Crushed glass for taking bottom to gelcoat

[Offshore1960]

Crushed glass is a great media for removing paint from a bottom. It leaves a really clean finish and if done in combination with water its virtually dust free. Most of the time this is done using a rotary screw air compressor on a trailer, with the media fed through a large hopper. If you plan on keeping the boat its well worth doing.

[Greg Mason]

I just did a soda blast and it took off everything right down to a rough finish. No blisters, but I took the time to install 2 coats of Interprotect 2000 prior to bottom paint. I also come out every year, so i can keep and eye on the hull.

[Cadence]

If you have vetted the pro you hired, I'd take his advice. I sounds like he may be telling you if blisters exist the blasting may open them up. If it does addressing them now rather than later probably would pay. If it doesn't you will have the warm fuzzies.

[hellosailor]

cb-
Crushed glass is, after all, basically "sand". Quartz sand, some additives, melted, poured out, cast into sheets, crushed back into grains again, but still mostly sand. Pretty conventional way to get down past the gelcoat. Sounds like he is planning to work slowly and carefully, which is important.
If it is an epoxy barrier coat, AFAIK epoxy still pretty much lasts forever if it is a good epoxy properly applied. If the hull is taking in moisture from other sources (i.e. from the bilge) and that's applying osmotic pressure to push the epoxy off, that's something else again. No the epoxy's fault.
Surely he can give you referrals? Or you already found him that way?

[cburger]

Originally Posted by hellosailor

cb-
Crushed glass is, after all, basically "sand". Quartz sand, some additives, melted, poured out, cast into sheets, crushed back into grains again, but still mostly sand. Pretty conventional way to get down past the gelcoat. Sounds like he is planning to work slowly and carefully, which is important.
If it is an epoxy barrier coat, AFAIK epoxy still pretty much lasts forever if it is a good epoxy properly applied. If the hull is taking in moisture from other sources (i.e. from the bilge) and that's applying osmotic pressure to push the epoxy off, that's something else again. No the epoxy's fault.
Surely he can give you referrals? Or you already found him that way?

He has been doing this for many years, its the way he makes his living 7 boats faility alone. Was a great day as I moisture metered sections of the hull and coming up basicly dry, meter went over one of the largest blisters and read dry. Nice to hear that the glass does a nice profile for coating application.

[Pete7]

How about the DIY option

https://www.youtube.com/watch?v=H2Y3BsEB7tY

[cburger]

Originally Posted by Pete7

How about the DIY option

Topsides and cabin top getting painted no time to blast bottom

[takeabow40]

Originally Posted by cburger

Boat has been pulled from water after being in water for almost six years. There are evidence of blisters underneath the barrier coat and I want to remove all coatings down to the gel coat. I started removing some of the paint and barrier coat last weekend with a scraper and there are places where gel seems very thin, evidence of repairs with what appears to be Bondo that needs to be removed and lots of blisters.

I fast came to the conclusion that I don't have the desire to do this work by hand and have contacted a local "Soda Blaster" who looked at the vessel yesterday and is indicating the baking soda won't be aggressive enough to remove the barrier coat and wants to shoot crushed glass to accomplish the work. As part of the conversation he indicates the glass will leave the bottom "Rough" and if there are any voids may open them up. Something else he said that was interesting is he feels barrier coat is only effective for about 10 years.

Wondering if anyone has ever had crushed glass used to strip their bottom and how the job turned out?

Just another blasting media normally used for removing soft coatings or thick ones large particles leaves a hammer finish in the hands of professional good choice or jet grit would be faster I do this for a job .a lot depends on environmental requirements in your area you can wet blast with most media except soda and walnut husks but boat will need freshwater wash afterward to remove the sludge

[Library70]

I had my Lagoon 410 blasted by a professional company using crushed glass. It looked exactly like sand (said "crushed glass" on the bags). It left a texture on the surface that was similar to sanding with 80 grit sandpaper. It exposed some pin head sized dry blisters which I filled with thickened epoxy. After four coats of Interprotect with a 3/8 nap roller and two coats of bottom paint, it looked like a new bottom. When done by an experienced professional, crushed glass is a great product for blasting off bottom paint - but I can't say how well it would work for barrier coat removal. Good luck!

[puffcard]

I'm starting to gets blisters after 22 years. My boat was blasted and 5 coats of Interpotect 2000. Then I with a hard modified epoxy paint like Unipoxy, as a good base for a year. Then follow with ablative. I didn't get blisters till I started going south for the winter. There are different factors that causes the blisters, one for certain is warm water.

[cburger]

[QUOTE=Pete7;2649024]How about the DIY option

https://www.youtube.com/watch?v=H2Y3BsEB7tY

[/QUOTE

My contractor has qoated 3200.00 for the whole job, tents everything, takes all the debris away to be disposed. The boat was hauled to paint hull and topsides a huge job, the bottom came as a complete curve ball and am more than happy to have a pro handle this job.

[nortonscove]

Crushed glass does a great job of removing old coverings but leaves a very rough finish that you will want to fair. The upside is that it offers fantastic adhesion. It will definitely take care of any blisters.

[coastalexplorer]

When sand blasting or pressure washing anything do not wave the wand around all over the place, make slow passes in rows like a spray painter would. and gauge your speed for each pass according to the results of the cleaning. This is much more efficient and uses less cleaning medium.

[cburger]

So the contractor I agreed to use texts me this morning indicating he wants to start the blast work tomorrow, all good I think. Then get text asking me if boat is gel or paint, sets of my alarm bells after all we're supposed to be peeling bottom? I indicated that the hull side are paint and needs to be protected from blast media, his response is tarps are hung from toerail, "Vessel has no toerail" and no tape will be used and blast media will be escaping from top of tarp and I need to make sure all hatches are closed. I ask him why boat can't be tented below water line and material kept off the finished parts of the boat, my neighbors boats and out of the Hudson River.
His response is that my request is unreasonable and that you have to break a few eggs to make an omlette.

[Cadence]

Originally Posted by cburger

So the contractor I agreed to use texts me this morning indicating he wants to start the blast work tomorrow, all good I think. Then get text asking me if boat is gel or paint, sets of my alarm bells after all we're supposed to be peeling bottom? I indicated that the hull side are paint and needs to be protected from blast media, his response is tarps are hung from toerail, "Vessel has no toerail" and no tape will be used and blast media will be escaping from top of tarp and I need to make sure all hatches are closed. I ask him why boat can't be tented below water line and material kept off the finished parts of the boat, my neighbors boats and out of the Hudson River.
His response is that my request is unreasonable and that you have to break a few eggs to make an omlette.

Maybe you and he need to get together. He may be speaking of a minimal amount of glass getting out and only wanted to warn you of it such that you didn't have it getting below. Toe rail, I think your spitting hairs. Tenting from the waterline seems impossible.
I believe, maybe you should leave it to the "professional" and not second guess him or do it yourself.