Making a double bass

[WalterOB]

Do you have any experience with using fresh urine? I don't have 18 month old rabbit urine accessible, but I do have a beagle that pees a gallon a day. If you have tried it, how long does it take for the smell to go away, and would you wait for the smell to go before you varnish?

I wonder also if the bacteria that is attracted to urine would feed on the hide glue and filler that is subsequently applied...

[Roger Hargrave]

I have a serious question. Would any urine do the trick why specifically horse or rabbit ? Is it the grassy diet ? Why the straw and dung then ? Is the secret in the straw ? Boiled straw tea solution ?

 

r.

 

No, as I understood it, the straw was to keep the dung from comming into direct contact with the wood. As for the urine I cannot give you an answer because I simply do not know. 

[Roger Hargrave]

Roger just want to point out that Nitric acid has been around than a millenium and started being  produced  more commercially in the 17th century using the Glauber process which is basically the process used today. So its not totally unconceivable it may have been used for some processes in the art material world.

 

Point taken, I was thinking in terms of commercial production. Historically urine was an important source of one of the crucial ingredients in gunpowder; saltpeter, also known as niter. In order to extract saltpeter from urine historically, gunpowder manufacturers set up “niter beds” of straw, filtering the urine through the straw, which would concentrate the salts for easy collection. Maybe that is what Aubert were up to with their layers of straw.

 

Actually you cannot simply make gunpowder from urine. You need several other ingredients to produce it. If you really want to know more consult the net. Actually the nature of your question suggests that you already know way more than I do. But for others, until World War I, before people learned to produce niter synthetically, urine, guano, and manure were all collected to produce gunpowder. In most communities outhouses were fitted with trays under the toilet seats that could be pulled out. These were emptied by night-soil men who came with wagon to collect the contents. This was then dumped into tanks where it was allowed to ferment. Then the liquid was run through ashes into shallow evaporating trays to recover the saltpeter.

 

Initially, saltpeter was scraped from the walls of stables; there is your horse piss again, but this was inefficient, so people started collecting urine and dung. Koen did a lot of research on this subject, but as I told you earlier I cannot tell you exactly what he was doing. And for the moment I would not do this even if I knew it exactly. Koen discovered that amongst other authorities the French army stringently controlled the collection of night-soil. Why might that be important? 

[Roger Hargrave]

Do you have any experience with using fresh urine? I don't have 18 month old rabbit urine accessible, but I do have a beagle that pees a gallon a day. If you have tried it, how long does it take for the smell to go away, and would you wait for the smell to go before you varnish?

I wonder also if the bacteria that is attracted to urine would feed on the hide glue and filler that is subsequently applied...

 

 

I would not use fresh stuff the smell would be too intense. I think it needs to ferment. As for the bacteria attacking the glue I doubt that it would do much once it had dried out. Bacteria need moisture. There is a fine example of tons and tons of dung being found in a cave in a desert in North America. It is mainly from a species of giant sloth, now extinct. It is many thousands of years old; from long before the last big ice age. It has not deteriorated because there is no moisture in the cave. It has simply mummified. It even still smells. That is all I am prepared to say on this subject.

[Violadamore]

I have a serious question. Would any urine do the trick why specifically horse or rabbit ? Is it the grassy diet ? Why the straw and dung then ? Is the secret in the straw ? Boiled straw tea solution ?

 

r.

If an ancient process calls for a specific urine, i wouldn't stray from it.  All pee is not created equal.  E.G.:One of Paracelsus's recipes calls for "urine of a winedrinker".  You get into a lot of things besides just urea, like ketones and stuff

[Roger Hargrave]

Regarding rabbit piss, i treated wood years ago with it due to having a readily available source at the end of the garden. It has interesting properties ,eventually producing  a hard mineral ground on the wood surface after repeated soaking of the surface and drying/uv ,it becomes transparent under oil varnish.

 

There you go!

[Roger Hargrave]

Just reading through this again I don't want to be responsible for a new generation of fiddles that stink of piss. Although on second thoughts I supose it might be preferable to them looking like shit. 

[bmccarthy]

Or worse......both :-)

[Berl Mendenhall]

I have this vision of someone holding a rabbit up while someone else holds a jar under it waiting for the rabbit to pee.  I think I'll just stick with Roger's plaster of Paris.

[pbelin]

Could one not use the rabbit to stir the plaster?

[Berl Mendenhall]

Could one not use the rabbit to stir the plaster?

I like it.

[Roger Hargrave]

Could one not use the rabbit to stir the plaster?

 

Actually I have had good results just putting a live rabbit in the bucket with a lid on it. By the time it is dead the plaster is usually cured. However the amount that I will need for the bass will probably require an empty tanker and a horse. 

[Roger Hargrave]

Here are a couple of photographs of the final single varnish coat on the viola. It is just painted onto the ground, which as can be seen (post # 197) is just a single varnish coat rubbed in and off the filler/extender ground. I always add a little dryer to this coat, so that I am sure that it is well cured before I paint on the final top coat. I don't add drier to the top coat. This is a copy so I will wear the varnish. (Already done) However, for those of you that like to know these things, I always varnish my copies completely before I begin wearing the varnish off. I let this final coat dry for about 5 to 6 hours so that it is not too hard. If it is still a little soft it is easier to remove and scratch the varnish. From the photo the brush looks like a sable, but it is a high quality synthetic hogs hair artists brush. I use it for my painting work as well. Although thick, the varnish flows well enough for the brush makes to disappear. 

[JohnCockburn]

Hi Roger, do you "burnish" the plaster layer in any way before you put on the first varnish layer? Also is there any reason for using such a small brush for varnishing?

cheers

John

[Roger Hargrave]

Hi Roger, do you "burnish" the plaster layer in any way before you put on the first varnish layer? Also is there any reason for using such a small brush for varnishing?

cheers

John

 

No burnishing, I like the raw matt appearance of the ground. I know that Koen was keen on burnishing, but I never saw any advantage. Perhaps if you want a super clean finish, but that is not really what I am looking for.

 

The small brush just makes it easier when I get to the head. It saves having to clean two brushes, which helps to save varnish as well. Since the varnish spreads easily it does not matter. For cellos I do use a bigger brush.

 

Perhaps I should point out that the ground is dark not simply because I colored and sunned the wood. It is dark because I used the same dark varnish for the ground as I used for the final top coat. You can see this in the photo of varnish been applied to the head post # 197.    

[pbelin]

I've had ba experience with burnishing. I never actually used plaster, but similar products, and in parts where it was very nicely burnished the varnish didn't penetrate the surface anymore and the result was an opaque spot.

The sort of thing that doesn't happen in a quick trial piece but only on your nicest instrument, the one you pay really a lot of attention to!

But that only happened if one applies the powder with a solvent (water, alcohol, petroleum,...whatever one prefers), applying the powder with varnish doesn't cause that problem. (Providing there's enough varnish, beware of solvents!)

[Roger Hargrave]

I've had ba experience with burnishing. I never actually used plaster, but similar products, and in parts where it was very nicely burnished the varnish didn't penetrate the surface anymore and the result was an opaque spot.

The sort of thing that doesn't happen in a quick trial piece but only on your nicest instrument, the one you pay really a lot of attention to!

But that only happened if one applies the powder with a solvent (water, alcohol, petroleum,...whatever one prefers), applying the powder with varnish doesn't cause that problem. (Providing there's enough varnish, beware of solvents!)

 

I agree! I also think that the varnish keys better to an unburnished ground.

[Christopher Jacoby]

Violadamore-- that might be why the French hoarded their night-soil so. Lots and lots of wine...

[Johnmasters]

Discussion of filler-sealers involving plaster and silicates.

See next one.

[Johnmasters]

This seemed out of place as mentioned below.

 

[Guest]

.

[actonern]

"...Perhaps I should point out that the ground is dark not simply because I colored and sunned the wood..."

 

Roger; It's such a treat reading this thread...

 

Your quote above can be read to mean that you colored the wood by sunning it, or that you sunned it AND colored it.

 

If the latter, would you be inclined to share the process?

Best regards,

E

[NewNewbie]

"...Perhaps I should point out that the ground is dark not simply because I colored and sunned the wood..."

 

Roger; It's such a treat reading this thread...

 

Your quote above can be read to mean that you colored the wood by sunning it, or that you sunned it AND colored it.

 

If the latter, would you be inclined to share the process?

Best regards,

E

The method of applying the ground coat with varnish mixed in it as a binder, uses  colored varnish, so more than one source of color.

[NewNewbie]

I use a plaster of paris sealer-filler.  A very easy method is to mix the water 50-50 with alcohol.  It will sit in a cup indefinitely without hardening.

 

 

So you do not need to stir yours at all???

[Roger Hargrave]

Just to answer a few questions about varnish making. Germans are very fond of asparagus, a vegetable I consider highly overrated. Fortunately my wife Claudia loves them, which means that we have a stainless steel asparagus pan it is about 18 inches high and 6 inches in diameter. It is perfect for cooking resins. As I have already stated I cook outdoors well away from anything inflammable. I have a small temporary shelter to keep the cooker out of the rain. (I bought that book, ‘Fifty Shades of Grey’, because I thought it was about the weather here in north Germany. The shelter is well ventilated and allows me access to stir the resins. I keep a fire extinguisher close, but not too close. However an extinguisher will not stop either an exothermic reaction or an explosion. Initially to save time I cooked large quantities. This turned out to be a mistake. Without the appropriate equipment large quantities are difficult to regulate. The main problem is keeping an even temperature throughout. It is very easy to burn the bottom of the batch, while the top is being cooled by the surrounding air. Because even a small amount of burning will spoil the entire batch, it is best to cook smaller amounts. The resulting red resins can always be mixed together later and any burned batches can be discarded. As I pointed out earlier, whatever the resin a considerable amount will evaporate. Because the amount is often quite drastically reduced, instead of simply adding this red resin to the oil, I add it to oil that has already been blended with some colophony in the simple way that I described earlier. I cannot tell you how much; because this will depend upon how much of the red resin has boiled away. In the final analysis I just try to keep to the ratios that I mentioned earlier. I have never found this job easy. Moreover, I have shown many people how I make my varnishes, but in the end they all eventually find their own way. If you live in a desert or close to the Arctic Circle your requirements will be very different. I have cooked in frosty conditions and in summer temperatures of 30+ c. In cold conditions my electric bill was always huge. Never cook on an open flame. There are several historical reports of people being killed while cooking varnishes. In most towns and cities cooking varnishes was only allowed outside the city walls. I know personally several people that have received severe burns. Best of all is gaining access to a lab, where extractors and proper temperature controls are possible. Good luck!