I need help to learn how to make perfect vernish on our veneered honeycomb panels

Discussion in 'Materials' started by teakcell, Jan 16, 2009.

  1. teakcell
    Joined: Jan 2009
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    teakcell Junior Member

    Hi, I need advices on how to varnish as well as possible on furnitures. We glue our veneer on peeling to make cold moulded furnitures.
    The veneer is glued with epoxy and the glue goes through the veneer because we vaccum. So we use the same epoxy as a wood filler. Then sand paper and lay pu varnish on top sealer and top coat. We have poor results untill now. I need help. Thank you in advance. Laurent
     
    Last edited: Jan 16, 2009
  2. KnottyBuoyz
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    KnottyBuoyz Provocateur & Raconteur

  3. teakcell
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    teakcell Junior Member

    Thank you but I want to keep on using epoxy to glue our veneer for strength reasons.
     
  4. apex1

    apex1 Guest

    Leave it to saturate even!
    If that does´nt happen, feed more resin!
    The prob is not the resin shining through!!! It is the partially dry surface! giving a different pattern.
    Anyway, cover the outside with one (better two) additional layers of very liquid resin. DO NOT USE THINNERS AS MENTIONED SOMEWHERE!!! Sand down to all white surface, thats almost close to veneer. Cover with another layer resin. Sand down to all white, not to veneer. Apply 15 to 25 layers pu. First layer is not sanded! every following just gentle! Last one has to show ALL WHITE again!!! before final spray is applied!!!
    Have a nice, clean shave using that surface!

    And BTW. building a boat in Burma.... chapeau !
    During August 2009 I´ll come to Mandalay again,maybe we meet?


    Regards
    Richard
     
  5. Landlubber
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    Landlubber Senior Member

    teak cell,

    When varnishing the trick is to fill the grain. Apply your varnish first coat thinned out 50%. This will allow penetration through the wood. Allow to dry then top coat with straight varnish, you can thin it a bit (5-10%) if you feel that the product is too thick for application. Allow two to three coats, then sand back till flat, but never sand back to the wood. If the wood shows, stop sanding and apply a few more coats, allowing to dry. Apply about 5 to 7 coats all up.
    Once you have the surface completely filling the grain, you can prepare for the top coat. Sand the final surface with 240 grit paper (320 if you feel the need, but 240 is fine), final sanding with the grain so the scratches from the paper do not show. Wipe down with a clean cotton rag such as sheeting or old T shirt. Wipe down till there is no dust, then get a tack cloth from a crash repairer. A tack cloth is a waxy muslin cloth folded into a small square. Open it out fully and very lightly wipe the surface for the final time. Apply the varnish carefully over this prepared surface and the result will be a mirrored finish.
    When dipping the brush into the varnish, NEVER wipe the side of the brush on the can of varnish as this just drips **** back int the can and polutes the quality. Just dip the hairs in and gently remove, the technique becomes quite natural after a while, and the product remains pure.

    I have been to Burma, and doubt that you can buy a tack cloth anywhere, but try the car repair yards, there may be one there that does quality work, they will surely have them.
    If it proves impossible I will post you some.Just contact me.

    Kind regards, Landlubber
     
  6. teakcell
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    teakcell Junior Member

    thank you well noted. I need to keep on using epoxy for the veneer.
     
  7. teakcell
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    teakcell Junior Member

    Thanks. I will revert when the tests are finish.
     
  8. robherc
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    robherc Designer/Hobbyist

    Maybe varnishing the outside of your veneer BEFORE infusing the part would help? This would eliminate the possibility of epoxy bleed-through harming the varnish....I'm not sure about the possibility of getting epoxy over top of the varnish though, so it might not work out as well as I'd hope.

    Just a thought
     
  9. teakcell
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    teakcell Junior Member

    Nice thought. Thank you. We already tested and it bleeds on the joints.
     
  10. teakcell
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    teakcell Junior Member

    Nice thought. Thank you. We already tested and it still bleeds on the joints.
     
  11. teakcell
    Joined: Jan 2009
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    teakcell Junior Member

    I appreciate you all for kind help and assistance. My results, I shoud rather say my temporary conclusions are:
    - epoxy can be mixed with xylene without a problem as it is a non active charge: it makes the epoxy layer easy to lay. If not, you need to buy special stuff that I cannot find here.
    - Ep + pu bond very well together.
    So after 2 layers of epoxy, lay your pu with the proper gun (need to ask a specialist who will tell you wich gune hole diameter to use). THis might be the most important for us.
    Ly as many PU layers as you need remembering that the more solvant, the more layers, the less the vernish, the higher the price.
    We are studying trying with brush or cotton cloth but we can afford because labor is cheap over here. If I were in EU, I would go for airmix solution ...
    The path to ''varnish mirror'', the real one, is a long path that we are trying to reach.
     
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  12. robherc
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    robherc Designer/Hobbyist

    Hmm, just a thought, I've found that my urethane coats work best (fewest # of bubbles/dry spots per coat) when I apply them with an el-cheapo foam brush (the wider the better), or with a spray-gun (HVLP is ok, but airless is best). If labor is cheap, go with the foam brushes I'd say.

    Also, (and I'm guessing you already know this part) you can MUCH more easily get "varnish mirror" if you do all of your varnishing in a "clean room" with lots of air filtration and NO DUST. I'm working on building a bigger, cleaner room for my projects, because I don't currently have efficient enough filtration; thus, I'm still getting (very) slight surface flaws (granular bumps) in my varnishes.
     
  13. teakcell
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    teakcell Junior Member

    Can you tell me why el-cheapo brand is better. Would you its basic characteristics? Do you have any pictures if the best way you use it? I won't find that brand here and will try with a piece of foam from mattress or sponge and see.
    Could you tell me what is the difference between HVLP gun and others.
    Do you use foam brush for the last coat too ?
    Room is extremely important and we are working on it. We are testing a simple systeme where the room is elevated from the ground (3-4 m) and the air and dust can come out easily. I tried in a 40' container with pressurized air (we just blow a lot of air from the top and it goes out from the holes at the base of the container) with 50% success. We are aiming better so we try a new system. I will keep you informed if interested. Please tell me how you do.
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    There's no way to avoid your bleed through with your method. I just did a veneer deck, using .125" veneers and vacuum bagged them down. Same issue, but I expected it. Top coat the veneers with at least two coats of unthickened epoxy, preferably one formulated to be especially clear. As mentioned, you'll want to "level" each coat with 220, progressing to 320 grit, using a long board on large surfaces. Wet the surface to check for smoothness. If it's not apply more epoxy or use the first few finish coats to complete the leveling process.

    Once satisfied with the "smoothness" of the surface, move on to "bulking up" the finish coating. Basically you want apply successive finish coats, building up thickness and removing minor surface imperfections as you go. Eventually you'll need to apply a top coat. This is the actual finish you'll see and should be applied as neatly and cleanly as possible.

    In fact, the neatness of the result is mostly related to the environment you're working in. The preferred choice for a finsih booth is down draft, where the air comes in from the side and is exhausted through the floor. Of course the air should be well filtered, not a huge volume, just enough to change out the air reasonably quickly without drafts or blowing up dust. It should be able to handle over spray promptly.

    You can dilute epoxy with xylene, but it dramatically weakens the molecular bonds within the epoxy. Adding solvent to epoxy isn't a good idea, unless you have a very comprehensive understanding of the chemistry involved. If you need to change the viscosity of epoxy, you should work at higher temperatures.

    The way I see you project(s) is four fold: bonding the veneer to the substrate, which you seem to have well in hand, secondly leveling the surface so a finish can be applied, third supplying sufficient bulk of base finish and lastly getting a smooth, glass like result from a top coat.

    Conditions will dictate the quality of the top coat, assuming you've applied the material properly. If you don't have truly clean conditions, you'll get dust. Florescent lights create dust, so use a different type of light. It also helps to have the lights at the side of the booth, rather then over head, so you can see imperfections better. Environment control is the only way to get good top coat results.

    Bulking finish coats can be done in moderately clean environments, though you'll have more work to do, "cleaning up" the separate coats of material.

    Getting the veneers smooth with epoxy, takes practice, just like a good automotive body man needs to prefect his craft. With the right tools and practice, leveling epoxy isn't especially hard, but it is tedious and requires a fair amount of skill.
     

  15. teakcell
    Joined: Jan 2009
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    teakcell Junior Member

    With wich tools do you apply epoxy and pu varnish? What temperature do you advise to cahnge the viscosity of ep? Are you sure that xylene does weakens the epoxy as it is supposed to be only a vector of the epoxy: it is supposed to go away when drying. IN my chemistry books, xylene is listed as non active charge.
     
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