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Sandblasting wood and brick

Posted by wbherndon (My Page) on
Fri, Mar 3, 06 at 3:19

Hi I am in the beginning stages of renovating an old home. One task ahead is stripping a lot of wood (decks, porch, original siding) and really dont want to do it by hand. I've been researching air compressors, and sandblasting kits, but I'm not finding much info on sandblasting wood to strip paint. Is that not a logical/economical function for a sandblaster? Any other methods that are effecient? And what media do I use?

Thanks in advance for any help!

Brad


Follow-Up Postings:

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RE: Sandblasting wood and brick

Sandblasting wood or brick is a rather dangerous task---for the wood/brick. The equipment for a large job is rather expensive---a commercial compressor---like the ones used in street work---is needed due to the amount of air volume needed. And the tank for the sand is about the same size as a 60 gallon standup air compressor.

The sandblasing itself easily destroys wood---removing the softer areas almost instantly and will abrade brick as well.

Paint stripping or sanding takes much longer, but is much easier on the wood and stripping/wire brushing the brick is safer for the brick.


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RE: Sandblasting wood and brick

Beware of lead if the paint is pre-1970's, especially if sanding, scraping or other methods that create dust out of the old finish. Can't recall the year when they completely banned it from paint.


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RE: Sandblasting wood and brick

The only technique as bad or worse than sandblasting for paint removal is a propane torch, so look into that one while you're at it.
Cons: Destroys smooth mill finish of wood.
Texturizes smooth wood. Makes wood more prone to absorb water. Increased porosity will require more paint. Will etch glass. Allows all of the paint to become airborne - huge problem if it contains lead. Dropcloths will have to be used everywhere to contain blasting media. Requires large industrial (V-8 engine-powered) compressor. Requires full-body protection - very hot uncomfortable hood, too. On brick: destroys hard outer surface of old, low-fired brick, making it too soft to ever be out in weather again. Will affect softer briks more than hard ones, so surface may lose its flat appearance.
That said, it is a necessary evil in very limited instances, such as removing paint from old cast-iron facades. Other media than "sand" is available with greatly-lessened abrasive qualities. It is possblie to use a softer abrasive and at least diminish the damage to remediable levels.
If you have a home that is historic or could later become historic, keep the sandblaster away!
Casey


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RE: Sandblasting wood and brick

I believe a lot of the people who replied to you have a fetish for tedious manual labor.

You can sandblast wood and brick just fine IF YOU'RE CAREFUL, and repair/refinish it correctly. For example if you're sandblasting brick, you'll probably need to replace/repair some bricks and mortar when you're done. You'll also need to re-protect the blasted surfaces with a clear coat. (ie. http://www.polyvine-shop.com/coatings_cl.php )

You can purchase wet sandblasting equipment that hooks up to your pressure washer, or dry depending upon what you're doing.

http://www.nextag.com/sandblaster-kits/search-html
http://www.chpower.com/webapp/wcs/stores/servlet/chCat2_10051_10001_10718_-1_10676__


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RE: Sandblasting wood and brick

But can you point to one of the positions that I stated and refute it?
Every part of what I said was 100% true.
Beyond that, when working on a vintage house which is part of our cultural heritage, the original materials, craftsmanship and design should be taken into account. Abrasive/destructive methods that cause irreplaceable loss of original fabric are to be avoided. Once the material is gone, and washing away down the storm drains with the next rain, it can't be put back no matter how much bondo, epoxy, DAP or Behr you care to throw at it.
Sealer on the old brick? Oh, really? What's the point of turning a low-maintenance brick exterior into a high-maintenance one with a sealer that will discolor and need to be refreshed every few years? No exterior clear sealer is a permanent fix, they all degrade over time.
I also stated that if you must blast, look into a medium that is non-destructive/ low-abrasive. We have blasted a 1790's stone house using black slag media. It is softer than the stone, but harder than the dirt and paint, and was approved by the National Trust, which owns the exterior preservation easement on that particular structure.
On the menu is cheap, fast, and good, but you can only pick two.
Casey


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RE: Sandblasting wood and brick

" You'll also need to re-protect the blasted surfaces with a clear coat."

This is really going to protect the brick with its hard fire layer stripped off.

Bricks are not uniformly hard all the way through.

There is a hard surface skin that gives most of the weather protection, but the core of bricks is not nearly as hard.

Stripping away the hard outer layer makes the brick now vulnerable to freeze/thaw damage and allows it to absorb excessive water.


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RE: Sandblasting wood and brick

Can wood or brick be sand/water blasted? Sure.

Is it a good idea? Usually no.

Can wood/brick be sand/water blasted correctly. Sometimes.

Brick can be MEDIA blasted rather easily with little danger to the hard outer layer that makes brick weather rersistant. Nut shell particles, grain hulls, and plastic can be used---by TRAINED personnel.

For instance, take the easily rented/bought electric water power sprayers available. 1,300 psi, often the lower pressure setting on a two setting unit is still powerful enouigh to cut/gough some wood decking/siding products.

Point is that if a DIYer does not do the required research and use the correct equipment, really expensive problems will be the end result.


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