Results 1 to 13 of 13

Thread: Finish Issues

  1. #1
    Registered User
    Join Date
    Oct 2015
    Location
    Howell, NJ
    Posts
    246

    Default Finish Issues

    I am doing a spray on sunburst and have encountered a couple of issues.

    I was ready to call the back and sides finished when I noticed a blotch on the back. I suspect the air brush spit a heave drop when spraying Can this be repaired without sanding back and re-doing?

    The top has a specling along the rim. Is this normal or was there an issue with my spraying?

    What is the best way to darken the rim? a denser mixture or more coats?
    Click image for larger version. 

Name:	SunburstIssues4.jpeg 
Views:	114 
Size:	160.4 KB 
ID:	201219Click image for larger version. 

Name:	SunburstIssues - 3.jpeg 
Views:	92 
Size:	92.7 KB 
ID:	201220Click image for larger version. 

Name:	SunburstIssues - 2.jpeg 
Views:	88 
Size:	170.2 KB 
ID:	201221Click image for larger version. 

Name:	SunburstIssues - 1.jpeg 
Views:	111 
Size:	112.1 KB 
ID:	201222
    Bob Schmidt

  2. #2
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    3,168

    Default Re: Finish Issues

    I guess you used stain on bare wood, not colored finish over sealcoat... then th following wouldnt apply.
    The tiny dots on spruce may be caused by contamination. your layer looks quite "dry" almost like your stain dried before it hit the surface, in this case even a piece of dust on surface can cause this. The white lines along binding are glue ghosts.
    If you really want to hide the spot on back (looks more like a finger smudge to me). If the wood surface is smooth and not rippled after application of stain you could sand very lightly just the area of the smudge with very fine paper (I would probably start with 800 grit). I would just lightly touch the area with edge of the paper not even pressing against the wood with backing block, I'd use just springiness of the paper to remove the edges of the smudge and even out the transitions. After that I'd apply a bit more of the same stain with finely set airbrush to even out the color and perhaps add a bit to the whole back as well.
    Adrian

  3. The Following 2 Users Say Thank You to HoGo For This Useful Post:


  4. #3
    Registered User
    Join Date
    Oct 2015
    Location
    Howell, NJ
    Posts
    246

    Default Re: Finish Issues

    Thanks Adrian.
    The back and sides were bare wood, but I did put 2 coats of 1lb cut shellac on the top. I have been perhaps too cautious with spraying too heavy since it seems the alcohol moves the stain around a lot.
    Bob Schmidt

  5. #4
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    3,168

    Default Re: Finish Issues

    Quote Originally Posted by irishmando View Post
    Thanks Adrian.
    The back and sides were bare wood, but I did put 2 coats of 1lb cut shellac on the top. I have been perhaps too cautious with spraying too heavy since it seems the alcohol moves the stain around a lot.
    From what I see, I'd guess opposite. Your stain didn't soak into wood deep enough, the wood looks just misted on surface and that's why the shellac coat dissolves the tiny droplets of dye on surface and moved them. The contamination on top may be caused by spit drops of shellac sealer. (I don't seal tops) Such sealer should be applied extremely evenly and surface drops or dust particles removed with fine gentle sanding.
    I want the stain to penetrate into top layers of wood cells with bare minimum left on surface. Many dye manufacturers suggest gentle wiping of surface with fine sandpaper or rag after the dye dries to remove any leftover from surface which can cause problems with finishing over the stain. I use very fine sanding pad (something like micromesh) and just very lightly rub any dust particles or stain dust from surface, but I never touch lighter areas with a pad that touched darker stain. SInce I do rubbed sunburst and only use airbrush on the darkest parts (not always) so I only have to dust off those areas. After this I seal with shellac, starting with very "dry" coat and apply more after that dries.
    If you want to get lighter shade you need to dilute the stain and not just apply lighter spray coat. There is visual difference in the two.
    Adrian

  6. The Following 2 Users Say Thank You to HoGo For This Useful Post:


  7. #5
    Teacher, repair person
    Join Date
    Oct 2017
    Location
    Southeast Tennessee
    Posts
    3,089

    Default Re: Finish Issues

    One of the hardest lessons to learn in finish work is learning to wait.
    Try Adrian's solution and cross your fingers.
    And see if Sunburst chimes in. He's very good with finishes.

    My 2 cents:
    Solvents move stain. Let stains set twice as long as you think you need to.
    The first coat of finish over stain must be light. Let set twice as long as you think you need to. [Or more].
    The second coat, ditto. Let set twice as long . . .
    Repeat as necessary, and wait some more until the color is well sealed.

    Only when the color is well sealed can you start building faster. Easy to say, hard to do. I don't like to wait, and plead guilty as charged.

    If nothing else works, you probably don't have too much stuff on there to take most of it off and start over. Much as I dislike do-overs, I dislike visible goofs in my work even more. Good luck. Working with color is a real "trial by fire."

  8. The Following 2 Users Say Thank You to rcc56 For This Useful Post:


  9. #6
    Registered User sunburst's Avatar
    Join Date
    Nov 2003
    Location
    Kentucky
    Posts
    15,397

    Default Re: Finish Issues

    I haven't read everything here yet, I only have a minute or two right now so some or all of this may have already been said, but I would probably use some brown dye in the airbrush and a little sepia ink on a quill to attempt to touch up the back smudge. I might start by scraping away some of the darker parts because it is relatively easy to darken things and nearly impossible to lighten things.
    Then when that didn't work, probably sand back and try again.
    The speckling of the top is ray fleck in the spruce; just part of the wood. It can be "painted over" with sprayed dyes if you don't want the look.

  10. The Following 2 Users Say Thank You to sunburst For This Useful Post:


  11. #7
    Registered User
    Join Date
    Oct 2015
    Location
    Howell, NJ
    Posts
    246

    Default Re: Finish Issues

    Boy trial by fire is an understatement although I am guessing it is the only way to get better at it.

    Thanks for the help, I will attempt to repair it before I sand back and start over.

    John, I actually like the look, I was just afraid I was doing something wrong.
    Bob Schmidt

  12. #8
    Registered User sunburst's Avatar
    Join Date
    Nov 2003
    Location
    Kentucky
    Posts
    15,397

    Default Re: Finish Issues

    Quote Originally Posted by irishmando View Post
    John, I actually like the look, I was just afraid I was doing something wrong.
    I kind of like it too. It shows that the spruce is well quartered, and it's referred to as "silk". Guitar people have prized it for years, but mandolin people, not so much. Why? Because the wood used for Loar tops was usually not too well quartered, so Loar-signed mandolins rarely show any silk, and since the Loar-signed F5 is the standard by which all others are judged, it must be bad for a mandolin top to show silk.

  13. The Following 2 Users Say Thank You to sunburst For This Useful Post:


  14. #9
    Registered User John Bertotti's Avatar
    Join Date
    Oct 2002
    Location
    SD
    Posts
    3,537

    Default Re: Finish Issues

    I lo e ray fleck and think it looks very cool! You guys are amazing with your knowledge!
    My avatar is of my OldWave Oval A

    Creativity is just doing something wierd and finding out others like it.

  15. The following members say thank you to John Bertotti for this post:


  16. #10
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    3,168

    Default Re: Finish Issues

    Quote Originally Posted by John Bertotti View Post
    I lo e ray fleck and think it looks very cool! You guys are amazing with your knowledge!
    I thought OP was talking about the few tiny white dots in the last pic of top... ray fleck is natural feature.
    Adrian

  17. The following members say thank you to HoGo for this post:


  18. #11
    Registered User John Bertotti's Avatar
    Join Date
    Oct 2002
    Location
    SD
    Posts
    3,537

    Default Re: Finish Issues

    Im on my phone but in the last pic I see what looks like glue along the binging but when I blow up the pic there are a few tiny lighter spots kind of in the darker area is that what you mean @Hogo? And Micromesh is a great product. I used to work for them as a slitter printer and later I mixed some of the abrasives for the sanding pads and sheets. A fun place to work and the people I worked with were great!
    My avatar is of my OldWave Oval A

    Creativity is just doing something wierd and finding out others like it.

  19. The following members say thank you to John Bertotti for this post:


  20. #12
    Registered User
    Join Date
    Oct 2015
    Location
    Howell, NJ
    Posts
    246

    Default Re: Finish Issues

    I see what you are talking about. I will take a closer look. It may be glue or the tape I used to cover the white binding may have overlapped a bit. I found a couple of spots like that on the back.
    Bob Schmidt

  21. #13
    Registered User
    Join Date
    Oct 2015
    Location
    Howell, NJ
    Posts
    246

    Default Re: Finish Issues

    Thanks for the help. Your suggestions worked.Click image for larger version. 

Name:	SunburstIssues - 1.jpeg 
Views:	42 
Size:	138.9 KB 
ID:	201246
    Three coats of shellac to seal it and I thought I was home free until I looked closer and I apparently sprayed a bit too heavy around the neck heel and some of the color ran. So more redo is in order. Boy is finishing fun!
    Bob Schmidt

Posting Permissions

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