Scavo - traditional Italian glass aging technique

[Kevan]

In the Feb. issue of Lapidary Magazine there is an article by Ann Davis about how to antique glass beads to look like they were excavated from the ground after centuries. They have that look of mineral deposits that have adhered to the surface of the glass like you would see from an eqyptian tomb or something. I haven't tried it myself, but I'm going to get some of the ingredients and see what happens.

Here is a link to a picture of a bowl with a scavo technique, but this doesn't look like the one in the magazine. I'm going to try to scan a picture as soon as I can figure out why my scanner says it's not plugged in. It's got a light on inside of it soo....

http://www.guild.com/artitem/16315.html

The article says there are several ways to do this, you can dip it in white sand if you want, but she created this techinque by mixing 1 part potassium nitrate to 2 parts whiting (Calcium carbonate). The potassium is tree stump remover, which you can get in any hardward store, but the whiting has to be really pure from a ceramics studio supply place. (Postassium nitrate is a caustic so take care with it. Evidently the gases are minimal when heated)

You grind like one teaspoon of potassium and two teaspoons of whiting together in a mortar.

This works best on large beads. The picture is a simple plain vessel which would be perfect. I think a goddess would be too. Make your bead and while it's still red sprinkle the scavo over it in clumps. It will sizzle. Heat the bead to melt it for just a few seconds. You can keep adding more until you get the build up you desire. Anneal it like ususal.

Evidently you can add enamels to the scavo and reduction frits, whatever you want.

Once they are cool, use a soft toothbrush and some liquid soap to remove any loose scavo.

[MikeAurelius]

OH GOD....STOP!!!!!!!!!

Don't do this, please! Using this technique is about the most unsafe thing a beadmaker or glassworker can do.

Potassium Nitrate is EXTREMELY hazardous and should be used ONLY OUTDOORS. NEVER EVER EXPOSE POTASSIUM NITRATE TO A FLAME - the fumes generated are hazardous to breathe.

PLEASE PLEASE PLEASE DO NOT USE THIS TECHNIQUE!!!!!!!!!!!!

[Kevan]

OH GOD....STOP!!!!!!!!!

Don't do this, please! Using this technique is about the most unsafe thing a beadmaker or glassworker can do.

Potassium Nitrate is EXTREMELY hazardous and should be used ONLY OUTDOORS. NEVER EVER EXPOSE POTASSIUM NITRATE TO A FLAME - the fumes generated are hazardous to breathe.

PLEASE PLEASE PLEASE DO NOT USE THIS TECHNIQUE!!!!!!!!!!!!

Really??? Damn. It looks so cool. Does anyone know this Ann Davis beadmaker? She says in the article that for occassional use the gases are negligable, but if you are going to do it alot you should wear a respirator.

Seriously, if it's bad I don't want to do it either.

[jacki]

Well, I did try it after reading the article. And was happy with the results. On the down side, it made a huge mess! The mixture sputters and spurts and spews residue from the highly caustic substance ALL OVER the surrounding So visualize probably hundreds of scraps of rods with this crap dusted nicely over it.......

I am planning on doing it again, but a bit better prepared. I will do it outside, by pulling out a small auxillary torch. I will use a designated box for containment, to keep the residue from contaminating the area, and keep the cats and dogs from getting into it. AND wear a respirator AND a face mask. (I did wear all that on the first try, but was not prepared for the mess it made on my fine collection of scraps and rods and choice stringers on the table!)

Also, it does continue to work, you need to scrub it out of the surface of the piece. When you do this, it shows a bit more of the degraded texture. Plus, you REALLY want to get this clean, and it is quite porous. Imagine wearing it on your skin....

Jacki

[Kevan]

Well, I did try it after reading the article. And was happy with the results. On the down side, it made a huge mess! The mixture sputters and spurts and spews residue from the highly caustic substance ALL OVER the surrounding So visualize probably hundreds of scraps of rods with this crap dusted nicely over it.......

I am planning on doing it again, but a bit better prepared. I will do it outside, by pulling out a small auxillary torch. I will use a designated box for containment, to keep the residue from contaminating the area, and keep the cats and dogs from getting into it. AND wear a respirator AND a face mask. (I did wear all that on the first try, but was not prepared for the mess it made on my fine collection of scraps and rods and choice stringers on the table!)

Also, it does continue to work, you need to scrub it out of the surface of the piece. When you do this, it shows a bit more of the degraded texture. Plus, you REALLY want to get this clean, and it is quite porous. Imagine wearing it on your skin....

Jacki


I might try the white sand method. That can't be any worse for you than glass. Can it???

[Rebekah]

You can also try Brent's magic technique, but it's messy too.

Bek

[Darlene Balkcum]

Mike,
thanks for the info... I was going to try this "Scsvo" but not now!!!!!
I love making beads and want to be able to make them for a long time.

When taking a class with Steve Belle she showed us how to get an aged look by layering blobs of enamels randomly on the bead then slightly melting them in. I like the look of her ancient beads so I guess I'll stick to that for now.
I can handle the enamel safety issues.
Darlene

[Kalera]

You can also try Brent's magic technique, but it's messy too.

Bek


And highly toxic, evidently.

You might try rolling your bead in powdered clear glass, instead, and only partially melting it in.

For an antique look, I use ground glass or sometimes I fume with antimony trioxide, which is also toxic but easier to contain.

Size 0 frits are very close to powder but coarse enough to not as easly go airborne. They also don't clump like powder. Using a reducing transparent also gives you the option of adding a metallic "antique" look.

Some of the Caliente cane has an antique look; the amethyst and the antique aqua (I think that's what it's called) both have a wonderful bubbly crusty pitted look that is perfect for pieces you want to look ancient.

[Rebekah]

Woops. Yeah, I went back and read that. Thanks for the nudge, Kalera.

I do have powdered clear, so maybe I'll give that a try.

Rebekah

[cghipp]

What about using baking soda?

Courtney

[Kevan]

What about using baking soda?

Courtney

Baking soda is ok. They use this in place of salt in glazing now. It does not give the exact same effect. Similar, but not the same.

[Antoñio]

Does anyone realize that the sunflowers in Kevan's footer are actually from a watercolor painting of hers?

(Sorry hon....I just had to brag you up.)

She's gonna hate this post. (insert evil laugh and erie organ music here)

Antonio

[!ngridh]

Thanks for this thread too... I think that combining them all it makes for enough information.

I make my own clear powdered frit so I could use that and enamels and I have pixie dust and I have old metallic powders left over from ancient days in polymer clay... The more information the merrier we will be! thanks all

[dogmaw]

Does anyone realize that the sunflowers in Kevan's footer are actually from a watercolor painting of hers?

(Sorry hon....I just had to brag you up.)

She's gonna hate this post. (insert evil laugh and erie organ music here)

Antonio

What a cheat, she changed the picture! :lol:

Thanks for all the safety info guys. Don't think I will be trying anything that toxic right now.

[pam]

Kevan, just for further info, in case you need it.

Potassium nitrate is a component in explosives and is an explosion hazard when heated above 530 degrees C or 986 degrees F. Aside from the explosion and flammability issues, there are serious health hazards AND A NORMAL RESPIRATOR IS NOT SUFFICIENT PROTECTION. The only protection recommended for this chemical is a full-face supplied-air respirator approved by MSHA/NIOSH, operated under positive pressure, or an approved self-contained breathing apparatus operated under pressure-demand or other positive pressure mode. Your normal filter-type respirator is no protection.

Contact lenses MUST NOT be worn when using this chemical.

It is a strong oxidizer and dangerously reactive and shock sensitive when mixed with organic materials (calcium carbonate is not considered to be organic) and many other materials. It has violent reactions with reducing agents, chemically active metals and charcoal, among others.

The short term effects of potassium nitrate include eye and skin irritation, respiratory tract irritation, coughing and wheezing. High levels of exposure can interfere with the blood's ability to carry oxygen, causing headaches, dizziness, cyanosis, and methemoglobinemia, with blue color to the skin and lips. Higher levels can cause breathing difficulties, collapse and death.

There is some evidence that long term exposure to potassium nitrate can damage a developing fetus.

Potassium nitrate is a combustible solid that produces poisonous gases in a fire and fire personnel are warned to withdraw to a safe position if the fire cannot be immediately cooled and suppressed. This is dangerous stuff, and the professionals are warned to be very cautious.

I have always wanted to try scavo, but hey, some things are just not worth it.

[beachbeads]

You can also get a really cool effect leaving beads in etching solution for a week or more. I call it " my almost Scavo"! It is really cool if you use fingernail posih on part of bead also as it etched deep around polish leaving the polished area raised. Be sure to soak in baking sodo and water solution after rinsing off etch solution as it will continue etching. My favorite base beadfor this is opaque colbalt blue base decorated. . Some frits will stay raised with this techinique also. Sheila

[Bunyip]

Potassium nitrate? They call it saltpeter. Major component (oxidizer) in a handy little concoction known as "Gunpowder". You can also make a fancy smoke bomb when you mix it with good old fashioned sugar.

I burned a lot of this stuff as a kid... Glad I got off so easy...

[Kalera]

Something I've learned relatively recently (and by complete accident) is that fine-grit silicon carbide will also bubble and pit the surface of glass. I have no idea whether it's safe to heat... I will be asking my chemist friend before I pursue it further, but preliminary research seems to indicate that it's fairly safe. It appears that the glass boils because of a reaction to the silicon carbide, while the silicon carbide itself does not vaporize at glassworking temperatures.

More experimentation is in order, to make sure the glass was in fact boiling in reaction to the silicon carbide and not due to some other contaminant.

[beadysam]

Saltpeter - don't they use that in some sort of food preparation? Sausages or something?

[LouiseI]

Has anyone tried using the white sand? I'm curious to see what the result looks like ;)

[Glass Monkey]

I am going to try the sand since I live in one big sandbox.

[TheMaster]

You can also try Brent's magic technique, but it's messy too.

Bek

I never mind it being messy, it is beautiful. I like it very much. I have read that it is toxic. How is it, please explain.