Results 1 to 12 of 12

Thread: Ever get lines of varying sheen on a table top after spraying nitro lacquer?

  1. #1
    Join Date
    May 2014
    Location
    Bel Air, Maryland
    Posts
    535

    Ever get lines of varying sheen on a table top after spraying nitro lacquer?

    Just wondering if this ever happens to anyone. I didn't take pictures because the camera was not at the shop but I think I can describe it. It doesn't always happen which is what is weird. I sprayed a table top yesterday and after the lacquer dried, when looking at the finish with an opposing light, it appeared that some of the sprayer passes had more sheen than others. Almost gave a striped effect where ever other pass was clear and the passes in between were slightly cloudy, or, less clear.

    I'm using an Earlex 5500 (which is the most amazing sprayer I've ever used by the way) and nitro lacquer thinned approx 40/60 thinner/lacquer. Because this doesn't always happen, there must be some combination of things I'm doing that are causing this. Maybe I'm spraying too closely? I usually seem to want to spray about 5" off the project. Maybe too much thinner, not enough? Sprayer volume too high/low? I've even wondered, (1) too many drops of fisheye preventative?

    Weird. Hopefully someone here has had this and figured out why. Since I switched to this HVLP sprayer, it has made my spraying results more consistent by a factor of 10. Now I've just got to work a couple little bugs out.

    Thanks!

  2. #2
    Are you lapping each pass of the gun by 50%? A lot of beginners don't overlap their strokes enough and as a result leave dry areas which show up as streaks when dry. (Dirt in the air cap or fluid nozzle can cause this as well) Make sure to get a perfectly even wet pass of finish and use a little retarder if its really hot. Table tops can be challenging because you can walk all around and see it from every angle. When I spray my top coat on a conference table I do three passes of finish. One light tack coat with the main direction of the grain, one cross coat wet pass and then one final wet coat with the grain.

  3. #3
    Join Date
    May 2014
    Location
    Bel Air, Maryland
    Posts
    535
    Quote Originally Posted by Rick Mosher View Post
    Are you lapping each pass of the gun by 50%? A lot of beginners don't overlap their strokes enough and as a result leave dry areas which show up as streaks when dry. (Dirt in the air cap or fluid nozzle can cause this as well) Make sure to get a perfectly even wet pass of finish and use a little retarder if its really hot. Table tops can be challenging because you can walk all around and see it from every angle. When I spray my top coat on a conference table I do three passes of finish. One light tack coat with the main direction of the grain, one cross coat wet pass and then one final wet coat with the grain.

    Light tack coat?
    --

    Sometimes the best solution to morale problems is just to fire all of the unhappy people.

  4. #4
    It is basically a dry coat allowed to tack for a couple seconds. Very good technique on vertical surfaces to prevent runs. The nice thing about lacquer us that it re-wets when you spray another coat. Back when we stilled sprayed lacquers we used to just wet sand the top and spray with just lacquer thinner or Lacquer thinner with just a little finish mixed in. The thinner would re-wet the lacquer already on the table and dried very fast giving a near perfect surface.

  5. #5
    Join Date
    May 2014
    Location
    Bel Air, Maryland
    Posts
    535
    Quote Originally Posted by Rick Mosher View Post
    It is basically a dry coat allowed to tack for a couple seconds. Very good technique on vertical surfaces to prevent runs. The nice thing about lacquer us that it re-wets when you spray another coat. Back when we stilled sprayed lacquers we used to just wet sand the top and spray with just lacquer thinner or Lacquer thinner with just a little finish mixed in. The thinner would re-wet the lacquer already on the table and dried very fast giving a near perfect surface.

    Sorry for not understanding. A dry coat? Do you have a second to explain your process? I very much appreciate it by the way.
    --

    Sometimes the best solution to morale problems is just to fire all of the unhappy people.

  6. #6
    A normal wet coat of finish will look like a sheet of glass, 3-4 wet mils of fluid, which is right on the border of when a run can happen. By doing a tack coat (there are just speckles of finish on the surface basically maybe 1 mil thick) and letting it flash a couple seconds (longer with oil based or catalyzed finishes) you are then able to spray a little heavier coat without runs. On tabletops by doing a cross coat you tend to eliminate any defects in your spray pattern and assure a nice even coat without streaks. You can tell how much finish you are applying by using a wet film thickness gauge. Here is a video showing how to use one. Once you see what the proper amount looks like you won't need to use it as much but if there isn't anyone to demonstrate how much finish to apply it works pretty well.

  7. #7
    Join Date
    May 2014
    Location
    Bel Air, Maryland
    Posts
    535
    Quote Originally Posted by Rick Mosher View Post
    A normal wet coat of finish will look like a sheet of glass, 3-4 wet mils of fluid, which is right on the border of when a run can happen. By doing a tack coat (there are just speckles of finish on the surface basically maybe 1 mil thick) and letting it flash a couple seconds (longer with oil based or catalyzed finishes) you are then able to spray a little heavier coat without runs. On tabletops by doing a cross coat you tend to eliminate any defects in your spray pattern and assure a nice even coat without streaks. You can tell how much finish you are applying by using a wet film thickness gauge. Here is a video showing how to use one. Once you see what the proper amount looks like you won't need to use it as much but if there isn't anyone to demonstrate how much finish to apply it works pretty well.
    You mean like dusting a coat on? Where you hold the sprayer pretty far away and move very quickly, producing an almost sandpaper-like finish?

  8. #8
    Yes. But you are going to go right back over it after it flashes. Try it on a piece of scrap.

  9. #9
    Join Date
    May 2014
    Location
    Bel Air, Maryland
    Posts
    535
    Hey rick -

    I'm doing(already done) a large 10ft dining table. For some reason, I'm getting inconsistent results. Let me explain.

    One of the two leaves I sprayed came out absolutely spectacularly. I used your 3 pass method. One half of the main table came out perfect as well. However, the other side, I can see the streaks I was talking about, however these streaks are from the cross grain second step pass!

    I'm using NC lacquer http://www.lenmar-coatings.com/produ...lulose-lacquer
    and thinning it 50/50 measured.

    I sprayed three coats. The first blushed a bit so I added retarder but I think I added too much because it took a long, long time to dry. Should I be using retarder all the time since I've got a turbine HVLP setup?

    Sometimes I spray and it turns out amazing. Other times, not so much.

    For now, would it do anything if I sprayed straight lacquer thinner on the table top? Would that have any effect?
    Last edited by Mike Dowell; 08-26-2014 at 7:42 PM.

  10. #10
    If it is a conventional nitro lacquer you can wet sand the entire top with 1500 grit sand paper and then spray just lacquer thinner and it will re-wet. If it is a pre-cat or catalyzed lacquer it won't work. Try it on a piece of scrap first. Go very easy on the retarder you only need like 1/2 oz to a cup of finish. I like using MAK (methyl AMYL ketone, NOT MEK) as a retarder. It is not as oily or slow drying as butyl cellosolve or butyl carbitol retarders. When you spray across the grain you still have to get a very even finish, was the table too wide to spray comfortably across the grain? If so just go with the grain on all coats. Also check your spray pattern on a piece of paper. Is it perfectly symmetrical? If there is a slightly clogged hole in your aircap it can cause the fan to deform and cause streaks.

  11. #11
    Join Date
    May 2014
    Location
    Bel Air, Maryland
    Posts
    535
    It was comfortable to spray either direction. Actually, at this point, the one half of the table has too much finish on it and looks absolutely awful. I'm just going to strip it and start fresh.

    Why the 1500g wet sand prior to spraying straight lacquer thinner? That may sound like a dumb question and, it's likely that it is but I've not messed about with any techniques which are "unconventional", ie. spraying straight lacquer thinner.

  12. #12
    You want to remove some of the flattening paste from the surface as well as any dust nibs that may be there.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •