Liquid Sandpaper is meant to be used as a de-glossing agent if you want to paint over a surface that has had a high-gloss coating. I can’t tell that it works any better than a piece of sandpaper, or if it does anything at all.
I had the chance to try this product by Klean-Strip on some shelves that had high-gloss enamel paint on them. It is meant to be used on paint, varnish, enamel, stains, and factory coated shiny surfaces such as cabinet doors, etc. The idea is that you wash the surface with this product and you can skip roughing it up with sandpaper to help the new paint to adhere.
It is labeled to be pretty nasty stuff. You are supposed to wear chemical splash goggles, and it is suggested that people with sensitive skin wear rubber gloves. I didn’t wear gloves, and didn’t notice any problems with getting it on my hands. It didn’t smell nasty either. You aren’t supposed to get any of this product on solvent-sensitive surfaces such as vinyl, plastic, rubber, etc.
You saturate a clean, rough cloth with the product and rub it thoroughly over the surface you want to treat. It needs to dry for 10 minutes, but preferably not more than an hour for best adhesion of the new paint.
I did all that, and couldn’t tell any difference in the shelves at all. So... I have to go on trust that this product performed the way it is supposed to. I painted them with primer and then paint... seems just like any other paint project.
Frankly, I think it would have been just as easy to go over the shelves quickly with sandpaper, and it would definitely have been cheaper. Perhaps there are situations where Liquid Sandpaper is really the best choice, but I did not find it.
This was purchased at Home Depot for $4.99 for a quart.