I've just received a Martin Auditorium 000C-16GTE for repairs. It's the first instrument that I've seen with a MICARTA fret board and bridge. Many factory guitar makers now leave 1/8" of finish (to save on the production costs?) around the top plate's (bare wood) gluing area which gives the appearance of a lifting bridge. With less bonding area, the bridges often do begin to lift. Having little experience with this man-made substance (MICARTA), I am wondering what characteristics it has:
Does heating (for removal) warp or melt it?
What glues are compatible with this?
What are the working characteristics as a fret board or bridge?
(I have found that bridge pin holes are harder to ream)
I'm on a fact-finding mission BEFORE risking damage to the existing (micarta) bridge. It's a customer's instrument, not one that I can experiment with. I figure I'd better do the research before any more come through the door. This bridge has not yet begun to lift, so I've recommended that the owner just keep an eye on it for now. I would most likely replace it with ebony. Those who've engineered the product should have some answers about how it behaves and how to use it.
Thank you, Frank. I am hoping that someone has had some experience with micarta that they are willing to share here, since such materials are becoming more common in the building of musical instruments. When engineers introduce new products I believe that they are required to also offer information pertaining to its usage and limitations in industrial use, etc, including test results. Perhaps that's what I'm hoping to find here.
I'm a bit short on technical expertise for this application of Micarta. It's a substantial material and it has been used for fingerboards before Martin got into it. Stelling made a number of high end banjos with the stuff, calling it "ebonol," I believe, but later they abandoned it. I feel a bit uneasy about the stuff from the standpoint of long term adhesion to wood, but I have no evidence for that worry.
I've done work on several Martins with micarta fingerboards and bridges. In answer to your concerns, it will melt/bubble/peel if exposed to high heat. Lower temperatures for somewhat longer times seem to work best with it. If you do create any ripples or gray areas (I don't know why it does that) it will level/polish back up nicely with 400 grit.
I've used both hide glue and LMII's white glue with it and have experienced no problems with adhesion. It appears to be a bit harder to work than the average piece of ebony but that didn't pose any problems either. It also resists chipping when refretting.
I've decided that I like it for fretboard material but dislike it for bridges and given the opportunity I'll replace the bridge with ebony. There may be some damping going on there with micarta as ebony replacements seem to provide tonal qualities that I prefer.
I know this doesn't help the discussion, but I DON'T like that material AT ALL. I really can't understand how a great factory, as Martin is, that's famous for its overall quality instruments, can decide to use a sort of plastic for so important parts as bridges and fret boards. How much more should the same guitar cost using hard woods as ebony or rosewood?
I don't have a piece of micarta for testing to listen to its acoustic properties, although, in cleaning glue from the fret board end, I found that it seems like a somewhat flexible hard plastic. Flexibility generally indicates a deadening of sound. In my last visit to the Martin factory, I was stunned when the guided tour began in a large room where they were putting together guitars with formica (?) backs and sides with aluminum tops. Aluminum is acoustically sound, but quite cold to the touch. Explanations went the route of a growing scarcity of woods. The resultant sound was not pleasing to the ear. Most guitar factories' bottom line seems to be profit as cheaper materials are hyped as improvements at the actual expense of structural integrity.
Are we talking about current use of this material? In my mind marcarta was a WWII substance primarily used for electrocinics work - it is mica filled phenolic (bakelite) - and was popular for high frequency/low loss vacuum tube bases and plugss. I pretty much thought that micarta was being phased out due to some environmental concerns with handling the formaldehyde (also in the tube production world high quality mica is harder to find but since the stuff in micarta is ground into a dust that may not be of important.) I used to make period reproductions which led me to make period finishes/paints which let me to make "period glitter" (well not really) - shellac with ground mica suspenced in it. Looked much nicer than the plastic!
While I know I'm spinning off the track the while idea sorta spins me off the track. Again, are there current models and what are they so that I might research them. (and why the f.....bother to make 'em?).
The serial number on this Martin is 838449, which should place it at about 10 years old (my reference books are older than that). Your "high frequency" description makes me think of the man-made Tusq material that's currently being offered for instrument builders and repairs. I am impressed with its acoustic properties: (when dropped, it makes a "plink" -like crystal being tapped), although I would also like to know more about it.
In all fairness, one must also note that most exotic woods are toxic in one way or another. I've heard players complain that ebony hurts their fingers. As a veteran environmentalist, I am concerned about the possible presence of formaldehyde in micarta and would like to know if, in fact, this has been phased out...wondering how it ever got 'phased in' without safety testing. Of all the petitions I've seen (and signed) about saving the old forests, I rarely read of efforts to plant or replant trees. Hopefully this is happening. (good news always travels more slowly than bad).