Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Crack Hiding Glue?

Discussion in 'Luthier's Corner' started by IronSpatula, Jul 18, 2005.


  1. Some time ago, I read an advertisement in a woodworking supply catalog for a super-thin, crystal clear glue that could fill cracks and dings in gloss finishes so effectively they became invisible. It was supposed to be so thin that when applied to a crack it would wick in and displace all the air, making it invisible, and then set completely smooth and flat at the top of the crack, making any buffing pretty much unneccesary. The only problem is I can't remember the name of this stuff, and I haven't been able to find anything like it locally.

    Any ideas?

    Or was I hallucinating?
     
  2. Bass Kahuna

    Bass Kahuna

    Dec 3, 2002
    West Lafayette, Indiana
    Luthier, Custom Builder
    Sounds like you're describing regular old super glue, which is what a lot of luthiers and guitar techs use for just this type of thing (myself included).

    Stewart MacDonald (http://www.stewmac.com) sells several different types of these kinds of super glues, however, regular old super glue from your local hardware store works well too.
     
  3. nateo

    nateo Schubie Fan #1

    Mar 2, 2003
    Ottawa, Ontario
    I like to by my glue at a local hobby store. They sell it in much larger bottles and the price is (per ounce) significantly less than at my local hardware store. They've also got a nice selection of thicknesses (I usually stick with superthin) and hardeners.

    As most people on this forum will tell you, look for cyanoacrylate (or CA). It's the main ingredient in superglue and it's what the hardcore folks at the hobby store will call it. Also, if you're in need of a crystal clear finish stay away from the hardener. It tends to cause the glue to go cloudy.

    -Nate
     
  4. Interesting that both of you recommended cyanoacrylate.

    My current project is repairing and cleaning a '79 Washburn Vulture. The major issue with this bass was a headstock cracked and bent forward just above the neck, barely still attached. I glued and clamped it, then reinforced it by putting a wood screw (under the truss rod cover) perpendicularly through the break. That went smoothly, and the headstock can now stand the pull of the strings without problems. However, there is still a thin but visible crack in the poly finish on the back of the neck.

    I went to my local Woodcraft store a few days ago to see if they had anything to fill the crack with, and the guy there also said CA was my best bet (outside of refinishing the area, which I'd rather not tangle with). So I got the slowest curing CA they had (Hot Stuff "Special T"), thinking that a slower set time would allow deeper penetration. When I applied the glue to the crack, it filled what little gap there was on top and dried perfectly clear, but didn't wick in deep or really do anything to hide the crack.

    I'm not really disappointed since this bass is pretty beat up anyway. The crack on the back of the neck is just one of many "character marks" now. However since this glue did not produce the result I was seeking I started this thread, trying to find out if there was something better I could use in the future.

    What do you guys think? Was the CA I used just not thin enough? Or was the crack too small? Or did I apply it improperly?
     
  5. nateo

    nateo Schubie Fan #1

    Mar 2, 2003
    Ottawa, Ontario
    The superthin CA wicks in an amazing amount. The actual instructions are to clamp your parts and then apply glue to the seam. I've seen penetration on the order of inches between two blocks of wood clamped together.

    I'm betting the CA you came home with was a bit thicker (often called "gap filling") and that's why it didn't soak in as much. It could also be just a brand difference, who knows?

    -Nate
     
  6. Bass Kahuna

    Bass Kahuna

    Dec 3, 2002
    West Lafayette, Indiana
    Luthier, Custom Builder
    It sounds like the CA did it's job. Often, to fill a crack you have to apply more than one "coat", allowing each one to dry first.

    btw... you'll never "hide" the crack or make it invisible to the eye. Even a re-finish won't completely hide it unless you go over it with a solid color. Best you can do is to make it structurally sound and to then make it where it is smooth to the touch, but you'll never reall hide it.

    Also, hopefully you used a wood glue to repair the crack and not CA to repair the original crack itself.
     
  7. Thanks for the info, guys. I really appreciate it.

    Of course. :D