Speeding up suntanning


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14 hours ago, Jim Bress said:

Let’s see. This morning before work I planed and rounded the end grain of some belly and back cut-offs down to fresh wood for the viola I’m making for test varnishing. I put the two pieces in my light box to tan. Basically trying to do things as near to how I will varnish the instrument. 

Just now I planed another cut off of the same belly and back that I will exclusively tan with the sun.   We’ll compare in 10 - 14 days. The sun tanning will be unpredictable because of rain days and the annoying habit of the earths rotation. 

  

natural sunlight tanning works sometimes but other times it can have a bleaching effect leaving the wood a dirty grey colour. Ive seen people applying a thin coat of varnish or something when tanning in sunlight and it often still tans but without the greyness/bleaching.

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On 6/1/2018 at 2:01 AM, Conor Russell said:

Hi Per.

I can't help thinking that some moisture in the wood helps, a bit like metal rusting, so I take the violin out, mist it with water, and leave it overnight occasionally. I also have a pot of water in the bottom  of the light box, although I'm not sure that it does much.

I'm pretty sure that fresher wood tans more quickly than old wood, and it develops the ripple in the flame too. If I could, I'd make my violins with fresher wood, and just hang them to season for a year in a bright place.

Exactly,

Misting with water makes a beautiful golden natural color at around 100F,

Warning, all of my wood has been repeatedly soaked and dried, it does make a big difference and is worth the extra trouble,,,,,,, so a little heat and water are of no concern to me, be careful, learning curves are not fun.

Or a faster method is to spritz a bit of dilute tannic acid in water on the fiddle exposed to the sun for a day, ,,,a bit of Osage orange wood boiled down and  the tannic acid will make a nice warm golden color for a ground. Osage orange is sold all over because it is a great dye, but it is insanely expensive at times,,, it grows like a weed throughout the Midwest, in Oklahoma and Texas the ranchers will pay you to cut it down and take it because it gets in the way of their grazing cattle. I bet not telling has some in her back yard.

In fact just boiling up most woods will give a color to wood when re applied using 2 parts hydrogen and 1 part oxygen, just concentrate it to make it stronger. Different shades can be handy to even up the natural color variations, depends on how much one wants to futz around.

Sure don't want to look like a North Dakota Norwegian girl in Jamaica in January.

Evan Viking by Marriage

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14 hours ago, Bill Yacey said:

Interesting you say this. I was thinking the same thing scrolling through the previous posts before reading your post. Strong IR will indeed darken and yellow the wood, before it's starts turning brown and beginning to char. At moderate levels, it may be controllable and advantageous.

My thinking (speculation) is that the heat of IR would bake the top few cell layers driving out (drying) any volatiles and increase surface stiffness to some degree. Maybe not. 

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And further to that, I believe it will darken the wood visually too. Years ago I baked some wood in the oven, and it tuned a nice deep yellowish brown after a few hours. I can only think this is due to the IR toasting the wood surface.

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6 hours ago, fiddlecollector said:

natural sunlight tanning works sometimes but other times it can have a bleaching effect leaving the wood a dirty grey colour. Ive seen people applying a thin coat of varnish or something when tanning in sunlight and it often still tans but without the greyness/bleaching.

Right, eventually all wood will turn gray.  I have some subjective "good enough" color in my mind that I'm looking for.  I did a sample years ago where I progressively added more tape over time to a strip of rib stock sitting in a west facing window sill.   The rate of change decreased with time to the point where there was little difference after 3 weeks.  At some point the wood will start to degrade.  I tan to what I think of as a moderate level.  For my light box I reach this point in the neighborhood of 240 hours, but will stop sooner if it reaches the "good enough" point.  

Interesting point on tanning.  A couple of years ago I did some varnish testing combinations of sunlight tanning, wet chemistry, and untreated-untanned wood on uncarved billets.  The difference between tanned and untanned has disappeared on the maple and is greatly reduced on the spruce.  These billets are stacked on a high shelf so that air passes around them but they get no direct light.  It may be that UV is providing the energy to increase the rate of oxidation and not directly tanning the wood.

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On 6/1/2018 at 3:11 PM, Michael_Molnar said:

Sometimes I wonder whether "full spectrum" sunlight is superior to a UV cabinet. Of course, UV has the energy to effect changes, but the IR might help in another manner. Just thinking out loud. 

 

On 6/1/2018 at 5:42 PM, Jim Bress said:

Let’s see. This morning before work I planed and rounded the end grain of some belly and back cut-offs down to fresh wood for the viola I’m making for test varnishing. I put the two pieces in my light box to tan. Basically trying to do things as near to how I will varnish the instrument. 

Just now I planed another cut off of the same belly and back that I will exclusively tan with the sun.   We’ll compare in 10 - 14 days. The sun tanning will be unpredictable because of rain days and the annoying habit of the earths rotation. 

  1BAAAB56-70AD-4B2B-8F20-7AE315C00B2B.thumb.jpeg.9faa0fbe68ba0cc52531b04d317c27e6.jpeg

220 hrs. I UV (light box) vs. sun light (including overcast days) when it happened to be out.   Sun exposure definitely works faster because in spite of rainy days and night time hours the sun samples kept pace with the 24/7 light box.  My verdict with wood in hand, turning and tilting in the light trying to find something different about the two treatments is no visible difference between tanning wood with UV lights or sunlight. 

   22F0FCED-07F2-4A78-9523-BD83A2AF1814.thumb.jpeg.b2bd0a8980bea5acbf14ed0f20525f4a.jpegA1447A13-31B9-49DC-B22D-1C3A5B7F6A91.thumb.jpeg.52c9c183e4743d55072059548d23b79d.jpeg

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11 hours ago, Jim Bress said:

  My verdict with wood in hand, turning and tilting in the light trying to find something different about the two treatments is no visible difference between tanning wood with UV lights or sunlight.

Did the tanning penetrate to the same depth?

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On 6/2/2018 at 11:03 AM, joshuabeyer said:

http://www.solacure.com

These bulbs and ballasts have sped my tanning time from 4-6 weeks to 4-6 days.

You can find those cheaper: https://www.easy-lightbulbs.com/light-bulbs/uv-lamps/

They are used a lot. UVB is safe, UVC is much more efficient. Sunlight has a lot of UVC in its spectrum, but this light is eye damaging. The process was analysed in great detail: https://www.ncbi.nlm.nih.gov/pubmed/26974579, Full paper is available here https://www.researchgate.net/publication/297647292_Wood_degradation_under_UV_irradiation_A_lignin_characterization

It should also make the wood lighter, as mentioned by others, as fungal treatment does. You need a lot of UV light to seriously damage the wood though.

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On 6/2/2018 at 11:03 AM, joshuabeyer said:

http://www.solacure.com

These bulbs and ballasts have sped my tanning time from 4-6 weeks to 4-6 days.

You can find those cheaper: https://www.easy-lightbulbs.com/light-bulbs/uv-lamps/

They are used a lot. UVB is safe, UVC is much more efficient. Sunlight has a lot of UVC in its spectrum, but this light is eye damaging. The process was analysed in great detail: https://www.ncbi.nlm.nih.gov/pubmed/26974579, Full paper is available here https://www.researchgate.net/publication/297647292_Wood_degradation_under_UV_irradiation_A_lignin_characterization

It should also make the wood lighter, as mentioned by others, as fungal treatment does. You need a lot of UV light to seriously damage the wood though.

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On 6/2/2018 at 11:03 AM, joshuabeyer said:

http://www.solacure.com

These bulbs and ballasts have sped my tanning time from 4-6 weeks to 4-6 days.

You can find those cheaper: https://www.easy-lightbulbs.com/light-bulbs/uv-lamps/

They are used a lot. UVB is safe, UVC is much more efficient. Sunlight has a lot of UVC in its spectrum, but this light is eye damaging. The process was analysed in great detail: https://www.ncbi.nlm.nih.gov/pubmed/26974579, Full paper is available here https://www.researchgate.net/publication/297647292_Wood_degradation_under_UV_irradiation_A_lignin_characterization

It should also make the wood lighter, as mentioned by others, as fungal treatment does. You need a lot of UV light to seriously damage the wood though.

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On 6/2/2018 at 10:56 AM, Bill Yacey said:

And further to that, I believe it will darken the wood visually too. Years ago I baked some wood in the oven, and it tuned a nice deep yellowish brown after a few hours. I can only think this is due to the IR toasting the wood surface.

I can't imagine that these low-energy photons would do much by themselves, but the important thing is TEMPERATURE (and time), whether you heat the wood with IR or convection or conduction from a bending iron.  

UV tanning is something completely different.

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21 hours ago, Janito said:

Did the tanning penetrate to the same depth?

I made "V" cuts with a chisel with one side of the cut 90 degrees to the surface of the wood.  To the limits of my vision and a shop light the color appears to be on the surface of the maple and spruce of both treatments.  I'm sure there is some depth, but I don't believe it's enough to make any practical difference so I didn't break out my microscope.  What I gained from this is that I'm not going to undergo the bother and potential risk (heat, rain, gust of wind) of sunlight when I have a light box that can safely do the same job.

Cheers,

Jim

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4 hours ago, joshuabeyer said:

 

Sorry but I think you are mistaken. While they are indeed cheaper, the bulbs at your link are very basic UV lights, they have none of the upgraded qualities which expedite wood tanning.

I think I bought them there, mine are about 100W per tube. The parameters that count are power (in Watts) and the frequency (uva uvb uvc are frequency ranges). There are no slower photons, they all travel with speed of light. But you can have a higher flux density. I tanned wood with this already, got a nice yellow colour within maybe a week. The uvb dries varnish in a few hours.

The more expensive ones are 1000W. Higher power will certainly tan wood faster. How strong a lamp do you use?

But the result with a box with 2 x 100 or  150W was quite satisfactory.

Sorry for having posted it trice. This was an accident.

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