how to get a dead flat table top

Discussion in 'Boatbuilding' started by Charlyipad, Jun 25, 2015.

  1. Charlyipad
    Joined: May 2014
    Posts: 218
    Likes: 7, Points: 18, Legacy Rep: 57
    Location: St Simons is ga

    Charlyipad Senior Member

    Guys I am building a cockpit table on the cheap. I used 5mm no name ply from the big box, vac bagged it onto a one inch sheet of pink panther foam, and hand layed up 18 0z biax on the bottom, and then 12 oz uni over the ply on top . All this was with leftovers so it didn't cost anything. Oh and I edged it with some planed down spruce.

    OK but I may have messed up. I ran out of resin so i started coating the thing on top with varnish, thinking that it would hide the weave from the uni with several coats built up. It has done that, and the wood grain and all looks great, but no matter how careful I am it just docent come out FLAT and p u r t y.

    How is the best way to get a dead flat top with varnish? The table is about 36" wide by 60 inches long. Ive been using foam brushes. THAnks.
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Spray the coats, with an appropriately cut varnish or polyurethane, maybe with a flow control modifier if necessary. A turbine style, HVLP setup for about $150 bucks will do a good job or you can rent something better. The Wagner hand shakers just spit and sputter for the most part. If you're really on the cheap, use the Peval sprayer, available at big box stores. They'll put down a pretty nice finish, once you get a handle on how to use them. Lastly, you could just use an aerosol spray version of the varnish you're interested in.

    [​IMG]
     
  3. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,003
    Likes: 356, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Being less than a perfectionist, I'd go down to a sheen level where you no longer notice irregularities !
     
  4. Charlyipad
    Joined: May 2014
    Posts: 218
    Likes: 7, Points: 18, Legacy Rep: 57
    Location: St Simons is ga

    Charlyipad Senior Member

    there are plenty of imperfections all over the boat to notice.:D

    Most of them don't bug me, but when sitting at this table in a certain light, you can really see the "waves".

    Somewhere I read about adding shellac to epoxy for a flow coat. Would adding shellac to varnish work?

    Its been in the mid nineties farenheit here, probably about 1000 degrees centigrade. Maybe it is too hot to be doing this.
     
  5. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,003
    Likes: 356, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    The old saying that paint hides the biblical "multitude of sins" is doubly applicable when you reduce the gloss level, matt or low sheen only shows flaws at very low viewing angles.
     
  6. AndySGray
    Joined: Jun 2014
    Posts: 296
    Likes: 13, Points: 18, Legacy Rep: 91
    Location: Cayman

    AndySGray Senior Member

    While the normal technique with varnish is to over thin the initial coats allowing it to soak in better, as the wood is sealed now, use a painting type technique and apply a thinner final coat to allow the finish to flow more and 'self level' with a much longer drying time.

    Paul has nailed it with respect to a perfect finish and you can't do better than spraying...


    But it is possible to get a perfectly good finish with brushes.

    Buy a good quality brush, for that size job around 3" to 4", natural bristle is my personal choice.

    If it is new bristle, spend 5 minutes 'dry painting' a sheet of 220 grit sand paper - this will smooth and polish the end section of each of the bristles and allow the paint to flow much better.

    Now use a brush or comb to 'comb' the new paintbrush, a new brush will always moult a few bristles and they mess up the job badly - have an old cardboard box around so you can partly dry the brush and help it to lift the errant bristle which can then be painted onto the box or scrap wood if it does happen.

    Painting or varnishing by brush has three main stages.

    The paint is applied to a dry area of the panel and then spread out by brushing in and out from that new centre in a starburst pattern - direction is not important at this stage you're spreading out the paint/varnish.

    The second stage is to even out the layer - medium pressure with the brush working in 2 directions e.g. left and right parallel strokes until the new area is covered, then start again in a different direction e.g. up & down or a diagonal. You need to keep going until the area is even - the drag on the brush will feel the same all across the area and you can work wet areas into drier ones. You also need to join this area into the wet edges of the previous areas.

    The final stage is to overbrush the area in only one direction e.g top downwards, working in the direction of the grain, slowly and with very light pressure the brushmarks will disappear very quickly, long continuous strokes. I overbrush once I have done an area/patch and when the whole thing is done I overbrush the entire piece. The finish needs to be thin enough that once the coat is on it is still wet enough where you started to allow you to overbrush.

    If varnishing sanded wood, don't rush it, the varnish will raise the grain and so you need to flat it back between coats - so it needs to be properly dry.

    Now thoroughly clean the brush! :!:;)
     
    1 person likes this.
  7. SukiSolo
    Joined: Dec 2012
    Posts: 1,270
    Likes: 25, Points: 0, Legacy Rep: 271
    Location: Hampshire UK

    SukiSolo Senior Member

    One other thing is that over about the first year, the finish will sink into the grain or weave. So be prepared to recoat after this time, usually it stays pretty flat after this later finish coat.
     
  8. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It takes a fair bit of experience to learn how to "flow" varnishes into flawless coats.

    A simple, if tedious method is to simply bulk up the coating, then knock it down, until it's deadnuts smooth. Start blocking down with wet 600 grit, to remove the worst of it, moving through 1,500 or 2,000 wet. At this point you can just start buffing and I'd start with a 3,000 pad from 3M, moving to 5,000, then a quality polish. If the gloss is too much, instead of polish, use a cutting compound at 3,000 grit and leave it at that. You'll have a dull sheen, sort of a satin look, that will hide many flaws, but still look good.
     
  9. SamSam
    Joined: Feb 2005
    Posts: 3,818
    Likes: 156, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    what i would do is build the finish above the glass. then sand with 100 grit using a large sander, like 1 or 2 pieces of paper stuck on a flat piece of ply. once it gets flat, use some 220 for a little bit. for the final few coats, use a pad of t shirt cloth folded up so you are not dragging edges across the wet varnish. that way very little is applied so there is no chance of brush marks or puddling and the coat is so thin and it drys to the touch real quickly so no dust or bugs get trapped in it. in between coats hit lightly with the finest steel wool you can find. they have 4 sheens to polyurethane/varnish-gloss, semi gloss, satin and flat. the less gloss, the fewer imperfections show up.
     
  10. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 9, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    I know a lot of you guys have forgotten more about varnish than I will ever know, but I always wind Wikipedia a great starting and jumping off place for just about any subject, and varnish seems to be no exception...

    https://en.wikipedia.org/wiki/Varnish

    p.s. Interesting trivia. The true vegans, not just vegetarians but vegans in the original British sense, won't use shellac because it is an animal product, being made from insect wings.
     
  11. SamSam
    Joined: Feb 2005
    Posts: 3,818
    Likes: 156, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    So, how did the top go?
     
  12. Charlyipad
    Joined: May 2014
    Posts: 218
    Likes: 7, Points: 18, Legacy Rep: 57
    Location: St Simons is ga

    Charlyipad Senior Member

    Sam, I haven't had time lately to devote to it. I think I will do it like you describe though, but I have a few spots to gouge and re wet where the cloth didn't quite saturate. Heck, if I am going to this much trouble I might as well do that first.

    Also there are some spots on the spruce edging. I didn't coat them with epoxy, thinking that the overcoats of varnish would hide the few wet spots where the epoxy got on the bare wood. so far that is not the case after about five coats. I may wood that too and start over. or not:D

    anyways I dropped my camera overboard. when I can afford a new one I will put up some pics.
     
  13. Deering
    Joined: Feb 2005
    Posts: 477
    Likes: 23, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    You might consider using a 'bar-top' flowable epoxy finish. One product is Mirror Coat by System Three. Sand your top with 220 grit. then follow the instructions. Generally you mix the two components really, really, really well. Then pour it on the top, spread it a bit with a rubber squeegee and let it flow out and self-level. Generally takes a few coats to get a thick, really hard build. You can also encase stuff in it - I entombed a nautical chart of the area.

    Three key things to remember: 1. Make sure the tabletop is really level. You'll get spillover, but you can clean that up with a sander later. 2. Make sure you mix the two components really well or you'll get a sticky mess. 3. Leave it to set overnight in a dust-free, and bug-free environment.
     
  14. Charlyipad
    Joined: May 2014
    Posts: 218
    Likes: 7, Points: 18, Legacy Rep: 57
    Location: St Simons is ga

    Charlyipad Senior Member

    hmm. I was thinking that stuff wouldn't bond to varnish. With some good tooth you think it would?

    This was supposed to be a cheap project:D
     

  15. Deering
    Joined: Feb 2005
    Posts: 477
    Likes: 23, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    It would bond no problem. Sand with 220 and wipe off with iso-alcohol and you're good to go. Cheap? Not so much...
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.