What is an appropriate finish for a marimba bar? - (Q from Richard.Evans)
-----Original Message----- From: Richard.Evans Sent: 29/08/07 4:17 PM To: firstname.lastname@example.org Subject: What is an appropriate finish for a tone barDear Jim,
I'm now trying to make Jon Madin's bigger diatonic marimba (3.5 octaves). I'm using "Tasmanian oak". It is a light coloured wood and for those who might want to use it , it appears to be at least two species of tree. (E. Regans and E Obliqua "mess mate"). I found this out when I was selecting the planks and found that identical sized pieces were obviously different in weight. I then, of course, chose planks of the same density ( the heaviest one). Any way I'm now staining them before carving with Cabots "Jarrah" stain which looks nice but a darker stain would look even better. I also made some bars from Fijian Mahogany which has a nice orange-red colour but I found it doesn't ring as long as the Tasmanian oak.
My question is what kind of varnish or oil should I finish the bars off with. I've got some marine grade "estapol"-kind of varnish which is wonderfully tough and adds a slight golden tint. I was also thinking of Danish Oil for a satin finish. What is you experience and what do other marimba makers do? Oil, varnish, only stain or do nothing???
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Dear Richard ...
If it was me, I would avoid using the estapol. It does provide a lovely gloss finish, and means less in the way of future maintenance, but in the long run there is likely to be problems. My own concert marimba is finished with an estapol, and looked extra fabulous for a year or maybe more. Over the years the edges of the finish have cracked though which looks terrible and the gloss has faded somewhat. Admittedly I gave it a head start by working on a piece that required playing over the edge of the bars with the shafts, but it has certainly worsened quite a bit since. The problem is that refinishing now would mean sanding back the bar faces, which makes the bars perilously thin, and means they all need to be completely retuned from scratch. I would dearly love to go back to a natural oiled finish now if it was't going to be so expensive! (almost 5 octaves of bars professionally tuned including all the overtones!) if you DO decide to go with an estapol finish - bear in mind that the extra mass will effect tuning to a reasonable degree - depends on the bar and how fussy you are. On a professional instrument, the tuning would be unuseable if estapoled after tuning - this means .... Tune the bar in a basic way, but finish the bar before the final tuning.
Stained is fine - won't effect anything - then oiled finish. I use a furniture oil like marveer or scandanavian teak oil. You want to reapply it two or three times a year to keep the bars healthy - stop them drying out. This type of oiling will not effect the tuning at all.
My concert marimba has padoak bars - much harder and denser than "Tasmanian oak" (a bit of a trade name that the hardware stores use I suspect, which could encompass a few species with "close enough" characteristics for the builder, but not necessarily the instrument maker) With the softer timber I suspect the estapol is even more likely to crack, as there would be greater surface flexion at the contact point when hitting the bars.
Hope this helps mate...
answers by Jim MCCarthy - 01/12/2005
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