Media Blasting Pontoons with calcium deposits at water line


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Puddingstone Lake (Pomona), CA
For the last several years we kept our 18’ Bennington in the water in the marina at the lake where we previously had a vacation home in Southern California. We sold that home and the boat is now a trailer queen. As a result of. Several summers in the water, the pontoons have developed some very rough mineral deposits along the resting water line. I ‘m concerned about sanding given the thin aluminum surface of the pontoon.
I have ordered the Sharkhide kit but was considering having the water line media professionally blasted with round glass beads.
Has anyone else tried this? How were the results? Should I try the Sharkhide cleaner before the blasting?


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You can acid wash them with great success. Get the aluminum brightener from NAPA auto parts, about $18 a gallon. 2 gallons gets all of my toons (inside and out) REALLY clean. Mix it 50/50 with water. IF that doesn't do it, you can always use a bit straight from the bottle, or let it sit longer before hosing off. Easy-peasey. Use a dedicated pump-up type garden sprayer to apply it. You won't believe how clean it will get them.
I tried the NAPA aluminum brightener AND Sharkhide cleaner and the effect was OK but minimal. I saw a YouTube video about a guy who used progressively less aggressive sand paper on an orbital sander. I initially sandEd the dark corrosion line with 180 grit followed by 320, 400, 600 and 800. Although I may never be able raise my right hand above my head again , the toons are glistening. I’ll do another Sharkhide cleaning and then a Sharkhide treatment for preservation.
My current project is to prepare the panels for a vinyl wrap by taking off all of the factory decals. If the tenacity of the Bennington decals are any indication, these boats will last forever. Finished one side and I’ll take it over to Gatorwraps for them to tell me if my surface preparation was sufficient. If so, I’ll do the other side. Going with solid black with schools of swimming skeleton fish... It’s all part of the theme: “Grandfathers - Grandchildren love them, Fish fear them.”
I’ll send photos when finished.
Papa Bear,
Well, I've been a metal guy ever since Christ was a pup. I've sanded oh, maybe 300 miles of aluminum and never, EVER came close to any form of damage. If you look at my toons in the pics below, it took 5.5 days to get them to the appearance you see. And that was 2.5 days of nothing but SANDING!! The process used a *D/A* or, disc/abrasive sander. We started off with 400 then, to 600 and finally 800. At that point, we switched to one of the rouges. There's brown, green, red, white and black. I forgot which we used first but, like the sanding, we graduated to a finer rouge. The last part of the process was using the D/A unit only, to apply a soupy version of Mothers. Only it wasn't mothers. It was a couple different rouges and some liquid. Then, it was time to remove that polish. The end result is what you see. Lots of work for sure. But, we don't move that boat an inch without getting compliments. So, don't worry about sanding.

P.S. Sorry, I forgot I'm on a different computer without my Benny pics. If you look one of my threads about polished toons, you'll see what I'm talking about.