comb to pull it through.

I will admit that before I washed the treatment out and used the repair mask, my hair was very heavy. Almost a little sticky, but not quite. But I figured I really had nothing to lose. Back to my hair type and expectations- since my hair is thick and course, I was not expecting my hair to look like the model in the picture- baby fine and silky. I really just wanted to decrease my frizz and the time it takes to dry it in the morning.

Results:
I LOVE this product. It's been almost a week and I've tried out a few different things to see how well this product has worked. First, I dried it with a round brush without sectioning and without using a flat iron. Then I sectioned it and dried it without the flat iron. (See a theme here? No flat ironing!) and I have been REALLY impressed by how tame my hair is and how little frizz there is. After drying it with a round brush in sections and not flat ironing it, it looks as good or better as when I was doing that AND flat ironing. Now the real test: We had some snow days here and I knew I wouldn't be leaving the house, so I let my hair air dry. This in the past has been a disaster- like I don't want anyone to see my hair that way ever. I am happy to report that my hair looks GREAT just with air drying it! I do think I like it better drying it with a round brush to give it some definition at the ends, but that's personal preference and due to the fact that my hair is on the shorter side. If my hair was longer, it would be perfectly fine. I love the fact that my hair is not being damaged daily by the hair dryer and flat iron as I'm trying to let my hair grow out.

With my chin-length, thick hair, I probably used 1/3 of the treatment, so this is a very good value!

If I had one tip for this treatment, it would be to have a second person applying and straightening the hair simply to ensure the product is evenly applied and the back of the head gets straightened well.

Awesome, awesome, awesome product.

Let me start off by saying that this is my first keratin smoothing treatment, either at home or professionally. I'm a total weirdo with researching products before I buy them and kind of a home beauty junkie. I probably invested a good 2 hours scouring the internet making sure that I was getting the best deal and the best product. I'm extremely happy that I ended up ordering this!!!!

I have hair that has been badly damaged by years of bleaching, dying, straightening, and other heat application. I recently made the decision to try to go almost completely heat and bleach free and to wash my hair less so that I can give it time to heal and grow properly. Before I started using this product, I had been setting my hair every few days with curlformers (overnight curlers that work wonders.. you should check those out too) to smooth out my hair and give it a style that worked professionally. Left alone, my hair is frizzy, poofy, and wavy.. just kind of a goofy texture. I will link pictures for the before and after. (It had been set in braids or something in the before one but is still a pretty accurate representation. I couldn't find an unaltered before one because I never took pictures with it without fixing it).

The actual processing of the product wasn't a walk in the park, but was nothing impossible. Takes a little over an hour, with directions included in the kit. They give you a clarifying shampoo, the actual straightening product (the bread and butter of the product), and a mask. I used a regular shampoo before the clarifying shampoo (washed it twice). The worst part about it was the fumes during the actual straightening process. You may want to use an older or backup straightener if you have one, though I did not notice any residue on mine. Make sure that you do this in a large room (I ended up moving from my small bathroom to my larger bathroom) so that the fumes are less of an issue. I ended up closing the eye on the side of the head where I was straightening. Goggles probably wouldn't be a bad idea. I would also recommend not having kids or pets in the room if you have any of those. It is definitely unpleasant, but if you get that smell you will know that you are doing it correctly. I then used the mask and then my regular conditioning treatment.

I could feel my hair sitting flatter in the shower. I let it air dry so that I could see the full results. They were great! It looked better than if I had straightened it, and my hair is so shiny. It also helps your hair to lay better with extensions if you use those. However, I would not recommend using this if you like the look of big hair all of the time. It might smooth it out too much for you. Anyway, it's been about two weeks since I've used it and the results are still about the same. I'm going to try to hold out as long as I can before I use it again because I don't like the idea of the iron that hot on my hair, but it definitely beats having to straighten it every day, so it saves your hair in the long run. You might have to do a few touch up spots in the morning if you like it super straight, but that's it. I'm not sure why more people do not use this product!! Saving me money in the long run, and a huge chunk of my morning. Hope you like it! I have not been paid or received a discount for writing this review, just really liked it and wanted to share.

Last thing, the company originally sent me the smaller bottles that sell for 55 on here (1.4 oz?) I messaged them and they were very nice. They let me keep the smaller ones, as well as overnighting the bigger ones the next day. Just make sure that they send you the right size (big bottles about the size of normal shampoo and conditioner).

:)

EDIT: one month later and still no damage. Hair is still pretty straight.. I might touch it up soon.