Sun tanning your instrument

[Húslař]

I show examples here:

http://www.maestronet.com/forum/index.php?/topic/328485-janitos-bench/page-6#entry717308

 

Also nice, but in my eyes the power of nature looks better (slower but priceless and most deeply).

[Janito]

I show examples here:

http://www.maestronet.com/forum/index.php?/topic/328485-janitos-bench/page-6#entry717308

 

 

Also nice, but in my eyes the power of nature looks better (slower but priceless and most deeply).

 

Did you realise that the left and middle photos are of the same violin taken seconds apart in different lighting conditions.  It shows that single photo comparisons can be very misleading when judging colour.

[Michael.N.]

'  seems to be much faster than my uv tanning booth '

~ It's not faster if your 'tanning booth' is well equipped with bulbs. 

' I did once put a violin out in strong sun that I had just varnished with a SPIRIT varnish, and in moments it started to blister '

~ That's quite unlikely to happen. 

 

Happened to me with spirit. Big blisters, bubbles. Presumably the alcohol trying to flash off. It was touch dry before I put it in the sun.

[Húslař]

Huslar, I too love the look of the maple.  How did you keep the oil varnish from soaking in the maple flames.  One coat looks very smooth.

 

Berl Mendelhall,

under this first coat is ground from clear varnish which was rubbed into wood. I used here my new varnish without solvents - You certainly remember the topic of David Sora about this types of varnishes - if You are still angry at me, I am sorry...  

[Húslař]

Did you realise that the left and middle photos are of the same violin taken seconds apart in different lighting conditions.  It shows that single photo comparisons can be very misleading when judging colour.

 

I will make some photos in another angle and light - at the end of week.

[Michael.N.]

Beautiful ground colour Huslar!

 

Lovely colour, I'd be tempted to call it done, doesn't need any more!

[Jim Bress]

I don't tan in the sun because I've been told that it reduces the luminosity of the wood. You'll get less of the holographic effect of the flames as we'll. The tanning will make it easier to control the color, though, so it spends on where your priorities are.

I do use sun for drying varnish, and I only leave it outside in 50-75 degree weather. Beyond that I leave it n a window indoors with a reflective surface behind the instrument. We don't get dry weather in the summer, but I wouldn't leave it out below 35%RH. This summer was extremely humid and I regret not dehumidifying the shop. I had some issues with the instrument I made during that period. Not sure the exact RH, but I think it hung out around 70%-80% for a few weeks.

This makes sense to me.  Excessive tanning will certainly dull the wood.  Is there evidence that moderate tanning reduces the luminosity and holographic effect under varnish?

 

Thanks,

Jim

[MaestronetLurker]

This makes sense to me.  Excessive tanning will certainly dull the wood.  Is there evidence that moderate tanning reduces the luminosity and holographic effect under varnish?

 

Thanks,

Jim

I'm not sure how much tanning you can do before it impacts the luminosity. I thought Joe Robson commented about this somewhere. Perhaps he has an answer.

[Michael_Molnar]

Colour on maple from UVA tubes is more yellow than colour from sun. 

If you use hot water you can actually wash some of the colour off too...

as I found out when washing off some glue on a back that had been tanning. 

San tanning is better since it's cheaper and less toxic. 

Hard to make direct comparisons with sun and UVA tubes when 

working with time and colour, because it depends how many tubes

you use, how many watts they are, how much UVA is in your sun

(more if you live in the Himalayas) and how much colour you actually want. 

I have 20 tubes which put out lots of light, some instruments left in the room

for a month using 8 hours light per night come out golden coloured. 

Not good to put ribs in hot light rooms when they're off the forms, they 

will distort badly becoming skinny. Things generally shrink a bit too...

fingerboards and necks need to be re-finished etc. 

Generally, it's all a bit of a pain and if you can avoid it all then do. 

 

Why does sun tanning give a different color than a UV box? I too notice a red color that develops in the sun. I suspect it is something in outside fresh air that isn't found in the UV box. Nitrous oxide?

[Jim Bress]

Why does sun tanning give a different color than a UV box? I too notice a red color that develops in the sun. I suspect it is something in outside fresh air that isn't found in the UV box. Nitrous oxide?

Does a UV box also produce ozone?  It may be the absence of something that makes the difference.  Just postulating.

 

-Jim

[Michael_Molnar]

Does a UV box also produce ozone?  It may be the absence of something that makes the difference.  Just postulating.

 

-Jim

Ozone is made by extreme UV shorter in wavelength than 240 nm. The UV lamps luthiers use do not emit that kind of dangerous UV. They emit above ~300 nm.   You need to use "C" type lamps that are clear and made of quartz. So, yes it may be that the red color is due to ozone. Nitrous oxide is made mostly by agricultural fertilizers. 

[Don Noon]

I would be interested to hear an explanation of the optical cause of UV:

-dulling the wood

-reducing luminosity

-reducing holographic effect.

 

There are also others who apparently think the opposite is true. 

 

I have some ideas, but would like to hear other explanations first

[~ Ben Conover]

Mike, one of the scroll blocks I got recently was so old that it was dark grey / brown, 
and the colour went right into the wood. That colour is not something you get with UVA
tubes. As said, you can wash off the effects of UVA tubes slightly, but not with 30 years
exposure to the air. There are technical terms for oxidation that I can't remember. 

I don't see the point in making the wood so dark but for competition level antiquing
that's pretty much what you'd have to do. Makes zero difference to the player of course.
Then there's the issue of the wood structure, if UVA and chemicals make it less flexible, 
I think they do. 

 

[Michael_Molnar]

Thanks, Ben. I have no idea what happened to that scroll block, but I have seen some maple blocks and wedges develop a red/orange discoloration that goes well below the surface. I remember when I did not plane away enough material at the glue line of a heavily tanned wedge. That plate turned out to have a stripe running down the center. Bummer! I treated it with some bleach, and that helped. 

 

FWIW, I no longer tan my violins either in a UV box or in the sun because, I think, this reduces the grain contrast. Nevertheless, I feel that there are many ways to make a great looking violin. Look at Húslař's nice results. Pick your poison! 

[Marty Kasprzyk]

Here.  All the time.

 

 

I definitely do not recommend what I have done on occasion on the cooler days here to make varnish dry faster... adding solar reflectors.  It is probably my aerospace testing background, where you usually test things far, far beyond where they will ever be used.  I figure if it doesn't fail at 145 F (observed surface temperature), it will probably survive most things later.  And I'd rather have something go wrong here than there.

But, like I said, I'm not recommending this to anyone.  My processed wood is also far less sensitive to this type of abuse.

I'll try putting a large parabolic mirror reflector behind one of my violas.

[~ Ben Conover]

Padding says in the varnish book that tanning should be kept to a minimum. 
I think he had a good handle on things. 

[Don Noon]

I'll try putting a large parabolic mirror reflector behind one of my violas.

 

A propane torch is easier, and would have the same beneficial effect.

[Dwight Brown]

Are light boxes made with built in fans and air filters?  I would think that keeping the varnish drying area free of dust would be important.  Kind of reminds me of some drying boxes we had for roll film back in the dark ages.

 

I tried to look up some UV tubes and such on my school computer, all the sights were blocked because the software thought I was trying to grow something herbal :-)

 

 

DLB

[franciscus]

Just my two coins here: the radiation from the Sun is much more complex than the radiation from the tube (any tube). Furthermore, if the thermal part of the spectrum is something that causes the problems, move the target (violin) to the shadow.

[Peter Lynch]

Padding says in the varnish book that tanning should be kept to a minimum. 

I think he had a good handle on things. 

Ben,  I lent my copy out so I do not have it to reference right now, but I thought much of his concern with tanning related to having to use bulbs that had higher uv B radiation levels and he was against that for safety reasons.  I could be remembering incorrectly though.....  

[Dwight Brown]

One of the best things I have learned about the EM spectrum lately was if the entire spectrum was represented by a line from New York to Los Angeles visable light would only be about the width of a dime !   It's amazing how small a portion we can see.

 

 

DLB

[tango]

(...) Furthermore, if the thermal part of the spectrum is something that causes the problems, move the target (violin) to the shadow.

 

 

 

 

(...) Now I hang the instrument early in the morning and in the last hours, always checking the temp of the wood.

I saw that in the middle shadow at the open air also we achieve some colour.

(...)

 

 

Hi Franciscus

 

I see we are agree.

My assert it´s only a feeling without any scientific prove.

 

Regards

Tango

[Michael_Molnar]

FWIW, Brandmair & Greiner (p. 20) make a compelling case that Stradivari did not sun tan his instruments because this is a very slow way to darken wood naturally -  too slow to fit in with what we know about Stradivari's production rate. 

 

Mike

[Conor Russell]

Is enough known about Strad's production rates to be able to draw a conclusion? Without dated documents that can be matched with instruments, and some dendrochronology thrown in, I can't see how.

I don't see the Strad sbop as a well oiled factory. It produced just 1200 (?) Instruments in a long lifetime , with sons and employees , and there were some 80 instruments left unfinished or unsold at the end.

So why shouldn't instruments have had six months or a year at least to warm up before varnish? Especially those made from young wood. I think that people back then were far more accepting of the time it takes to finish work.

[~ Ben Conover]

Peter, yes. 

Conor, disagree. 

Mike, good point.