Sandblasting as prep for new glass

Basketcase · #1 07-30-2014, 09:14 PM

Whoever recommended sandblasting as an alternative to grinding is my hero. I only bought one bag of sand because I wanted to see how well it worked but it worked amazing! I would say that it would cut the prep time for new glass in half even figuring in the the cleanup time. Plus, I think it works better because it gets all the nooks and crannies that a grinder wont get to. I highly recommend it and thank you to whoever gave me the idea!!

ricciprice · #2 07-30-2014, 11:49 PM

Would like to know what media you are using and the what type of gun, pressures, etc., wanting to do the same thing myself, I have the boat ready to grind, but the blasting would make it a lot easier.

Basketcase · #3 07-31-2014, 03:26 PM

I'm low budget here. Its a harbor freight blasting tank with a harbor freight deadman blasting gun. The media is just black sandblast abrasive for autobody work. It cuts through stuff fairly quickly. My compressor is most likely around 90 psi. Its just an old craftsmand 5 horse 30 gal. It doesnt keep up so I have to stop occaisionally and let the compressor catch up.

One question I did have was if there was an expiration date to the fresh surface. Say I blast the whole thing and dont lay glass on it for a month or two is that ok. Ideally id spend a day blasting and cleaning out the whole interior so I can do my stringers etc but I may not get to them right away.

FishStretcher · #4 07-31-2014, 08:52 PM

You should still wash before and after you sandblast- I did acetone/blast/acetone with about the same setup.

Sanel's in Concord has bags, but you can get pallets of black beauty at the PSNH plant in Bow.

I don't know about "freshness". I think rough and degreased and clean is key. I think you can blast and then wait as long as it is clean. I suppose the polyester oxidizes, but I don't know. Some say a styrene monomer wipe instead of acetone is better, but that's a LOT harder to find.

Personally, I really like vinylester. Really reactive, really tough. Really sticky. But the process is like polyester.

ricciprice · #5 08-01-2014, 07:45 PM

Yea that is what I was thinking, as long as it is clean it should stick, probably go vinyl ester here also, just like the thought of an etched surface for bonding. Thanks for the info, black beauty it is...

Basketcase · #6 08-02-2014, 08:56 AM

I have also decided on vinyl ester as I found it at a really great price somewhat local to me. Curious to see how it works compared to poly. I've been working with poly for 15 years and I'm very familiar with it but from what I hear vinyl operates pretty much the same.

FishStretcher · #7 08-03-2014, 01:12 AM

I buy it at Mertons. Super consistent and very reactive to UV and heat. But 3 month shelf life. It is a total PITA to grind out mistakes compared to poly. Way tougher and stickier. And I tune reaction rate with MEKP and up to 10% styrene monomer. A little less stinky than regular poly. Unless I add styrene.

Curious where you get yours.

bigeasy1 · #8 08-04-2014, 12:15 PM

Other than the Epoxy I used to glue the marine fir plywood together with,I did the rest of my transom and motor beds with a mix of polyester and vinylester.Most was done with polyester,but I got some vinylester from Joe at Mertons that we had in some damaged containers for a budget price,so I finished up with it.
At my age,the polyester will hold up and out live me,but if I was a young guy,I'd go with the vinylester,if I was doing a restore.
It's so much easier to wet out fabric with it as compared to epoxy,and the tensile strength and secondary bond,and water resistence is much better than polyester,and the strengths approach epoxy,(and in some cases are even stronger than epoxy).It's also less costly than epoxy.