jdowning
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Chemically Treated Maple for Fingerboards?
Forum member spyblaster recently raised a question about whether or not Maple might be a suitable wood for fingerboards.
The ensuing discussion has gone a bit off track so I thought that it might be best to start afresh with the original question.
Although even hard Maple is thought to be a bit too soft for fingerboards it was noted that some guitar fingerboards are made from Maple that has been
impregnated with Polymethyl Methacrylate in a vacuum chamber. The Acrylic is forced into and fills the wood cells so that after being cured with heat
creates a wood/plastic composite that is considerably increased in hardness - and so suitable for fingerboards.
Preparation of this material - due to the costly specialised equipment and 'know how' required - is beyond the practical reach of most luthiers.
However, all may not be lost for a luthier wanting to obtain and try, at quite reasonable cost, small quantities of chemically impregnated Maple (or
Walnut and other relatively soft woods) for fingerboards.
The American company 'River Ridge Products' specialises in supplying chemically impregnated wood blanks for pen making under the trade names
'AcryliWood', 'Dymondwood' and 'Dymalux'. 'AcryliWood' is natural wood dyed and stabilised with an Acrylic resin. 'Dymondwood' and 'Dymalux' are built
up from layers of veneer saturated with Phenolic resin and then compressed under high pressure.
http://rrpwhite.com/wood-stabilizing
Pen blanks are small in size but the company can supply larger treated wood blanks measuring up to 2.25 inches X 2.25 inches X 30 inches in length.
They also offer to impregnate small samples of wood (supplied by customers) for customer evaluation for a fixed fee of $10 (US customers) or $20
International - including shipping. They also offer custom treatment of customers woods
I do not know if their products have yet been tried for oud or guitar fingerboards but the stuff would appear to be very hard and abrasion resistant
(carbide blades recommended for sawing). It can be glued to other natural woods with epoxy glue.
The larger sized blanks could be cut into fingerboards. Cost then would be significantly lower than equivalent sized blanks of natural Ebony or
Rosewood fingerboard material offered by the major luthier supply companies.
Worth investigating further perhaps?
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jdowning
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These might also be a good materials for making oud tuning pegs?
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jdowning
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Note for Canadian and American customers. As a convenient source of supply, Lee Valley tools of Ottawa carry pen blanks of stabilised and dyed Maple
and 'Dymondwood' blanks. The latter are the stripy versions (straight grain, uniform colour material would generally be best for luthier work) but
both would be useful for limited trials to determine the properties and workability of the materials.
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jdowning
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Some of the figuring in the dyed solid maple 'AcryliWood' is 'gem like' in appearance so might also have an application - when cut to veneer thickness
- as decorative inlays, perhaps also for making some really unusual rosettes?
I have been in touch with the company with a question concerning the minimum thickness of blanks prior to treatment so will report further once I have
a reply.
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jdowning
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This morning I spoke to Stephen White owner of 'River Ridge Products' in the U.S.A.
Their particular 'niche' in this market is to supply small quantities of their products to custom craftsmen/women - pen, knife, bow, jewellery makers
etc.
He confirmed that his company produced 'Acryliwood' from untreated natural wood by pressure impregnation with a methyl methacrylate resin formula. For
dyed woods the dye is used to colour the resin but as the dye does not attach to the cell walls of the wood under treatment some slight bleeding of
the dye may occur in service if, for example, there is prolonged contact with the skin as with a wooden bracelet. In these circumstances a protective
coating is recommended to seal the dye into the wood.
For thin fingerboards (2-3 mm thick) or thinner veneer for inlays, these should be cut (bandsaw) from a blank of minimum thickness of 1 inch. Due to
internal stresses in the natural wood - particularly in highly figured, twisted grain material - there may be some bowing or cupping of the veneers
cut from the blank. However, and in this event, there should be sufficient flexibilty to allow flattening of the veneers when gluing. Removal of saw
marks and final finishing is done with abrasive papers (i.e. sanding).
Most wood species can be treated - except for oily woods - so there is scope for avoiding dyeing (if that is a potential problem) by choice of natural
colouring in wood species. Open grain wood species or 'spalted' woods are easier (less costly) to treat than close grained woods.
"Dymondwood' is purchased from another manufacturer for processing and resale. This material is laminated from 1/16" (1.5 mm) thick Birch veneer,
dyed, impregnated with phenolic resin and cured under high pressure and temperature. It is essentially a high grade dense plywood. It is a harder
material than Acryliwood. The possibility of dye 'bleeding' in service is also something to be taken into account - making this material less useful
for instrument applications perhaps - unless a plain white Birch fingerboard is desired.
Relative hardness of either product - compared to natural wood - is at present undetermined. I shall, therefore, purchase a couple of pen blanks from
Lee Valley for further evaluation.
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fernandraynaud
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Great, especially for luthiers, or for those of us who make our own fingerboards. Did you learn if the technique was to use an initial vacuum, or
rather start from room pressure?
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jdowning
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They impregnate the wood with both heat curable resin and dye under a multiple cycle pressure process in order to force the chemicals through the
volume of the wood. I understand that the number of pressure cycles required depends upon the cell structure of the wood - fewer cycles for softer
areas and open grain or spalted wood, more for close grained harder woods.
They confirm that the dyes will only penetrate the outer layer of wood if applied at ambient atmospheric pressure.
One interesting product in the Acryliwood line is 'NuEbony' - Walnut ebonised using an inert (insoluble) pigment in the wood to turn it a deep black
like ebony - difficult to distinguish from 'Gaboon Ebony' but easier to work than the real ebony.
They previously advertised the material in pen blank sizes only but said that they plan to have larger sizes available.
Will check maximum blank sizes possible for this material. Again hardness yet to be determined from a test on a blank.
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jdowning
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'River Ridge Products' has advised that they have decided not to expand the 'NuEbony' line - from the pen blank size - due to the high capital cost of
the equipment required - so fingerboard sized blanks are not and will not be available in the future. Too bad!
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jdowning
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Ordering some stuff from Lee Valley yesterday I included a chemically dyed and stabilised natural maple wood pen blank for hardness testing, dye
penetration, machinability etc. to see if the material might make good fingerboards.
The Lee Valley pen blanks of this type (sourced from the U.S.A.) have been stabilised by resin impregnation under pressure (with Acrylic resin?) so
is very likely to be similar to 'Acryliwood' mentioned earlier being sold by 'River Ridge Products'.
'River Ridge Products' can treat Maple and other woods - not only in pen blank sizes - but in dimensions suitable for making fingerboards (either dyed
or in natural colour) although this unfortunately does not apply to the product 'NuEbony' that is only available in pen blank dimensions.
I expect to receive the pen blank early next week so will report the results of testing here for general information and consumption. Hopefully the
results will be promising (as I expect them to be given that some guitar manufacturers are already using resin impregnated fingerboards).
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jdowning
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I have just received the pen blank from Lee Valley for testing (the usual good service, 3 working days delivery from ordering).
The blank is stabilised and dyed (black) Maple Burl wood cat.# 88K79.12. It measures approximately 127 mm X 20 mm X 21 mm.
Its mass (weight) is about 61 grams so its specific gravity is about 1.14 similar to a dense tropical hardwood like Ebony.
These dimensions are only approximate at this stage because - as can be seen from the attached image - the blank is not only in a rough sawn finish
but has distorted (bent) during the dyeing and stabilising process. Potential distortion is something that must be allowed for when providing wood
blanks to 'River Ridge Products' for custom stabilising with acrylic resins. The rough sawn finish is likely to facilitate penetration of the dye and
resin under pressure.
As can be seen the black dye is quite dense. However, this will be further evaluated by cutting the blank to determine uniformity of color and depth
of penetration.
The first step will be to cut a sample piece from the end of the blank that will be sanded to uniform dimension and a smooth finish for accurate
measurement of density and hardness testing.
This stuff is said to be hard and brittle (like Plexiglas I suppose - another acrylic plastic?) so I will cut the blank using a metal cutting band saw
at slow speed as it will likely dull the carbon steel blades (and overheat the blank material) of my woodworking bandsaw.
I will then cut the remainder of the blank longitudinally (to determine if there are any built in stresses) and then turn a lute (oud) peg from what
is left (using HSS or carbide lathe tools). I will also see how the material will glue to untreated wood (using epoxy) useful to know if a
fingerboard, or peg head, or decorative inlays are to be made from this material.
More to follow
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jdowning
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A cube measuring approximately 2 cm on each side has been cut from the blank using a metal cutting bandsaw. The saw easily cut through the material
without a problem except for some minute chipping of the edge where the saw 'broke through' the blank.
For those who do not have a power saw cutting might be done by hand with a metal cutting hacksaw fitted with fine tooth blade - a lot easier and
faster than cutting say, mild steel.
The sample 'cube' was then squared and made flat on all sides by rubbing first on a coarse 80 grit open grain Garnet paper (sand paper) and then
smoothed with finer grit papers. The material sanded easily although tended to clog the finer papers. Two faces were then finally polished to a mirror
finish using a fine abrasive (rotten stone).
The polished faces of the cube (side and end grain) revealed the figuring and cell structure of the original untreated wood. The black dye appears to
have penetrated to the full depth of the pen blank although the colour is not a dense black but what might be described as Slate Gray. The overall
appearance resembles gray marble - rather attractive.
The apparently open cells visible in the macro images seem to be mostly filled with transparent resin when viewed at an angle.
The fine scratches visible in the macro images are sanding marks that were not removed in the final polishing.
Any 'flaws' such as open cells on the surface may easily be filled with 'super glue' or ground out and filled with epoxy or super glue before final
sanding and finishing (as recommended by 'River Ridge Products')
So, the material is quite easily worked although care must be taken to avoid high spped power tool operations that might overheat and fracture the
acrylic resin. My first impression, however, is that the material is a lot easier to work than pure acrylic plastics such as 'Plexiglas' that are
quite brittle.
Next to measure the density of the cube that can provide a measure of relative hardness (compared to natural untreated tropical hardwoods) and to run
some comparative tests with a low cost cone point impact hardness tester.
Looking promising so far.
[file]26266[/file] [file]26268[/file] [file]26270[/file] [file]26272[/file] [file]26274[/file] [file]26276[/file] [file]26278[/file]
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jdowning
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The density of the material under test is calculated by measuring the volume of the cube and its mass. The density is then mass divided by the
volume. I prefer to measure density in the old c.g.s. units of grams/ cubic centimeter as this then is also the specific gravity (the density of the
material compared to that of water - water having a density of 1 gram/cc).
To calculate the volume of the cube the sides were measured to an accuracy of .01 mm using a Starrett micrometer gauge. The calculated volume is 8.94
cubic centimeters.
A mini digital scale was used to measure the mass of the cube. This one measures to 0.01 gram but others are available that measure to a milli gram
(0.001 gram). These scales are quite inexpensive costing less than $20 on Ebay. Designed for the jewellery trade they do not measure to laboratory
standard but are more than adequate for this application and for my work on instrument strings.
This scale cost about $15 delivered and comes with 10 gram and 100 gram calibration masses. Calibration is required because of the variation in the
acceleration due to gravity in various locations on earth. Once calibrated (an automatic function for this scale) the digital output measurement is in
grams (units of mass) rather than Newtons (the International Standard units of weight or force). (All legal commercial spring or load cell scales are
calibrated in this manner to indicate mass - although we all still call it 'weight').
So the measured mass of the cube is 9.43 grams and calculated density of the material is 1.055 gm/cc. Its Specific Gravity is therefore 1.06 - a
dimensionless number.
As the specific gravity is greater than that of water the cube will sink in water rather than float as it would have done before being stabilised with
acrylic resin.
Knowing the S.G. of the stabilised wood it is then possible to make a reasonable estimate of its hardness from data provided by the US Forestry
Research branch (see attached graph). It can be seen from the graph that the Janka side hardness of the sample is about 3,800 pounds force derived
from a specific gravity value of 1.06 - about equivalent to the denser varieties of African Ebony.
Next to verify the relative hardness against some specimens of tropical hardwoods using a low cost cone point hardness tester subject of this recent
development topic on the forum.
http://www.mikeouds.com/messageboard/viewthread.php?tid=13647
[file]26280[/file] [file]26282[/file]
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jdowning
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The cone hardness tester gave an indent diameter of 1.4 mm diameter, side grain, X10 impacts for the test cube,
This compares with tests on untreated wood samples as follows:
African Ebony 1.35 mm dia.
Cocobolo 1.45 mm dia.
Brazilian Rosewood 1.59 mm dia
East Indian Rosewood 2.18 mm dia.
Birds Eye Maple 2.0 mm dia.
Here the harder the wood the smaller the indent diameter. So it can be seen that the the hardness of the acrylic stabilised sample is somewhere
between the hardness of the Ebony and Cocobolo wood samples - given the wide ranging Specific Gravities (and so hardness) of each species and the
difficulty in precise measurement of the indent diameter.
Interestingly the stabilised wood sample produced a clearly defined indent without surface fracture due to the impact loads - unlike the more brittle
Cocobolo and Brazilian Rosewood samples.
[file]26307[/file]
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jdowning
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To finish tests on the 'Lee Valley' Acriliwood type sample, the distorted blank (curved longitudinally) was cut through the curved portion in a
straight line in order to determine if there might be any residual stresses in the blank. The cut piece remained straight after cutting without
distortion.
This time the sample was sawn on a woodcutting bandsaw with a coarse 4 tpi blade - and slow feed - without any apparent problem. The rough sawn
surface was then smoothed on a power sander using only light pressure of the blank on the sander. It is very easy to overheat the material with too
much pressure (and presumably damage the materias by melting the acrylic plastic saturating the wood cells?)
The material also responds well to levelling by hand on a sandpaper block - slower, but with no danger of over heating.
The fine dust produced by sanding tended to clog the sandpaper so an open grain sandpaper paper is best for the purpose.
I am not sure if the dust is toxic or not so - as with any wood species - best to use a respirator (and dust extractor) if a lot of sanding is to be
done.
The rough sanded surface was finished smooth with a cabinet hand scraper without problem - the scraper producing fine shavings as if working untreated
wood (see attached image)
A fine finish may also be produced by hand sanding with increasingly fine grit abrasive papers.
The final polished finish is shown in the attached image - similar, in this case, to polished black marble.
Of course acrylic impregnated wood may be left undyed natural or dyed in a variety of colours. The wood itself may be plain grain or spectacular grain
figure. So the scope for an unusual attractive hard fingerboard material would appear to be wide.
I do not have time to test how the impregnated wood might be used for peg making. However, as the blanks are intended for pen making there would seem
to be no doubt that the material will turn well on a lathe.
I am not sure if a peg made entirely from acrylic treated wood would be successful. However, a peg made with a tapered shank of wood with a separate
peg head turned from Acryliwood - glued to the shank with epoxy glue - might be, in appearance, a spectacular alternative to a conventional oud peg?
All limited only by the imagination of the luthier.
[file]27053[/file] [file]27055[/file]
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