Takes so little to cover and dries to rock hard rusty-black (can dry pitch black but can dry with hint of rusty brown , but NOT any rust left).The BEST part for me is that I can buy one of those premium trigger spray bottles from garden section and that trigger top screws right on here. When complete with task, remove trigger head, spray product remaining in tube back into bottle; you are safe to do this because the product in your bottle has not contacted any rust. When done, a little soap and water and triggering same through nozzle, all done!DO NOT RETURN EVEN THE SMALLEST DROP OF ANY UNUSED PRODUCT OF WHICH YOU MAY HAVE POURED INTO A DISH OR CUP FIR USE; DIPPING APPLICATOR OR BRUSH INTO THIS POURED PORTION ADDS RUST WHICH WILL REACT WITH AND RUIN THE REST IF POURED BACK INTO ORIGINAL BOTTLE. This is a true polymeric rust converter and worth every penny.Great product. Works like it is supposed to. Great for rust repair.Didn't know this kind of product existed, but it is quite impressive. Used a sponge paint applicator to paint surface rust on vehicle frame. takes a day or so for the chemical reaction to complete, but solid black metal where rust used to be. Didnt take much so this one bottle will do a lot. I did try on my grill with not as impressive results and assume that was due to the type of metal (but that wasn't my intended purpose)I opened my bottle 5 minutes ago. I shook bottle before opening. Seal was intact. Removed seal. 80% on the bottle is a solid mass. 1/2 a cup of chemical came out. I tried pushing a large screw driver down the bottle to see if it was a surface issue. The solid mass is all the way to the bottom.I have purchased this before. This is not how the product comes. There is a problem.The product generally comes out like shampoo. You paint it on and it does a great job. My first bottle was 5 stars! This bottle would be less than 1 Star.This works very effectively. I have been using this to refresh an old pickup truck. The truck is in reasonable shape, but has a lot of surface rust on in. A good wire brushing, and application of this product, and it's ready for a good coat of paint.It did an excellent job doing the very thing I wanted. This project was a success! ThxWorked great. I used this as an alternative to the POR-15 metal prep when prepping the under carriage of my jeeo for paint. Product turned the rust black and I was able to lay a good layer or paint over it.I used two bottles of this stuff to completely restore a trailer that had a ton of surface rust. I hit the areas with a wire brush, wiped it clean, and applied 3x. It produced a really hard black surface from which I sprayed on the new finish. That was over 1yr ago and no issues.