Davis Instruments790 FSR Fiberglass Stain Remover (16-Ounce)

Easy to use and worked well.

Cleans the lake slime right off the side of boat right in front of your eyes

I've been meaning to write a review on FSR for a long time. I used it once 10 years ago with zero success. I would have given it zero stars. Then I tried it 6 months ago and fell in love. I don't know if the formula changed over the years but what definitely changed was my approach to using it. Instead of slopping it on and hoping for a miracle the first round I decided to apply multiple applications over several days.Here is what I've found. If it's a serious rust stain you're not likely not going to get back to pure gel coat with FSR alone. However, you can get close. Just slopping it on and walking away won't always do it. Try agitating the area with FSR on a q-tip, sponge or rag. Let it sit for 10-15 minutes then come back and re-apply. Wait. Reapply. Repeat. I basically did this to two dozen small rust spots on the topside of my boat over a period of a week. It would only take me 5 minutes to reapply and I just kept doing it until, believe it or not, the spots disappeared.In addition, the bottom had a ton of stains from leaving the boat in the water for a several days without bottom paint. I thought they were there forever until I saw how successful FSR was on the topside. I took a foam paint brush and just slathered it on a 2 foot by 2 foot spot on the bottom of my boat. This faded MUCH faster than the rust spots and in most places only required 2 coats of FSR. For the bottom I would rinse the treated spot with water between applications and this seemed to work great. For the topside I tested both leaving the FSR on and reapplying and removing the FSR first with water and reapplying. I did not find that one way or the other accelerated the process.All said, I am now a big fan of FSR. You just need some patience and persistence to get it work to its full potential.

this was disappointing. It did not remove any of the stains from my fiberglass boat. I would not recommend it nor buy it again.

Have a small area on back of boat thats always been a problem. I've tried toilet bowl cleaners, compound, vinegar, nothing seemed to work. Ordered FSR based on reviews from boat owners forum. Worked awesome. Followed instructions and yellow stains disappeared.

No one product is perfect for everything. FSR works extremely well on removing scum, good on minor rust and most other stains. It is so-so for oil/gas and rubber marks. Our whit hull boat sits in the water for 5 months out of the year. We apply FSR immediately after pulling the boat out, let it sit for 15 minutes and rinse off. Hull is 90% clean, and whatever is left is because we missed it. Typically we reapply again and rinse. Hull looks new. Effective in removing even old scum stains which have penetrated the fiberglass, but this may take more applications. We have a 28 foot Cobalt and will use most of a jar -- which is two applications slightly above water line to centerline of hull, and engine. I use lighter fluid to then remove any gas/oil or rubber marring. This is the best product for this use--hands down. Very strong recommendation. Not perfect for everything but it works as advertised, wipe on, hose off, very effective removal of scum and common stains. Works best when scum is still damp, but will remove dried on and old scum lines. Superior to bleach and all other stain removers I have tried, (and I have used a lot) and as good as the paint on toxic and acidic commercial products which require heavy gloves and gas mask. Great Buy, worth the money.

this stuff is like a jelly that works like a charm. I had no issues removing the who knows how old yellow stain on this 1979 boat. I learned that a little goes a long way and the best way to apply is to use one rag to apply a layer over an area and use another rag or a drill brush to rub it in. I only used the drill brush on rough areas. works extremely well, and if another product is worth more or less I would still buy and recomend this stuff.

Purchased for my father to use on an old fiberglass boat restoration. He was absolutely amazed at how fast and easy this product removed the stains from the hull of his boat.