media blasting plywood interior (using walnut shells?)

Discussion in 'Wooden Boat Building and Restoration' started by purvisgs, Dec 12, 2008.

  1. purvisgs
    Joined: Oct 2008
    Posts: 3
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    Location: wa state

    purvisgs New Member

    I am considering a "cheap-o type" sandblaster hooked to air compressor for removing old paint on the INTERIOR of a glass (sheathed outside) over plywood 37' boat. I would like to strip down to bare ply /stringers/ fiberglass (glassed bilge area, some glassed seams inside, but the vast majority of the area will be plywood).

    I have used this type of sandblaster for other applications, but never on fiberglass or wood, and only using sand, not other medias.

    I would like to hear your thoughts about the suitability of a cheap-o sand blaster for these medias (I am not set on walnut shells, but I know that they are available locally. Have not looked into other medias but SHOULD I?

    Would this even be possible in a semi- to fully confined space? (obviously: good respirator, etc)

    It just seems like this is my best option for removing ALL the paint because there are many areas that I will not be able to touch with any type of grinder or sander.

    How much media would you guess that I would use stripping the entire interior of a boat this size?

    thank you!
     
  2. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    We sandblasted tanks on the mine - LOTS

    i like the idea because the amount that you take off can be controlled by the distance of the nozzle from the work piece

    i would experiment with different media

    may be difficult but if you can get it working IT SURE is good
     
  3. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    Manie has it! The key is the Media. The Stuff he uses on his tanks is too aggressive and impossible to clean up afterwards.

    I had an experience with some pretty cheap media that taught me that lesson.
    I lived in Louisiana. All the Creeks down there have a white sand. Lots of it.
    I had a truck with some rust, I thought I'd do something with and paint.

    I got one of those Cheap sand blasting guns, my little 90# continous (Breathless) air compressor and some five gallon buckets of that bueatiful White Sand.

    Real sand blasters use lots of Air, an aggressive media, and time. T
    hey also use a Hood with a breathing apparatus to protect the shooter.
    I got some cheap flannel from a Yard goods place, some plastic goggles and cut eyeholes for the goggles, glued the Goggles to the Flannel and that was my Hood. I had protection from those minute particals that cause you breating difficulties. You must do that!

    Anyway, the beach sand did a wonderful job of cleaning that paint and all the loose rust off the problem parts. The Prep stuck good and the truck still looked pretty good 10 years later.
    They told me the White Sand wouldnt do the job, and it didnt. It wont take Poop off a Baby's butt, but it polished all the dirt off the paint that was stuck to the Truck.

    Back inside your boat again....The deal with paint is when it's stuck to the plywood or hardwood pretty good, you dont really want to sand it off to the bare wood.
    It's got a good grip on the wood as it is. So just clean it up good, primer and paint over it.

    In Washington you might find it tough to locate Sand that dont have lots of Silt in it, but Washington has lots of Granite in its sand. It should be good sand for what you want to do.
    If you can find a Sand bank get a few buckets of sand, strain it through a 1/4" screen first, then through a smaller mesh like a house window screen and make a test blast on the boat. Dont worry about washing the silt out of it. I did that and it wasnt worth the effort. Didnt make things any better.
    Beach sand with Salt might be a bad deal though.

    If you dont have real clean dry sand, nothing's gonna work. Store your sand off the ground, not on Cement either, up on a pallat board is best. Inside where its dry and warm.

    PS: In South Seattle, on the North end of Lettitia street, there was a Sand bank we played in back in the 50's.
     

  4. purvisgs
    Joined: Oct 2008
    Posts: 3
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    Location: wa state

    purvisgs New Member

    I have not looked into sand (grades/ medias) yet. I know that I wouldn't want to use the coarse beach (saltwater) sand around me. (does salt = bad idea for going through the "gun"?) Most rivers around area (little it of a drive) are probably silty as you say.

    I found that some people are using "Zilla" brand lizard litter cage material from petsmart = ground english walnut shells.

    I have no idea how much I would go through and how this compares price wise to buying from an auto body or marine type store if I can find anything locally.

    thanks
     
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