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Thread: Hard impregnating finish?

  1. #1

    Hard impregnating finish?

    Hello SawMillers –

    I’m seeking to improve my meager woodworking skills and looking for some pointers. To be honest, my project is to build cabinets for a Sprinter camper van that I’m outfitting – but I won’t be happy with the usual crap job. I’m seeking to honor the approach of my late father, who did meticulous work. I foresee learning ply bending in my future.

    Right now I’ve got a finishing question. Probably my first mistake, I have large sheets of Baltic birch ply for flooring that I’ve cut tight tongue & groove joints but have not proceeded further. To combat the softness of the birch, I’d like to impregnate the top ply with some clear hardening polymer / resin, but don’t know the best product to use.

    I tried System Three Clear Coat, but it was too viscous to penetrate any notable depth. I might buck the instructions and thin with acetone and try again.
    www.systemthree.com/products/clear-coat-low-viscosity-epoxy-sealer

    For less fussy projects I’ve used wipe-on Poly and it’s a contender because it is pretty thin. I’m curious about two part and catalytic finishes and if these might be hard.

    Likely making this more difficult, I am going to stain the wood grey, and the stain I like is General Finishes Grey oil-based Gel Stain. The thick oil stain gives a differential color with the wood grain, while water based-stains make for a more homogenous and blah flat color. But the oil stain will block wood pores more, making my resin penetration goal harder to achieve.
    generalfinishes.com/wood-finishes-retail/oil-based-wood-stains-sealers/oil-based-gel-stains

    Here’s what I *think* is the order of operations. Please steer me in the right direction!

    1. Cut tongue & groove joints
    2. Sand joints perfectly flush to a grit #? that is good for staining and penetrating
    3. Stain the tops of the pieces and let dry for plenty of time
    4. Glue the tongue & groove joints. So far am intending to use System Three T-88 epoxy. Will test to make sure any squeeze-out doesn’t remove the stain. www.systemthree.com/products/t-88-structural-epoxy-adhesive
    5. Add unknown clear impregnating coat on top. No sanding or I’ll remove stain, right?
    6. Keep adding coats of who-knows-what clear coat. At some point there will be enough buildup that I can sand without breaking thru to the stained wood.
    7. Maybe the topcoat should be traditional wood floor oil-based polyurethane, like Bona?


    What products could I test for the impregnation???

    Be gentle… I’m kinda a beginner. What I learn on this flooring project I’ll apply to fussier cabinet projects in the near future… I’ve got *ideas*!

  2. #2
    Join Date
    Mar 2003
    Location
    San Francisco, CA
    Posts
    10,304
    Finishes appliied outside a vacuum chamber don’t so much impregnate as they make a coat on top on the wood. And wood finishes, at the heart of it, are basically plastic, so that’s the hardness you get.

  3. #3
    Join Date
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    Location
    WNY
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    I would use a commercial vinyl flooring product in a camper van. Much less work; much better durability than anything you can make yourself; probably for less money, too.

    John

  4. #4
    You may be going about it wrong. Cabinets in a camper even though they may not get rained on would be considered an exterior product. It would be exposed to much more heat and humidity than cabinets in a kitchen so the wood is going to expand and contract more. If you use a really hard finish it won't be able to deal with the wood movement and likely start cracking and lifting. You would be better off using a marine grade spar varnish even though it is softer. It needs to be elastic enough to deal with the wood movement and therefore it's a softer finish.

  5. #5
    Quote Originally Posted by Edward Dyas View Post
    Cabinets in a camper... ..would be exposed to much more heat and humidity than cabinets in a kitchen so the wood is going to expand and contract more... ...You would be better off using a marine grade spar varnish even though it is softer...

    Edward - sounds like sage advice! Do you have a favorite marine spar varnish? I'm headed to a couple finishes supply stores in the next day or two and will seek something that can take the big environment swings. I did pick up a some finishing books from the library but will go back and try to learn from boat builders' experience (a.k.a. teak & holly finish)!
    Last edited by Ralph E Burns; 09-15-2019 at 8:05 PM.

  6. #6
    Quote Originally Posted by Ralph E Burns View Post
    Edward - sounds like sage advice! Do you have a favorite marine spar varnish? I'm headed to a couple finishes supply stores in the next day or two and will seek something that can take the big environment swings. I did pick up a some finishing books from the library but will go back and try to learn from boat builders' experience!
    The best spar varnish on the market is Epifanes. It's formulated to use to use on the deck of a boat. It's available at places that sell boat supplies and a little pricy. A cheaper spar and easier to locate that I could recommend is Cabot spar varnish. The only one I would really stay away from is Helmsman spar urethane. It won't last very long at all.

  7. #7
    Quote Originally Posted by Edward Dyas View Post
    The best spar varnish on the market is Epifanes...
    I phoned Epifanes and spoke to tech support (Jason S.). He stressed that because my wood is plywood, it is already dimensionally stable due to the glued layers. As such, he recommended Epifanes 2-part polyurethane for durability over their clear varnish.

    From our conversation, I heard:
    (1) Use 2-part PU: https://www.epifanes.com/page/clear-gloss-or-satin First coats gloss, top coats satin.
    (2) Thin first coat 25%: https://www.epifanes.com/product/00/...hinner-1000-ml
    (3) Thin second coat 15%.
    - Don’t thin after the 2nd coat?
    - Apply coats every 24 hours for chemical bonding without sanding.
    - After several (4-6) coats, cure for > 48 hours and sand flat before applying satin topcoat. Not sure what grit, but the word was don't go crazy.
    (4) Roller-apply: http://www.epifanes.com/product/00/R...over-Moltopren

    I could use the System 3 epoxy sealer already bought on the underside.

    I'm interested in learning to spray when it comes to applying the cabinet finishes; perhaps a large airbrush could be reasonably suited to my small projects.

  8. #8
    To combat the softness of the birch, I’d like to impregnate the top ply...”

    Who wants a pregnant piece of wood, lol?

  9. #9
    That polyurethane is recommended for an interior finish. When a product says for interior use it generally means a place that is climate controlled. I think the application you are planning calls for an exterior finish because of the temperature and humidity swings.

    If you plan to use a roller you might better try it on scrap first. Some of those foam rollers put a lot of air bubbles in the finish. I've quit trying to roll varnish for that reason. I either brush it or spray it.

  10. #10
    Hard wood impregnates!

  11. #11
    Quote Originally Posted by Edward Dyas View Post
    That polyurethane is recommended for an interior finish. When a product says for interior use it generally means a place that is climate controlled. I think the application you are planning calls for an exterior finish because of the temperature and humidity swings.

    If you plan to use a roller you might better try it on scrap first. Some of those foam rollers put a lot of air bubbles in the finish. I've quit trying to roll varnish for that reason. I either brush it or spray it.
    Thanks again @Edward !

    I did tell Jason at Epifanes that the temperature swing would be -10F to +150F. Sounds like his recommendation is because it's plywood flooring. He recommends this finish for longevity on boat cabin soles - the teak & holly flooring. So I will try some... since I have to mail-order the question is do I just buy enough to sample or enough for the whole job (it's spendy!).

    I will buy the Epifanes-brand foam rollers... but am interested in spraying. What I could do without investing huge bucks? I have a 2-gallon air compressor.... did spray PU paints before using an artist's airbrush... wonder if I could do that since the jobs are small (first job = 56 sq feet).

    From the Epifanes guy:
    "Brushing/rolling: You can thin a little if needed but less than 10%
    Standard HVLP gun is best 1.4- 1.8 tip at 15-20% Spray thinner
    Sand with 320 for best finish"

    He did stress that thinning embrittles the finish.

  12. #12
    The airbrush would be too small. You could use a cheap harbor freight sprayer to spray the finish. They do well for wood finishes. I use the model #69704 which I get for about twenty bucks with one of their 20% off coupons. With that size compressor you couldn't spray very much at one time before the pressure would drop too low. If you could spray the doors separately it would help a lot. It's just when you spray an area you can't stop, you have to keep a wet edge on the finish or it will show a line where you stop and start.

  13. #13
    Quote Originally Posted by Ralph E Burns View Post
    Hard wood impregnates!
    Funny- LOL!

  14. #14
    The 2017 Fine Woodworking book "Finishing Wood" reviewed some and Fuji Mini-Mite 3 and Apollo Eco-3 received high marks; both are around $680.

    I might ask Fuji about this $440 one: https://www.amazon.com/Fuji-2203G-Se...dp/B00D4NPPQY/

  15. #15
    Those turbine type sprayers are alright for spraying walls with latex paint but have a bad reputation for spraying woodwork. For that amount of money you should be able to get a descent size compressor and a regular sprayer. The turbine sprayers tend to splatter the paint rather than spraying a fine mist like you need for woodwork and furniture.

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