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AMORI

Tripoli + resin sealer/filler

45 posts in this topic

In an article by Gregg Alf in the November Strad, he mentions using a paste of resin & tripoli as a sealer/filler. As you know, I am one to experiment and this is one varnish method I'd like to test for myself.

In this post I am hoping to establish exactly which resin one could use as a medium to combine with tripoli? Would anyone know?

Also, I'm told that tripoli and rottenstone are the same thing, can anyone verify that? I'm dubious about that as I have some rottenstone and it's grey rather than the red colour of Mr. Alfs paste.

Although this post is about trying to establish a resin-type for this experiment, I'd like to hear from members who have tried this "Alf technique". As far as I can gather it is not the same as the glazing we have previously spoken about where we combine artist colours with varnish - or is it?

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Amori, i would not use the grey rottenstone,it can get real dirty and embed in the pores .Fine pumice will do the same job as it breaks up the more you rub it in.

You can use mastic or even rosin, dissolved in terpentine as little as possible and as little oil as possible aslo.Your basically making a colourless thick varnish ,high in resins and low in oil but with not much solvent so that it doesnt soak into the wood too much. A few people on this board use a similar sealing process.

Pumice and Tripoli/rottenstone are usually varieties of soft Volcanic glass,it varies alot in colour depending on the region it comes from,for example fine Italian pumice called Pozzolan is usually white.

Ive had pinkish, yellowish, brownish and several other coloured types. Rottenstone is supposed to be the same as Fullers earth but whether it is or not im not sure,it certainly looks the same dirty grey colour.

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Hi Amori,

It's not same as the glazing technique as far as I'm

concerned. I use the  basically same technique with my normal

rather thick oil varnish (which has no solvent, anyway) and pumice

or Marienglas. My varnish is a simple mixture of linseed oil and

mastic, but my guess is that any resin should work just as

well.

Every time I get tripoli, it's pink, and when I get rottenstone,

it's grey. So, I'm almost sure they are different stuff even though

they're used for the same purpose, unless I'm missing something.

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I agree with fiddlecollector.

First, Rottenstone and tripoli are not the same thing. Tripoli is reddish pink and rottenstone is greyish in powder form, to blackish when wet. Tripoli is usually slightly finer than rottenstone, I think, but I'm not sure that you can assume much about any of these abrasives because they are all made from different minerals (if I'm not mistaken) and their grit is probably somewhat dependent on the way the product was processed. I have a couple of different rottenstones from different sources, and they are slightly different in color and grit - and my tripoli is finer than both of them, if only slightly.

I also agree with the idea of using pumice with resin as a ground or filler, because it becomes clear and cement-like when dissolved in the finish. I start with the finest obtainable for use in a finish, I use it in shellac as a ground coat, where it does not fully dissolve - I imagine that it could be used with resins such as Propolis, Gamboge or Dragons Blood, etc., where a specific property and/or color was desired also.

You're on your own as far as this type of thing goes, but I wouldn't hesitate to experiment whih these things because this is the type of simple thing that most people end up having as a proprietary sort of process. Many makers keep what works as a ground fairly close to the vest, I imagine, because it has such a great influence on the final look and perhaps even the tone of the violin...

Still, I think that the principals of these things are not that esoteric that the basic ingredients for something as workable as the $10,000 "secret methods" cannot be ferreted out fairly easily with some reading and experimentation (guffaw - sorry, I know that my irreverence is showing, my apologies)

Of course shellac IS considered a resin as are the different lacs (seedlac, sticklac ...) and should not be ruled out when considering ground materials just because they are commonly used on other things such as furniture, especially if color and durability are desired as a part of the ground/sealer.

I am no expert on this subject, which is as filled with different opinions and methods as plate tuning is.

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In the US Tripoli,is available in two colours known as cream and rose.The cream variety is softer than the rose. Apparently its in the UK ,Australia and probably South Africa that Tripoli and Rottenstone are seen as the same thing. Obviously the usual case of different countries /different naming ,like Parafin and Kerosene.

Also Tripoli according to google is a powder mined from old limestone beds. With three different types mined regularly in the US alone.

Im confusing myself.

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"As far as I can gather it is not the same as the glazing we have previously spoken about where we combine artist colours with varnish - or is it?"

"Glazing" and combining artist's colors with varnish in order to tint or offset its natural color, are two different things.

Glazing, as the term is usually used with regard to violin varnish, has to do with laying down a seperate layer of artists oil color between layers of oil varnish, wich may or may not have been pre tinted with artist oil colors or other colorants.

Correct me if I'm wrong - our own problems as violin makers may also have to do with using loose definitions, where one word ("glazing", for example) can refer to one of several different processes.

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CT you are quite right. The painter's method of 'glazing' is more similar to normal colored violin varnish than to what violinmakers refer to as 'glazing'.

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Does Alf refer to this as glazing? I'd say it's not glazing really. I agree to what is already said below; glazing has a precise meaning in painting at least: to apply a layer of transparent colour.

I've bought tripoli that is reddish and I've bought tripoli as white as snow; both work well, (however but I really prefer the white one for grounds). I think the terminology is really loose indeed.

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Greg Alf calls it a "sealer", not a "glaze". He does mention the reddish tone as beneficial to coloring.

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I am certainly no expert, and I didn't read the Alf article, but

this is my understanding regarding pumice, tripoli and

rottenstone.

Tripoli and rottenstone are two terms for the same thing, although

there are differences between the two when they are purchased. They

are a type of diatomaceous earth, which is finely crushed (via

geological pressure) marine shells, mined from geological

substrate. When viewed under a microscope, it resembles crushed

glass. It's typically used as a filtering compound, in pool filters

for example, as well as acting as a mechanical insecticide, in

addition to its traditional use as a polishing compound. According

to Kremer's catalog, Tripoli Light and Tripoli Reddish is very fine

pink rottenstone, which is made up of crystalline silica. Kremer's

Attapulgite, or Fuller's Earth, is grey rottenstone, and contains

magnesium-aluminum, as well as hydro-silicate.

Pumice is also a silicate, but it is derived from volcanic sources

rather than sedimentary sources. Obviously it has similar

attributes to Tripoli, with certain differences.

One last thing - Craig, if you're using Pumice mixed with Shellac

as a ground, wouldn't that make up essentially a French Polish,

which you then cover with your oil varnish? It sounds like a good

procedure to me, in spite of the fact that the French Polishing

literature I've read states that filling pores with pumice/shellac

is necessary for rosewood and mahogany, but maple and spruce have

small pores that don't require filling. I might assume that the use

of Pumice in your ground has a different function than the French

Polish pore filling.

This is a fascinating topic, thanks everyone.

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Here is more information on Diatomaceous Earth that I got from this

website:

"http://www.hydromall.com/happy_grower16.html">hydromall.com

Diatomaceous Earth is a natural occurring siliceous sedimentary

mineral compound from microscopic skeletal remains of unicellular

algae-like plants called diatoms. These plants have been part of

the earth's ecology since prehistoric times. Diatoms are basic to

the oceanic cycle, and the food for minute animal life which in

turn becomes the food for higher forms of marine life. As living

plants, diatoms weave microscopic shells from the silica they

extract from the water, then as they die, deposits are formed and

then fossilized in what are now dried lake and ocean beds. The

material is then mined, ground and screened to various grades, for

the countless uses in today's products and processes, from

toothpaste to cigars, plastics to paprika, filter media in swimming

pools to home fish tanks, as well as insect and parasite control in

animals and grains.Diatomaceous Earth is a natural (not calcined or

flux calcined) compound with many elements which include:Silicon

Dioxide SiO2 83.7%Aluminum Oxide A1203 5.6%Iron Oxide Fe203

2.3%Calcium Oxide CaO 0.4%Magnesium Oxide MgO 0.3%Other Oxides

1.9%Ignition Loss at 1000 5.3%Semi quantitive spectrographic

analysis of other elements:Copper 2ppmStrontium 100ppmTitanium

1800ppmManganese 200ppmSodium 2000ppmVanadium 500ppmBoron

50ppmZirconium 200ppm

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I use the french polish shellac method with pumice 4F all the time. I use it to fill in pores of rosewood or repair the surface damage of a previously french polished finish. There are two tricks: (1) use a minimum of shellac (mostly alcohol on the pad), and (2) pick the pumice up (I put it on a sheet of paper) with a wet pad so that the pumice is wet by the alcohol.

Why did I go into this amount of detail with a french polish finish? Well, You shold be able to use the same process with an oil-based violin varnish. I would use a very thinned down varnish, perhaps with lots of turpentine, and use the wetted pad to pick up the pumice or whatever. It is vital that the abrasive be wet by the varnish or you will see the original grey color of the abrasive. If wetted, the abrasive blends into the wood. The abrasive action cuts the wood fibers and creates a colored paste that acts as a filler even if the wood has small pores.

The surgeon generals' warning: practice this first. I think you will come to the conclusion that the liquid varnish must be very thin for this to work. If the varnish is too thick, you will get a spotty covering of mud from the abrasive. Remember, you are not trying to put much on the surface.

Another aspect is how much color do you put into the wood with this process? For instance, you could do this process with a strong pigment stain (say one of the Quinacridones or burnt sienna), use a very highly pigment-charged varnish, or just use a light colored varnish. There is room for some experiment here. What does Curtin do? Is it possible that the particle size of the abrasive is similar to that of a pigment? If so, perhaps you could polish, directly, with the pigment--in that case, many people are already doing this.

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Maybe angels were protecting the helpless, but I french polished a Honduras rosewood guitar filling the pores with rottenstone (ignorant old paint store rottenstone), with good results.

Re. Mike Danielson's caution about getting the resin/abrasive compound too thick, isn't there evidence on Cremonese instruments that the ground was variable, seeming to have been applied thickly (as one might a glaze ;-) ).

Dave Gardner

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Amori,

As I understand the process, the resin should be of small consequence as long as the varnish is short oil and relatively viscous.

Tripoli in the States sometimes comes mixed with wax as an automotive polish...obviously to be avoided. Good tripoli is usually available from gem cutters tool suppliers.

Rottenstone or Pozzelana Earth can be had in a variety of colors from white to orange to grey.

Have fun.

Joe

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Magister Varnish Products has a ground coat that is (according to their literature) 30-50% pumice in an oil varnish which are rubbed on. The color coats (called paint by Magister) are applied over this; so this implies that the varnish must be without a lot of color. I have not seen this material, and so I am not able to tell you the viscosity. Perhaps one of the readers can comment on this Magister product.

From what I have read, gesso was applied to lots of stuff--wood, cloth (picture canvas) before varnish was applied at the period of the famous viiolin makers. Magister says his stuff is essentially gesso except Magister used varnish to stabilize it into place while classic gesso is a mixture of white powder (lots of variety, here) in thin, warm glue. I have never read whether you can use classic gesso on a white instrument followed by rosin oil or some thin varnish and achieve the same results as the violin masters. I wish someone who has tried this would comment. Rubio tried a variation of this but his fixative for his gesso was a silicate solution rather than warm glue or varnish. I am not comfortable using a silicate solution, and think this was a wrong turn.

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"One last thing - Craig, if you're using Pumice mixed with Shellac as a ground, wouldn't that make up essentially a French Polish, which you then cover with your oil varnish? It sounds like a good procedure to me, in spite of the fact that the French Polishing literature I've read states that filling pores with pumice/shellac is necessary for rosewood and mahogany, but maple and spruce have small pores that don't require filling. I might assume that the use of Pumice in your ground has a different function than the French Polish pore filling.

This is a fascinating topic, thanks everyone."

Yes, for me also - this is a worthwhile discussion even if it is somewhat tedious wading through what would probably not take long to demonstrate firsthand were we together in a room with examples...

Salieri,

I don't think so.

The additioin of pumice is what makes this ground process NOT French Polishing, in addition to the technique of application, since it is brushed on very thin and not padded on with the very specific padding technique that is used in French Polishing. In addition is the fact that it is not an attempt to simply put a gloss back on whatever finish is already on the violin, which is what I almost always associate "French Polishing" with in relation to violin work.

Am I making sense?

I would be uncomfortable calling this French Polishing simply because it is a use of shellac.

And you are correct that I'm not adding the pumice to the ground coat simply to fill the pores in the wood.

I am using pumice as an additive to some of the things that Mr. Darnton has recommended publicly about varnishing on line.

Whether or not Mr. Darnton uses it also in the shellac sealer or ground I cannot say. I do not think he intentionally recommends it though. Even though I have lifted virtually 100% of my recent varnish methods from Darnton, he keeps some of his ground methods back, but does point towards certain things. You decide for yourself it is correct to use.

I started using it (adding it ) because when I started antiquing my violins, I thought I needed something to mimic the areas on the white violin where the oil varnish had worn away and where the original bare wood (which is usually assumed to still have some sort of original Strad ground coat - but who knows, perhaps it is simply the patina and effect of age along with whatever polish, dirt, and French Polish the past has provided?) was showing through - so I started adding both pumice and color to the ground/sealer shellac so that when I wore through the top coat of oil varnish (as I do during the "antiquing" process) I would not have to deal with bare wood but with a strong undercoat that would resist my abrasive attack and which looks like old or aged wood.

I think that perhaps accidentally I stumbled on something that also might help the finish and the stiffness of the plate - I certainly like the effect that the practice has on the look of the finished violin (antiqued or not) and the tonal properties haven't suffered even though two violins isn't enough to say with any certainty that it helps the tone either...

A lucky accident?

Though we have strayed a bit far from the original topic - I hope this helps.

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quote:


Originally posted by:
Andres Sender

CT you are quite right. The painter's method of 'glazing' is more similar to normal colored violin varnish than to what violinmakers refer to as 'glazing'.

Perhaps the terms are confusing to people who also oil paint. I started as an artist many years ago, and recall learning about the technical process of "glazing" as it is used in painting then.

The "glazing" I refer to with regard to violin making is specifically the "glazing" that Bill Fulton and Henry Wake popularized during the (geeze, was it the 1970's, my memory of that time is strangely fuzzy...) with Fultons work as a member of the SCAVM, and then H. Wake in his "Luthiers Scrapbook" where he brings the method to the attention of the general public. It is a method of layering pure ( but transparent) artist oil colors between layers of already hardened oil varnish. The glaze layer gets applied and is dull and fairly opaque - when the over layer of oil varnish hits it, it becomes transparent and glossy again.

It's main weakness is in the opacity of most artist oil colors, which has been brought up here before, as their main function as an artists oil color, is to cover (whatever is under them) easily in the context of a painting. It is a trade off I find I can live with if I maintain the use of heavily tinted oil varnish (hence the asphalt colorant - which we have discussed here in the past) and a *very thin* use of glaze...

I think that many members have a vague idea about what's going on with "glazing" but I am usually referring to a specific technique - so some confusion may result from not having one very specific technique known as "glazing" for violin makers...

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Mike says:

"I am not comfortable using a silicate solution, and think this was a wrong turn."

For what it's worth, I agree .

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Forgive me if I'm wrong, but I think this technique of sealing wood

with shellac and pumice has its' own name in French. I can't quite

remember what it's called, so I'll have to ask my French guitar

maker friend. Does anyone else know the name?

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Ok, apparently it's called 'bouche porres', which basically means

'grain filler' in French.

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Hi JOe Robson,

quote:


My short oil varnishes are 1 part resin to 0.625 parts oil.
quote:


Why not make it 1 part to 0.618?

Wolfjk

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