Omar Al-Mufti - 6-5-2015 at 10:47 AM
Dear members,
I need advice please.
What are the available methods for finishing the bowel ....without any type of lacquer or shellac?
I would like to keep the natural wood color, pores and grains. Something very thin rhat just seals the pores and protects the wood. Probably oil or
wax finishes if they have no negative effect on sound
Thanks
Omar
Brian Prunka - 6-5-2015 at 12:48 PM
A polymerized oil like tru-oil is easy, fairly non-toxic and works well.
Omar Al-Mufti - 6-5-2015 at 01:31 PM
I heard oils are not good for music instruments
jdowning - 6-6-2015 at 04:04 AM
Tru-oil like other similar hand rubbed finishes (e.g. 'Danish' oil) are thin penetrating varnishes that may be easily applied with a cloth (applying
thicker varnishes with a brush is a more skilled job). The 'oil' refers typically to either linseed or tung oil to which varnish is added resulting in
a thin the mixture that can be applied by wiping with a cloth. These finishes are polymerising i.e. they will quickly dry to a hard finish. Raw
linseed oil will never dry without being treated by heat, Ultra Violet light (or sun light) and chemicals that promote polymerisation. Linseed oil
based brushing varnishes include resins in their formuation to provide extra 'body'.
Linseed oil based varnishes have been used on musical instruments for centuries. Violin makers cover the whole of the instrument with a brushed on
varnish - oud and lute makers should only use varnish on the bowl. Penetrating varnishes or oils should not be applied to sound boards of ouds or
lutes as it will affect the acoustic performance. Varnish (or wax) applied to a bowl will not have any influence on the sound.
Note that varnishes applied directly over oily woods like rosewood or cocobolo may not dry or harden. Note also that penetrating varnishes will darken
or alter the appearance of a wood (ideally emphasising the beauty of a wood grain)
Wax as a wood finish is usually applied over a surface that has been previously sealed with a penetrating finish and filler. Wax is not a durable
finish so needs to be regularly maintained by rewaxing.
Omar Al-Mufti - 6-6-2015 at 11:07 AM
The only thin I found here in Austria something called boiled linseed oil fast drying varnish which is made of only linseed oil and no other
additives.
Is that OK?
jdowning - 6-6-2015 at 11:50 AM
If it is the commonly available 'boiled' linseed oil of commerce it will have chemicals added to speed up drying time (still quite slow in drying and
not very good protection for wood). On the other hand it might be polymerised linseed oil that has been heat treated (not much better though I
imagine)?
I have used 'boiled' linseed oil as a 'preservative' finish on wooden garden tool handles but would not use it on instruments. The oil also darkens
wood as it soaks into the pores.
Tung oil is a better preservative for wood than linseed oil and is available as a slower drying pure, food safe product or faster drying polymerised
oil with chemical additives. Both types are available from Lee Valley Tools of Ottawa (check their catalogue on-line for information) but there must
also be European suppliers.
As with all wood finishes it is best to test the product on scrap wood before applying to an instrument.
Omar Al-Mufti - 6-6-2015 at 11:59 AM
Aha
It doesn't say anything about additives other than "seccative" .......and fast drying