I am using these to restore 6mm white honeycomb subway tiles in our guest bathroom.Our grout is not very old and is just water-stained from a couple of years of showers. Because our tiles are so small, we have miles and miles and MILES of tiny "pieces" of grout. Scrubbing them individually with a toothbrush had helped marginally but nothing would restore them to a "clean" look without actual paint/recoloring of some kind.So the good news is, these pens work great if you are CAREFUL. The bad news is everything else.1) I have gone through 10 total pens so far. Our grout is very thin, very small and very rough, so the grout eats away at the pen's foam "nib" very quickly. Per the bottle itself, the applicator tip is "reversible" but having tried it, I can tell you that this is a complete joke as it is like replacing lead in a cheap mechanical pencil. If you take out the nib and try to flip it over, it will "slide" and tap back deep into the pen with even the slightest touch. Again, because our grout is rough, you HAVE to use a bit of pressure to get the color to soak in even working in repetitive even strokes, so once the nib is done, you might as well be done with the pen. I would much rather have had a super-fine and flexible "brush" to brush the product on, even if that meant the grout liquid was a bit drippy. I have a single sink, toilet and a tub/shower enclosure in the guest bathroom, my dad did the master and I understand from him he went through even more than I did. I am coming back to order more and I think all told I will probably end up around ~14 total pens used. There is a limit of 4 per order so just keep that in mind.2) Like some other reviewers have mentioned, you have to shake the pen to activate the paint material. Following the directions and shaking for 2 minutes, I did have 1 of the 10 pens thus far explode on me. It went EVERYWHERE - the ball bearing shot out of the pen like it was shot out of a cannon, EVEN THOUGH THE CAP HAD BEEN ON. Our green wall is now green and white, the shirt and shorts I was grouting in are ruined, and after that traumatic incident I did start shaking the rest of the pens while VERY TIGHTLY holding onto the cap. The paint really stains so I'm pretty much SOL, I will have to repaint that wall as my next project after I finish redoing the grout.3) The "quality" of the pens I received seemed highly variable. Most of the pens I received had a yellowish tannish foam applicator tip, which shreds easily and was one of the ones that exploded on me. Two of the pens I received had a white tip inside instead, and the quality was noticeably better and easier to use. The pen was much slower to "shred" the nib, and while it was a little more difficult to see if the paint had fully coated the applicator, the easy answer to that is to just press it until you see paint. If the manufacturer reads these reviews (ha), PLEASE USE THE OTHER MATERIAL IN YOUR PENS!We had a roof leak the caused newly grouted floors to be covered in orange runoff and left the white grout badly stained. Nothing worked until I tried Rejuvenate grout pens. Now the grout is pure white again and it’s instant gratification! I’m thrilled and it’s incredibly easy.It works, but the tip wears too fast and the ink is not enough to cover the area as described. I ran out of the tip and ink after 3-4 dozens of feet.After initial 2-minute shake followed by pressing the tip several times to prime, you need to keep pressure on the tip in order to let the ink come out through the tip consistently. Without pressing the tip slightly, ink will stop coming out. As a consequence, the tip wears very fast. Most grouts have grain and this tip won't last a few feet after being dragged on the existing grout.The product recommends to flip the tip when it's worn out, but the tip is already shortened leaving no tip even after flipping. That means flipping the tip is total non sense. See the photos of the tips after using 3-4 dozens of feet. There is no way one can use it after flipping the tip.I bought this to refresh the look of my kitchen counter tile grout which hasn't been redone since the house was built almost 40 years ago well before I first moved in. Now that I am preparing to sell and don't have the ability to rip everything out to start from scratch, with stains that bleaching pens simply won't fix in many areas of this grout needed something and I thought this product would be sufficient. It did work to some extent as the photo I have attached to my review will show. However, DO NOT accidentally or intentionally splash water on the area you use this, even 24 hours later, or your hard work with the easily frayed/splitting tip will be for nothing since that will make it come right off. The tip fraying issue is exacerbated by using the product where there are deep grout lines, you have to put a good amount of pressure on the tip against the surface - a light touch prevents the liquid from coming out no matter what angle you hold the pen in. Given the experience I had on my kitchen counters with accidental water splashing, I would suggest finding a different product for anyone hoping to use this in the bathroom. As for floor applications, there are likely better choices for that, which in my opinion you'll be happier if you search those out instead of wasting your money on a product that at best offers a substandard performance.The instructions say to shake with the cap on for 2 minutes, you don't really have to shake for that long, it doesn't do anything essential to the consistency or improve the application any more than you would if you just give it a minute of hard rapid shaking to ensure it's thoroughly mixed. My kitchen counters are a relatively small part of a 934 sqft condo, but took 2 pens for an only somewhat acceptable finished result. I will ultimately be going to one of the local big box home improvement stores to pick up a similar product for 'last minute' touch ups before any realtor showings - I just can't trust that it will last through my regular kitchen cleaning routine let alone wow potential buyers when the stuff wears/washes off so easily.The renewal is great, the tip/applicator is awful. Its basically useless after about a minute of work and it just gets messy. I got the job done, using a thin paintbrush and taking the thing apart. It wasn't too difficult but its getting two stars cause I also noticed home depot sells the exact same thing for 7$ also a two pack. Why are they charging more than double here?!there is a definite TECHNIQUE to using these effectively. I bought two packs and the tip of the first pen was obliterated so quickly. I was disappointed but not surprised as I had read the reviews. BUT by the third pen I had figured out the correct pressure and speed and the pen worked like a dream! When the pen felt dry I would prime it a few times and the paint would start to flow again. I am happy with the results!I used this to touch up stained grout in my shower floor, small 1-2inch square tiles. The pen nib was too wide and shredded within minutes of my trying to use it. I emptied the "ink" into a small container (plastic bottle-top) by poking a cake-tester into the end. Then I painted the grout lines with a very narrow, stiff-bristle artist's paint brush. The ink is bright white and my grout is certainly off white and I only did part of the floor but it seems to blend in well. Certainly looks a lot better than it did before and will delay having to replace the whole thing.NB: GROUT SEALER DISOLVES THE RESTORER so don't do what I did and apply it over the top the next day unless you want to do it all over again!So I did my bathroom last September I believe with the tile grout pen. It works for sure but for a small bathroom I definitely destroyed a few of the tips and wore them out. I was happy for about a month but than I noticed it was fading and going patchy and by January I had to re do all my grout as the paint made it look dirtier and more worn than to begin with.If you are ok with updating every few months or rarely wash your floors than yes it works amazing but I need something more durableThis is a very mixed review from me, because this product is FANTASTIC for small areas but absolute GARBAGE for large areas.My husband and I purchased an older home. The people that lived here before us smoked in the house, and as such, all of our grout was yellow. I went through and scrubbed all the grout, but it still wasn't as white as I would have liked.Enter the Rejuvenate pen. Make sure you shake it really, really well prior to use or it won't go on evenly (trust me on this one). The first few strips of grout rejuvenated like magic, but then...the tip of the pen shredded. You see, my grout is gritty. So I flipped the tip and continued, but once you flip the tip, it doesn't saturate with the solution the same. I used both pens and only managed to do the grout behind my sink (and there's a big section to the side of my sink that is undone still). You have to push pretty hard once the tip of the pen starts getting ragged, and I found that it hurt my wrist a bit.The grout is white and perfect looking, these pens did an excellent job, but because the tips of the pen shredded so quickly, I was forced to throw away both pens with solution still in them. How wasteful!If you have a small grout touch up to do, I highly recommend this product because it WORKS. It really does leave your grout gleaming white. But if you have a larger area (like your backsplash, for example) do not buy this product. My husband and I calculated that I would need 16 pens to do all of the backsplash in my kitchen. If I were to order from amazon, it would cost me $150 to whiten my kitchen backsplash grout. That seems excessive.