Making a double bass

[Roger Hargrave]

Next week, I will be sending to Ariane my STRAD article "Optical Effects for Luthiers". There, I discuss RI matching that Roger mentions. The important take from my article is that the RI's need only be close to work as Roger finds.

Stay Tuned.

Mike

 

That's right! I look forward to reading it.

[Oded Kishony]

Have you ever noticed that different fiilers change the sound in unique ways?

[Roger Hargrave]

Oded Kishony, on 11 May 2013 - 8:34 PM, said:

Have you ever noticed that different fiilers change the sound in unique ways?

 

The short answer is no! I imagine that some fillers are better than others, but here we get into that old chestnut; what influences sound. I'm afraid there are just too many factors that need to be taken into consideration.

 

Of course the use of fillers almost certainly does do something that fundamentally influences sound. Most importantly it seals the pores of the wood and stops deep penetration of the varnish, whatever that varnish might be. I certainly believe, but have no proof, that once I started using fillers, almost a lifetime ago, my instruments gained in both the quality and production of sound.

 

Over the years I have I tried several tests with instruments that I made before and after I started using fillers. Those on which fillers were used certainly carried better in large halls. However, although they remain intrinsically similar, I change my fillers as often as I change my socks and my varnish almost as often as my underwear. As I indicated earlier on a regular basis, I also change my method of application. So working out which fillers best influence the sound is a none-starter for me. As you will have noticed from other posts I am extremely skeptical of people that claim to be able to identify instruments by their sound, and here we are talking about picking out minor changes as a result of applying similar fillers. So the long answer also turns out to be no!  

 

I might add that some thirty five years ago I made a copy of a Testore violin that completely fooled two top connoisseurs. (Both now sadly deceased.) I was over the moon - until I went to a concert being given by the man that owned the original. After the concert he played my violin which sounded very nice even against the original. I then asked him to play again while I went to the far end of the hall. I was seriously shocked to hear the difference in carrying power between the two. I was then seriously depressed for many weeks. I kept thinking about how useless it was to make a violin that could fool an expert visually, while in terms of sound production it did not even come close.

 

This was about the time that John Dilworth and I started looking at the possibility of analyzing varnish samples. This led to the works of Professor White, and Barlow and Woodhouse. I can clearly remember the influence that those first electron microscope pictures had upon my thinking. From that moment I began reading about fillers and extenders and experimenting with their affect on both the sound and appearance of my fiddles.

 

Since those heady days I have been happy to put my violins up against any classical instrument. Don’t get this wrong. I am not saying that my work is as good as those classical Cremonese makers. If I had the money I would buy a great Cremonese violin immediately, but sound-wise I am no longer afraid. And although there are many factors that make a great violin; just as no one single part that makes a great automobile, for me the biggest single step forwards that I have made, has been introducing the concept of filler/extenders to my varnishing process.

 

Back in those days we had to get these things off the ground ourselves, with the help of family, friends and connections. Today it is all out there on a cloud somewhere, waiting to be harvested like manna from heaven  

 

Actually I do not see it as my remit to explain everything, even if I could. I will explain what I do and a little of why, but those that want to know more will have to look for their own answers. Which neatly leads me to coloring the wood before the filler is applied. 

[Melvin Goldsmith]

Hi Roger,

I use a similar mineral filler type ground to what you describe. I share the feelings you describe above. Also I would not feel confident of getting the look I wanted without it. Thus I was quite surprised when the recent published research from Echard and from Brandmair seems to find no evidence for a mineral ground.  I wondered if you had any feelings on this? ...the varnish research is ongoing I guess...( maybe it's a topic for a different thread rather than diluting the theme of this one)

[Guest]

This is really getting good...

[Roger Hargrave]

Hi Roger,

I use a similar mineral filler type ground to what you describe. I share the feelings you describe above. Also I would not feel confident of getting the look I wanted without it. Thus I was quite surprised when the recent published research from Echard and from Brandmair seems to find no evidence for a mineral ground.  I wondered if you had any feelings on this? ...the varnish research is ongoing I guess...( maybe it's a topic for a different thread rather than diluting the theme of this one)

 

 

Yes, well it depends on who you consult and how you interpret that information. I know Brandmair's work very well and it is exceptionally valuable. (See my post recommending her book) However, as a working violin maker I am not simply trying to reproduce that which the great Cremonese makers produced. In the first instance I am trying (as I always have) to produce a fine looking varnish that enhances the instruments tone rather than diminishing it. As a copyist I also want a varnish that is flexible enough to use for different models. All of this is difficult enough. 

 

Getting to the roots of the great (truly great) Cremonese varnishes is a slightly different story. It is what inspires and motivates us, but if we are smart our first priority is to find something that works well both tonally and visually. I am making a bass with René Zaal and I want it to look stunning and sound like a train full of petrol and TNT, hitting a fireworks factory at full speed. And if you are not carful with some of the alternative coloring methods that might be exactly what happens to your instruments.

 

Unfortunately for those of you that want to know more, as far as the initial coloring process is concerned this is not going to be easy. The reason for this is that, on this bass, I have used Koen Padding’s ‘Primer I’ and ‘Primer II’ in a fifty-fifty mix. Even more unfortunate (for me) is the fact that I have completely used up all of my reserves of this primer. The bass simply soaked it up, to the extent that I just managed to cover the instrument before I ran out of the mix. I have been using this fifty-fifty mix for many years. I initially worked with Koen on this idea, but when he began making it professionally I stopped. The main reason why I stopped was that it is a messy job and it was always, at least for me, very hit and miss. Koen’s mixes had a shelf life, but at least they were reliable, and for me they were free.

 

I am in the process of making something similar for myself. This involves working with animal urines and feces (rabbit and horse). The resulting substance gives the wood some color, but most importantly it reacts with ultra violet light to create a warm golden brown hue, which accentuates the darker reed lines of the spruce. Because this was a major source of income for Koen’s family, I always promised not to say how it was made. (Although I only know the basics of the method) So far no recipe has been forthcoming amongst Koen’s effects. However, if it does turn up the family may wish to continue marketing the product. Until such time I am still bound by my word. I hope that you all understand this. If anyone has any alternative suggestions then please feel free, but please don’t expect me to comment right now.

 

If you are prepared to wait, the easiest way is to use ultra violet light. If not then you might wish to try one of the following.   

 

In the past I have used potassium nitrite (KNO²) to good effect. However, potassium nitrite is toxic if swallowed. It is also a strong oxidizer and it can accelerate the combustion of some materials. It is important to use gloves and safety glasses when handling potassium nitrite.  When reacting with acids, it forms toxic nitrous oxides. Fusion with ammonium salts results in effervescence and ignition. Reactions with reducing agents can result in fires and explosions. So before you use it make sure that you know what you are doing.  

 

Another alternative is ozone. I used ozone for several years, but it is also toxic in enclosed spaces. I am not sure of the long term effects of ozone on the wood. I don’t really want to recommend it.

 

As for the rest of the varnishing process I have always used my own recipes and methods of application which means that I can describe them here.  

 

For the moment the bass has been covered with Koen’s primer I&II mixed together. In order to stop the mix penetrating the belly in an uneven manner, I pre-wet the belly liberally beforehand with lukewarm water. Although it is important for the belly to remain wet during the application, it is essential to dry off any surface water with paper towels or a cloth, before the mix is applied. It is not necessary to pre-wet the head back and ribs.  Once everything is completely dry, the bass will be placed in UV light until it is nice and brown. I still need to build the UV box, but I could not wait to apply the first color to the wood. 

[Guest]

One thing I really regret is not having tried any of Koen's primers. I loved his sandarac varnishes. I hope that his family can and will continue to make the primer available.

[actonern]

"...This involves working with animal urines and feces..."

I always thought your instruments look like shit!

 

Seriously, this is just an outstanding thread!!!

 

E

[Roger Hargrave]

Let me return to sunlight or UV. Exposure to UV is almost unavoidable if you are intent on drying any linseed oil based varnishes. It may also have been the way in which they colored (browned) and to some extent even seasoned their instruments. We should not forget that according to dendrochronologists, they often used quite fresh wood. The Hill book mentions that Strad had some kind of open roof area. This would have been ideal for catching some rays. But I live near several horses and I have experienced the effect of flies. They don't just die; they drag their poor little wings along, leaving trails that a blind dog with no sense of smell could follow. Cremona had and still does have mosquitoes like helicopters. Moreover, at that time the presence of horses and other animals along with a general lack of hygiene must have spawned millions of varnish ruining insects. So if, (and I assume that he did), Strad was using the sun to dry his varnishes, then even in those days he must have used some form of fly screens. Since Cremona was a highly important center for silk weaving I see no reason why this could not have been the case. Over the years, all the best coloring agents that I have used are basically oxidizing the wood. Sunlight does exactly that and in my opinion it is one of the best. For people like me that live in the world’s largest grey zone a UV cabinet is a necessity. However, if extreme caution is used you can employ stronger lights that will work a little quicker. (UVB) They are used for sterilizing in hospitals, BUT they are very dangerous and they need to be used with caution. In some countries they are only sold under license.   

[actonern]

Roger:

 

Exposure to sun or UV bulbs seems to have the effect that a month of exposure is required to effectively "double" the effect of the first week's exposure.  How long do you typically hang your instruments?

Best regards,

 

E

 

[Michael_Molnar]

"A fly in the ointment" now has a new meaning for me.

 

FWIW: As for UV lamps, I suggest staying with the safe black light lamps (UVA). I experimented with UVA, UVB and UVC. The total lamp wattage is key. That is, increase the UV brightness by adding more lamps. Make sure the cabinet does not get too hot. A ventilation fan is helpful.

 

Mike

[Conor Russell]

Something I should remember, but which are the sunbed tubes, and how dangerous are they with very short exposure?

I know you mentioned the dangers at your talk at the VSA Mike, and I think people should be aware of them, and take them seriously.

[Jim Bress]

Something I should remember, but which are the sunbed tubes, and how dangerous are they with very short exposure?

I know you mentioned the dangers at your talk at the VSA Mike, and I think people should be aware of them, and take them seriously.

So much important information gets posted here that I could not possibly remember it all unless I save things in an orginized fashion.  In my wood tanning file I have a post by Jeffery from Koen Padding that I hope is appropriate to repost here.  Unfortunately I did not save the thread link, Maybe I should from now on.

 

Jeffrey Holmes wrote:

I received the following e-mail message from Koen Padding and am posting it on his behalf:

Hello Jeffrey

While browsing the maestronet I saw some entries on drying cabinets. Because all types of lights (UVA,UVB and UVC) are potentially dangerous and the entries seem very confused about the subject I thought I should respond but am not a member so my response is to you. UVA, B, and C are of decreasing wave length and increasing hazard in this order. UVA is similar to natural sunlight and all that is needed to dry oil varnishes, but it is already not wise to look straight at it with unprotected eyes. UVB often referred to as "blacklight" is definately ruinous to your eyesight and can e.g. be used for sterilization of hospital rooms. That’s how highly energetic these short wavelengths are. This is important because one of your entrants actually advises to use it probably because he cannot see any light when looking at it and does not realize that a blacklight is even more UltraViolet than UVA. A drying cabinet is best and safest made with about 250 Watts/m3 of ordinary Suntanning Tubelights. E.g. Phillips UVA  colour Nr. 3A The 120cm long tubes are 80 Watts so 4 of them in a cheap double doored wardrobe 180 X 60 X 120 cm will make a good Cello sized cabinet. Replace the top by mosquito wire against overheating and bugs. Line the inside with Aluminum foil Don't run the cabinet in your workshop or house, All UV lights produce Ozone and through that some Nitrous monoxide (UVB and C even more so) but have it in the garage or a well ventilated room.  Don't use blacklights because:

-They are too intense and dry the varnish too fast.

- The gasses they produce are bad for varnish and although   the Nitrous monoxide will colour wood nicely, in the long   run it is destructive to it. This is because it promotes the formation of "free radicals" in the wood which spead up its ageing process in an uncontrollable way.  If you ask for UVC at your local shop you'll probably end up on the FBI potential terrorists list.

 

Sorry for the length of my reply

regards

Koen Padding

[Michael_Molnar]

I don't want to hijack this great thread, but the above posts need emphasis.

 

Never use UVB and especially UVC. These lamps emit powerful UV rays that do not speed up drying. They just emit the extremely harmful UV that causes cancer and eye cataracts.

 

UVA lamps look black. My experience with UV lamps is that UVB lamps are white; UVC are clear. Check the labeling on your UV bulbs.

 

Sorry Roger.

 

Mike

[JohnCockburn]

Not true that all UV lamps produce ozone. Short wavelength UVC is required.

 

As Mike correctly says, blacklight tubes are UVA, not UVB as stated in #213.

But there are white UVA tubes as well as black*. The black ones are just designed to filter out visible light for use in various dark dens of iniquity frequented by the younger generation.

 

* specifically, actinic fly killer tubes.

[Roger Hargrave]

"A fly in the ointment" now has a new meaning for me.

 

FWIW: As for UV lamps, I suggest staying with the safe black light lamps (UVA). I experimented with UVA, UVB and UVC. The total lamp wattage is key. That is, increase the UV brightness by adding more lamps. Make sure the cabinet does not get too hot. A ventilation fan is helpful.

 

Mike

 

 

Actually I no longer use UVB because they are too difficult to get here in Germany. I have never used UBC. I had thought that UVB were quicker, but you are probably right about increasing the wattage being better and it is undoubtedly safer. I added lights about two years ago and it was extremely helpful. Actonern suggests that longer exposure gradually works more slowly. I would agree, I usually only sun for about 10 days and nights continually. After that not much more happens. In fact I think that seriously prolonged exposure might even be detrimental, but that's just a guess. 

 

Yes and sometimes I just write without thinking so you are all correct in putting me right on this one. Actually I have no excuses, because I already know all of that stuff in Koens notes that Jim so kindly posted. It just went out of my head, but I have also copied it again. I only ever used UVB for browning, but as Michael suggested it probably doesn't work any faster.

 

My varnish is touch dry in about 6 to 8 hours with UVA (normal sun lamps).   

[JohnCockburn]

Power requirements for tanning and varnish drying are very different, I think. 

Very little power seems to be needed to dry varnish. I noticed this recently when 2 of my 4 tubes died and it made no difference to drying time whatsoever. I remember someone else (Conor maybe?) has previously posted similar observations.

[~ Ben Conover]

If you hang the fiddle infront of the tubes, then the top of the scroll and the end pin areas will receive very little exposure.
 

[Roger Hargrave]

If you hang the fiddle infront of the tubes, then the top of the scroll and the end pin areas will receive very little exposure.

 

 

 

Agreed; I have lamps above and below the instrument. I also covered the inside of my box with aluminum foil before mounting the lamps. I am not sure if this does anything, but it looks nice. What it may do is increase the heat that is generated. Either way air circulation is important; however it is not advisable to use an electric fan because fumes from the varnish might cause an explosion. Two large holes on opposite sides, one up and one down should be enough to create circulation. 

[Don Noon]

Agreed; I have lamps above and below the instrument. I also covered the inside of my box with aluminum foil before mounting the lamps. I am not sure if this does anything, but it looks nice. What it may do is increase the heat that is generated. Either way air circulation is important; however it is not advisable to use an electric fan because fumes from the varnish might cause an explosion. Two large holes on opposite sides, one up and one down should be enough to create circulation. 

I researched what to use on the walls of my lightbox to get the most UV reflection, and aluminum foil is quite good.

 

Varnish fumes would need a spark or hotspot for ignition; I believe almost all small ventilating box fans are brushless... no sparks, and should be safe.  I'd be more worried about any switches on the lightbox that turn the power on or off.

[Adam Edwards]

My lightbox consists of 8 x UVA blacklight tubes , exhaust fan ,  cooling fans for summer ( push air past uv tubes )  , and a thermostat to shut down lights if it gets above say 27c , then in winter I have a incandescent UVglobe 100watt or 60watt to boost temp inside box ,  25c is my preffered temp inside .

DO NOT EXPOSE MADDER COATS TO UV , my red coat dries outside the box .

hope this is of some use :-)

 

P.s. If anyone would like photos PM and I'll email photos from my iphone

[Oded Kishony]

If you are concerned that your madder will fade or change from UV exposure you should initiate the change in the UV box rather than waiting for it to happen when it is sold and an angry customer comes calling. ;-)

 

JMO

Oded

[Adam Edwards]

there is a top coat that softens UV exposure , what I'm avoiding is a super intense blast of UV , and the effects are only subtle ,  I sort of threw that one in  for you to mull over :-) 

[Torbjörn Zethelius]

If you hang the fiddle infront of the tubes, then the top of the scroll and the end pin areas will receive very little exposure.

 

I would think that all light inside the box is UV, even reflected light, so I don't believe it's a problem.

[Guest]

The suspense is killing me...