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Posted

Roger and Elliot,

 

I Was wondering about this myself -- if the resulting stuff from the slacking process is simply calcium sulphate, couldn't we simply start with this stuff described as Chalk of Bologna?

 

This stuff isn't all that expensive and a Kilo would probably last many of us a lifetime!

 

Chris 

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Posted

I enjoyed making mine and it wasn't difficult with a drill and a plastic paint stirrer.  There is something about making your own stuff, like mulling pigments to color varnish.  It just feels very cool to do it.

Posted

Roger and Elliot,

 

I Was wondering about this myself -- if the resulting stuff from the slacking process is simply calcium sulphate, couldn't we simply start with this stuff described as Chalk of Bologna?

 

This stuff isn't all that expensive and a Kilo would probably last many of us a lifetime!

 

Chris 

Chris, I'm just trying to add to your question.  

 

The Kremer site also lists "Selenite, Merienglas, fine" http://shop.kremerpigments.com/en/pigments/selenite--marienglas--fine-11810:.html 

 

"0 - 80 µ, gypseous spar, from Cyprus. Specific crystalline structure (plates) make this product especially suitable for violinmaking, where it is used as a clear filler in oil varnishes."  

 

But I seem to remember something about particle sizes should not be too small.  Although I have no idea how small too small is.

 

-Jim

Posted

 

I Was wondering about this myself -- if the resulting stuff from the slacking process is simply calcium sulphate, couldn't we simply start with this stuff described as Chalk of Bologna?

 

 

First of all, the Chalk of Bologna page doesn't state which form of calcium sulphate it is. There are three or four forms of it, and to the best of my knowledge, we want calcium sulphate dihydrate (aka gypsum). Second, if you look at the Material Safety Data Sheet for Chalk of Bologna, it says that it is a mixture of calcium sulphate and calcium carbonate. It might be interesting to experiment with, but it's not quite what Roger's recipe requires.

 

Chris, I'm just trying to add to your question.  

 

The Kremer site also lists "Selenite, Merienglas, fine" http://shop.kremerpigments.com/en/pigments/selenite--marienglas--fine-11810:.html

 

"0 - 80 µ, gypseous spar, from Cyprus. Specific crystalline structure (platefos) make this product especially suitable for violinmaking, where it is used as a clear filler in oil varnishes."  

 

But I seem to remember something about particle sizes should not be too small.  Although I have no idea how small too small is.

 

Selenite is a form of gypsum ( http://en.wikipedia.org/wiki/Selenite_(mineral) ), so this could be what you want more or less. I don't know if Roger's recipe depends on having any particular particle size or crystal type - he will have to speak to that. I do know that if you're looking for selenite powder in particular (and not just "gypsum powder"), eBay has it for US$9 per half-pound (about US$40/kg).

 

For those who want to try their farm or garden store, make sure the gypsum has no additives. There are quite a few "Gypsum plus Advanced Soil Technology"-like products out there, which are 98% gypsum with 2% other plant-encouraging additives.

 

Mr. Hargrave is right about slaking it yourself being more fun, and I am often in the company of those who just like to do it themselves, but it truly is a Rude Goldberg process to buy Plaster of Paris and then slake it so you can get gypsum out of it. Plaster of Paris is manufactured by heating gypsum to drive out the water molecules. Roger's process then puts the water molecules back in, resulting in... GYPSUM! :)

 

Hope this helps,

Elliot

Posted

Elliott, Thanks for the info on what is happening when when we mix the plaster of paris.  Its always helpful to understand what the process is doing when trying to arrive at an end product.

 

-Jim

Posted

Here we go again. Sorry that it has taken so long to reach this next stage. Just too many things to do all punctuate by musicians dropping off their instruments for the summer recess.

 

So the first job was completing the drying shed which I managed to do three weeks ago before I went to Greece and lost even more time being forced to enjoy life with my family. Actually they weren’t so bad. I finally got it together and wallpapered it with silver foil wallpaper. Unfortunately, the electric company sent the wrong lamps, but since I am running out of time and had already mounted the units and since Rene insisted that they will work anyway, I have inserted them into the units. There are two Phillips TLD 18watt BLB 60cm. and four 120cm BLB tubes. (not sure of wattage on these longer tubes). As I suggested I would have preferred to have UV lights that Phillips make for drying paint and eventually I will order these. I just hope that these BLB tubes will actually work. Does anyone know anything about them?

 

Actually my rabbit piss mixture slowly turned the wood brown over the intervening weeks and it has not been necessary to UV the bass. The color as you can hopefully see is quite nice. (I hate this bloody US spell check it drives me made to see colour spelt color.) So basically I just smeared on the mixture as I described it in the viola varnishing process. It’s just a whole lot more work, especially when rubbing it in and then off. It is really important to rub it in really well and then to rub it off really well. I use two brushes; a dry one and a wet one. The dry one is for getting the last bits out of corners and edges. However you need to be carfull not to roughen or scuff the surface when doing this. It is especially important to seal the end grain and belly edges. You need to have everything well planned before you start. The photos show the plaster mix being applied and then drying out after it has been rubbed in and off. I also did a violin this afternoon, it took me about 40 minutes. The bass took me about 4 to 5 hours. My new dog had to have a pee in the workshop, because I was too stressed to take her out. Another lesson learned. I don't know if dog piss works as well as rabbit piss, but somehow I don't think I will will be trying it out.

 

Unfortunately the belly/rib joint popped open in one place so I had to re-glue this. It did not take very long but it had to be done very carefully. I can’t remember if I said that I am extremely careful not to get any glue anywhere on the surface that is going to be varnished.  Actually I just found what I wrote.

 

“Having liberally glue sized the blocks and linings and also the belly edges the previous day, we simply clamped everything together. Then removing two or three clamps at a time, we slowly worked our way around the overhang with a hot slightly wet knife. It is important to keep two or three thin pallet knives in water that is around boiling point. They cool enough in the air before reaching the belly/rib joint. These hot (not too wet) knives soften the glue just enough to reactivate it. Again this process helps prevent excess glue from spreading. In spite of this Rene again placed masking tape around the ribs to stop even the smallest drops.”

 

Yes, I cannot emphasize enough the need to keep glue off the surface that is to be varnished. Any drop will leave a white fleck. We deliberately made the glue quite weak for the belly/rib joint. I also do this on violins to make any subsequent removal easier at some later date. Maybe I made it too weak or perhaps I got it too wet when applying the plaster mix. Either way the belly /rib joint opened. But, as you can see, I fixed it this afternoon. Tomorrow morning I will apply the first coat of varnish. (Fingers crossed!)  

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Posted

I am not sure how many photos can be downloaded at one time so here are the rest. They are the dry instrument followed by fixing the open rib/belly joint and repair. And finally, the various stages of the dog, gradually getting bored with the whole thing. Still she is only three months old. My family has been with it for between 28 and 45 years and they are still bored. I will show you the fiddle tomorrow if anyone is interested.  

 

 

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Posted

As I suggested I would have preferred to have UV lights that Phillips make for drying paint and eventually I will order these. I just hope that these BLB tubes will actually work. Does anyone know anything about them?

 

The BLB tubes have the dark filter that cuts out most of the visible part of the spectrum, but lets thru the UV that does the curing.  I have used both, depending on what I could get my hands on, and I couldn't notice any difference in drying.  I prefer the BL ones, so it's easier to tell when it's on.

 

(I can understand spellcheck letting you get away with "made" instead of "mad", but how did "spelt" get thru??)

Posted

I love how you store the nut... might get mixed up with violin parts if stored on a shelf? :)

E

 

It not the nut you nut its my emergency bar of chocolate.

As for the spell-check it never seems to work and I am a crap speller anyway.  

Posted

So here is the fiddle first. It took me about 25 minutes to put the first varnish coat on, rub it in with a cloth and then rub it all off. This is quite an intense process and it is absolutely critical to the finished appearance. After I have sealed the surface with the plaster mix I often use soft school chalk for the edges. I just run it once all around and then rub it in with my finger. Sometimes this is not necessary, but the edges are particularly prone to soaking up the varnish. If they are not sealed well enough they will go black. (Filler and varnish is probably what Strad used to fill his errant purfling stings.) You have to watch this though. Too much and the varnish won't penetrate the chalk and instead of the black, you will be rubbing like crazy to get rid of the white spots. 

 

Also, I always have a little of the dry plaster powder at my side. If the varnish is sinking in too much, you can rub it into the offending areas with a lint free cloth. You mix it with the surplus varnish before you wipe it off. It is essential to take every spot of varnish off the surface. Sorry to say that you can only really get the hang of this with a little experience. It is not difficult, but it is also fairly easy to mess up. The fiddle is a fantasy del Gesu copy circa 1742/44. 

 

The first two pictures are of the back and front sealed with the plaster mix. The others are the various stages of the first coats.

 

The bass took exactly five and a quarter hours. I had to take the dog out three times. The process was fairly simple. In some ways it was easier than the fiddle, but it was physically hard work. Just holding the thing and turning it over is difficult enough. My workshop is not tiny but it is not big either. The most exhausting part was rubbing the stuff in and off, while making sure that the edges were sealed and that any places that were soaking up the varnish were sealed with additional powder. It was really a case of a bit at a time. With this initial coat it is not a problem moving the instrument around once the coat has been rubbed in and off. There is no surplus on the surface. This means that you can go and have your lunch or take the dog out between areas. This will not be quite so easy when I come to do the final varnishing and I will need to think very carefully about this.

 

I started with the head and neck. Then I had a cup of tea before doing the ribs. As can be seen from the photo, there is quite a lot of varnish on the rib. I try and spread this as far as possible. If you are not careful this can be a very wasteful process. I have several small strips of perspex of different shapes and I use this to take off (scrape off) any surplus before I rub it in and wipe the surplus off.  

 

After the ribs I went onto the back. It really is essential with a bloody bass, (sorry) double bass, to make sure that you have enough varnish to finish the job. I guessed quite well, but I had some extra ready. The reason why this is so important is that I use dryers with this first coat. Just a normal artist dryer for adding to oil paints will do. I use half the recommended dose. However, I really do want it to dry thoroughly before I apply the final coat or coats. For the top coat or coats I do not use dryers.

 

Some of you may have noticed a few scratches. These were not deliberate, but as you can see from other areas I have partially worn the bass already. Because of this I have not been particularly careful on purpose. If you get my meaning.  

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Posted

Now, before I close to find out what is happening in the world, (no comments here. I remember the last time I made a remark), I want to say something about the use of glues. I am meticulous about not letting surplus glue onto the surface to be varnished. BUT as you can see from the following photo when we bent and glued the back, a tiny amount of glue squeezed through the joint, (close to the center joint). The resulting white spots (animal glue) can be clearly seen. Imagine this on a larger scale and you have some idea about what can happen. I have said all this several times on this blog so - no excuses.  

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Posted

wow these images are fantastic Roger. how did you achieve the variation in colour intensity on the belly of the fiddle? Did you rub the varnish/ground out more in some areas to achieve the light passages or leave more ground on the surface in the darker spots achive the effect?

Posted

wow these images are fantastic Roger. how did you achieve the variation in colour intensity on the belly of the fiddle? Did you rub the varnish/ground out more in some areas to achieve the light passages or leave more ground on the surface in the darker spots achive the effect?

 

I wanted the fiddle and the bass to look a bit authentic. a lot of those marks were caused by the scraper; in such areas the varnish penetrates more. The varnish is dark but not quite as dark as it appears in the pot. The ground color is the main source of the color. It always looks so intense because the plaster mix is so white. Now I really am off to bed.

Posted

Very interesting to follow. I have a friend making a bass at the moment. I must show him this thread. When I hold the top at his workshop I was wondering how it can hold without cracking in winter time. It is a big instrument!

 

Thin diluted top coats are not an option for you?

 

Good night

 

Peter

Posted

That glue spot,  it penetrated through the wood from the inside?   Interesting.

Well, after cutting the groove at this bend, the wood is only about 0,5 mm thick. Don't take too much to penetrate that. Its the reason we used thick glue for this job.

Posted

Roger:

 

This rabbit urine business.  I don't have a rabbit but am interested in experimenting with this #1 output on instruments.

 

Is something like this good would you think?

I think this might work, but it will require some preparation. If you give it a try let me know. At first I thought it was a spoof. I suppose its used for hunting. It would be better to take it off the market for this purpose.

Posted

Roger and Elliot,

 

I Was wondering about this myself -- if the resulting stuff from the slacking process is simply calcium sulphate, couldn't we simply start with this stuff described as Chalk of Bologna?

 

This stuff isn't all that expensive and a Kilo would probably last many of us a lifetime!

 

Chris

There are lots of things that work. Its all about giving it all a try. I would guess that it is OK.

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