sandblasting a wooden boat

Discussion in 'Wooden Boat Building and Restoration' started by pduhglas, Aug 9, 2008.

  1. pduhglas
    Joined: Jul 2008
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    pduhglas Junior Member

    I am restoring a wooden drift boat and the first step is to sand off the existing paint. Can a guy sandblast wood and not put holes in the boat? If so what type of sand and psi should I use?
     
  2. the1much
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    the1much hippie dreams

  3. alan white
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    alan white Senior Member

    Sand blasting will wreak havoc with wood. Strip and/or sand, or try some other type of grit as seen on the thread mentioned by 1much.

    Alan
     
  4. PAR
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    PAR Yacht Designer/Builder

    Soda ash and dry ice work well on wood, especially dry ice, but it's very easy to tear out the wood, between the growth rings, especially on some species.

    If you must use a blaster (not my first choice) then a 1/2" tip, keep it well back from the work and use a relatively low pressure.
     
  5. lazeyjack

    lazeyjack Guest

    use fine sand, and start at 30 psi,
    a half inch nozzle will use 350 cuft inch at 100psi, so that one very large compresser a 75 cu ft will just abt run a 1/4 nozzle at 100, thats the pressure needed to blast steel
    so volume is the issue here not the psi Toy from walmarts? nah
    sounds like you have access to blaster?
     
  6. powerabout
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    powerabout Senior Member

    try the plastic media's like granulated polycarbonate
     
  7. rwferr
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    rwferr Junior Member

    You might want to look into a chemical stripper product called Peel Away or a heat gun. I just burned off all the paint on my 38 foot Baybuilt from the toe rail up with a heat gun in the last two weeks. It took approximately 40 man hours. I removed 45 years (approximately 15 coats) of paint and the paint chips weighed approximately 14 pounds. I do not think I would personally have used a sandblaster.
     
  8. keith66
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    keith66 Senior Member

    Sandblasting a wooden boat can be successful, i have done it several times with restorations. I used a small gun designed for car repairs with fine carborundum grit on an SE Saunders mahogany launch removing 90 years worth of paint & crud from her interior, the job took a lot less time than scraping & sanding and left a good finish. It is a filthy job and good breathing apparatus is essential. It does not work well on softwood where the growth rings are harder & softer leaving a surface like a worn out old shed!
     
  9. glensail
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    glensail Junior Member

    sand blasting wood hulls

    Your post is perfect for my problem. I've a 5.5M JI racing sloop from 1964 with 47 years of paint on it. The inside looks terrible and impossible to scrap and strip. Prb= Acacia ribs / Philippine mahogany.(soft wood). Can you give me some specifics as to nozzle size, compressor size (CF/M) and what media you found worked best? Maybe how many pounds of media are needed per sq meter or sq foot?
     
  10. keith66
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    keith66 Senior Member

    A company i know of restore Dragons to a very high standard. they recomended crushed walnut shell media for blast cleaning wooden boats. Apparently it is far less damaging than grit.
    Here is a link to a media supplier that is useful info,http://www.guyson.co.uk/consumables/media.html
     
  11. PAR
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    PAR Yacht Designer/Builder

    All media blasting if fought with possible issues, unless the media is exceptionally soft, like soda ash.

    Chemical stripping is a much safer way to go, even on many layers of paint. Considering the cost of media blasting with soda or dry ice, chemical strippers look much more economical too.

    Glensail, this is a 3 year old thread, so you may want to start a new one addressing your specific issues. Your old boat with it's old many layers of paint problem isn't unusual nor uncommon. Chemical stripping is the preferred choice for the sake of the underlying wood.
     
  12. BATAAN
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    BATAAN Senior Member

    PAR is right. Chemical stripping (there are several new ones check the ads in WOODEN BOAT magazine) or in my opinion an option is heat gun. Most professional vessel painter/refinishers use this approach for smaller vessels. Bigger craft need a different approach.
    As an old pro myself on work boats I use a propane plumber's torch on a 5 gal bottle, a carbide scraper and a light touch. Just finished burning all paint off the deck of BERTIE, a fat 40 footer with huge deck space last week. For a heavily built boat (not plywood or glued construction) this is ideal. It hardens and toughens the wood, kills any and all fungus or mold anywhere near the surface and dries it so the primer sticks wonderfully. It is however rather rough if you're not careful and some of the surface inevitably gets slightly burnt and unfair. Good thick build lets you sand all fair but thin plank is not so tolerant.
    The idea of walnut shell blasting medium sounds interesting for the interior of a smooth and highly finished vessel like a Dragon (IOD) and seems to have a good track record according to another post above.
    I used to repair the frames in these for tension breaks and the boats are pretty universally varnished inside. We'd use a heat gun in this instance for stripping in the yard I was employed at the time.
     
  13. PAR
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    PAR Yacht Designer/Builder

    I've blasted with walnut shells and other "soft" media, but it's still fairly easy to blow out wood between winter and summer growth rings, some species are much more prone to this then others. Dry ice blasting is also fairly safe, but costly

    Heat guns and torches work, but can cause damage, can drive oils and other contaminates deep into the wood, etc., not to mention wielding a torch around in the confines of a boat's interior can be problematic. For large projects there are specialized tools that will remove paint safely, typically abating the surface.

    Chemical strippers have come a long way since the days of hold your breath as long as you can around the stuff. Now they're biodegradable and effective. The same goes for stripping rust. I have a product that you just dip a rusty part in. After a few minutes, no rust and any remaining paint is intact! It's reusable and when finally worn out, just flush it down the drain. The same is true of paint strippers. On heavily coated (many layers) pieces, you may need to do it more then once to get down to raw wood, but when you do, you haven't stained, scorched, scratched, marred the wood or raised the grain. Besides, you'll spend a week with a crevasse tool on a shop vac, getting all the media bits out of the nooks and crannies of the bilge if you media blast.
     
  14. BATAAN
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    BATAAN Senior Member

    PAR, what is the rust product?
     

  15. glensail
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    glensail Junior Member

    sand blasting wood

    Wow. Thanks for all the answers..
    In fact the boat (a 5.5M JI) music12.JPG

    music20.JPG

    music24.jpg is VERY similar to a Dragon....lots of nooks and crannies.
    I can't imagine how many hours it'll take. In side and out..before doing the west system coating.
    I plan on trying several medias (soda and walnut shell first)
     
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