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11
Techniques / Reducing colors
« Last post by Administrator on February 11, 2019, 11:27:49 AM »
Here are a few oldies from the Craftweb archives:


Will no one stand up for the old standby, K-215 (Gold brown)? I still love using it since you can achieve pretty much any effect you want, depending on the reducing atmosphere, and your timing. You can get silver, silver-blue, brass, or gold. I especially like the "swirly" teal you get when you reduce it too long. (Actually, I hated it, but then a friend told me to call it Antique Blue, and the pieces sell pretty well.

I layer silver blue and silver green with R-61 and stamp it into an optic mold. Lots of fun. POWDER!

Gaffer black luster is a nice one, but my all time favorites are Richenbach's iris gold, golden brown, and clear silver. try sprinkling a little copper ruby over that silver glass, or under it if your using frit. you can also use silver leaf in conjunction with copper ruby and get some wild reactions which stem from the fact that copper glass and silver glass will freak out when they touch.. Also, arsnic white(r-61) will react with a silver glass in very strange way, you'll get lots of greens.. just make sure that if you want the colors to react you must have them touch each other. If you gather over the silver glass and add copper to the next gather nothing will happen.
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Techniques / Potassium Nitrate and Antiquity Glass
« Last post by Administrator on February 07, 2019, 10:35:38 AM »
A little goes a long way. I add about 2g into 250g of powder. Others just sprinkle it on straight or roll it in a bit. The effect is dramatic and creates smoking and bubbling on the piece. Nitrate helps in the batch melt so consider this a catalyst or flux for localized glass melting. Silver nitrate also does this a bit but is obviously gobs more expensive. Very fun...I have overdone it and seen some cracking due to incompatibility. Everything in moderation  8)
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Techniques / Fun with Gaffer Green Luster
« Last post by Administrator on February 05, 2019, 05:28:13 PM »
Eben Horton: I like to do r-61 powder with gaffer green luster powder on top. The reactions look like pools of water on a white glacier.

After you apply the powder let the piece get very cold and then stick it into the path of your glory hole burner's flame. (Higher velocity round burners are best) and get it wicked hot. Pull it out, and marver it, then blow it out.  Don't use gaffer enamel white for this. It's too soft.

Eric Trulson: It has another good color reaction when combined with r-232 (cranberry). They form a nice straw/gold sort of color wherever they're given a chance to melt together.

Eben again: Take a sifter and dust the lightest coating of copper ruby power over the 2nd to last gather and then apply that green lustre over it. nice reactions.
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Techniques / Simple color effects with Silver Blue
« Last post by Administrator on February 03, 2019, 01:51:06 PM »
Thanks to Scott Novota for this tip:

Try Dark Silver blue(K), with a bit of Copper Ruby(K) red frit directly on it. That is always a crowd pleaser.

And another...the Silver blue luster does some cool stuff with #2 or 3's of K-20, whatever yellow that is.
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CraftWeb Rants / Tough Love
« Last post by Administrator on February 02, 2019, 01:21:06 PM »
I started spending a good deal of time on Craftweb when I started building out my own studio some 8 years ago. I've gotten great advice and found answers to a lot of questions which were just not available anywhere else. Along the way, I started considering making my own glass. Pete Vanderlaan is a huge proponent of doing so and has 40-50 years of experience doing just that. He has held classes on making color batch attended by many of the Craftweb membership.

It was at his suggestion that I became interested in making the silver colloidal glass chalcedony and optimizing it by using his base color formula. I have a small operation but I am committed to it and followed through by working with Jim Meyers at East Bay Batch to mix Pete's unoxidized clear. Pete wants a royalty on this glass which is modest but over time might actually amount to something. After I established this contact everything went haywire.

Pete has accused me of stealing his recipe (discussed here) which we agreed I could use and has been published on Craftweb. Jim was aware of the source of the formula...we called it Pete's unoxidized clear! Now, Jim Meyers will not speak to me and Pete has banned me from Craftweb. Would he do this to a bigger player? I think he is clearly throwing his weight around and when he realizes you are not going to make him any money he will sever ties with you.

I felt the need to warn other small studio artists and provide another OPEN SOURCE means to acquire this information. I know someone who actually attended Pete's class ($$$) and with a small (but growing!) studio found him a poor source of downstream information. It's a shame...the growth of this industry is the smaller electric furnace user. This website is for everyone who wants a better organized source of the wealth of information which is out there but near impossible to find.
16
Techniques / Technique of the day...Stretched Glass
« Last post by Administrator on February 02, 2019, 12:49:57 PM »
I'm going to try and keep up with a goal of adding a technique to this board daily. More when I find a treasure trove of them. ;D The Craftweb General Discussion area is a bit of a nightmare to try and find anything. I have learned a few ways to search it and actually took a week to read the entire archive. I found so many nuggets shared in there that it seems a shame they they all stay hidden.

Here's a first...Stretched Glass or the Imperial Stretch discussed back in 2012.

Pete Vanderlaan: "Imperial stretch" is a technique of spinning a bowl after it has been fumed with stannous chloride. The spin makes the irridized fumed surface "stretch into a regular cracked fume radiating out from about four inches towards the center of the bowl out to the lip.

Important points:
- Stannous chloride is pretty nasty and highly oxidizing. Ventilation is important.
- Mix up a 30% solution in isopropanol (30g/100ml). Add some muriatic acid to help get it dissolved (just a quick splash).
- Get a Critter Sprayer with stainless steel components. This uses a Bell jar as a glass container and compressed air as the spray source. This stuff will break down aluminum and normal steel in no time. Stainless lasts but not forever...buy refurbish kits to keep you spraying.
- When spraying get it out of your area ASAP. I set up a fan that gets it into the ventilation hood flow. If you are spraying near anything steel (MARVER!) it will rust.
- Stannous likes a reduced surface. Hit your piece with a fluffy, weed burner and then spray it from a few feet away. Flash and Repeat. Don't over do it or you will chill it.
- Usually stannous is performed right before boxing, but this technique requires continued working after application. Get it on the punty and spray it before spinning out.
- Heating a stannous sprayed piece for long times in the glory will remove the irridization to a degree. It will be most successful if you can limit heating cycles in the glory...perhaps spot heating the lip using a torch at the bench.


17
Batch Recipes / Re: An attempt at a SP87 like glass batch
« Last post by Administrator on February 02, 2019, 12:01:13 PM »
I was asked about the SP87 recipe and the color base. A Craftweb post reminded me of a clue for its ingredients.
In a discussion about coloring SP color base, it was noted that soda is often added back to the base. Kenny Pieper pointed out that the color base has the following modifications to SP87 clear:

- no antimony
- the subtraction of 1.7lb. sodium nitrate from 98lb. of batch.

With this is mind, I will make a new version of the SP87 theoretical formula with sodium nitrate.  :D

The rest of this post including the Penland list of SP base color additives is in the similarly titled post here.
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Batch Recipes / The Penland Additives
« Last post by Administrator on February 02, 2019, 11:59:17 AM »
Penland Additive Formulas for 19 pounds of batch. (Dave Bross noted: I think this may be wrong, seems like an awful lot of colorant for 20# of batch on some of these)

Recall that "bone ash" in these is for a specific phosphate source that is no longer available (Bone Ash 21). I found Bone Ash on Amazon and other sources but I worry that it's just not the same. Besides, true bone ash would have loads of calcium which Dave Bross found negatively impacted melting an opal phosphate glass. I would suggest substituting a pure phosphate such as sodium tripolyphosphate (STP, STPP).

The soda ash add back is important as SP color base has a subtraction of 1.7lbs soda nitrate for every 98 lbs of batch (Kenny Pieper). The nitrate is removed to prevent oxidation in the glass.

No Melting instructions are included. Dave suggests using the colorant percentages to make colored versions of your own glass batch formula. As I move on to different colors I'll be trying and discussing the details of making these successfully.

A note on Mixing: SP color base must be mixed before using. So...you have to have a way of completely mixing up 100lbs of batch before getting started. For the colorants, add them into a separate container and mix completely before adding into the base. Try dumping a little batch into a bucket and a little colorant...mix. Repeat until all ingredients are in the bucket and then mix again...a lot (Drill with paddle bit or whatever works for you).

Purple: 200g mang dioxide, 90g soda ash.

Opal Purple: 70g mang dioxide, 15g cobalt carb, 450g bone ash, 95g soda ash.

Violet: 150g mang dioxide, 5 10g cobalt carb, 65g soda ash.

Opal Yellow: 110g cadmium sulfide, 20g sulfer, 650g zinc oxide, 70g. pot ash, 90g soda ash.

Yellow: 128g cadmium sulfide, 660g zinc oxide, 68g pot ash, 95g soda ash.

Yellow Orange (for 18lbs): 40g selenium, 650g zinc oxide, 110g cadmium sulfide, 140g pot ash.

Opal Green: 50g potassium dichromate, 20g black copper oxide, 450g bone ash, 85g soda ash.

Opal Green 2: 25g potassium dichromate, 10g black copper oxide, 90g borax.

Opal Jade: 40g black copper oxide, 20g potassium dichromate, 450g bone ash, 95g soda ash.

Turquoise: 200g copper carb, 55g potassium dichromate, 95g soda ash.

Blue: 200g copper carb, 7g cobalt carb, 25g potassium dichromate, 90g soda ash.

Med Dark Blue: 150g black copper oxide, 90g soda ash.

Opal Dark Copper Blue: 240g black copper oxide, 405g bone ash, 90g soda ash.

Lapis: 50g cobalt carb, 180g borax.

Opal Lapis: 30g cobalt carb, 10g black copper carb, 450 bone ash, 85g soda ash.

Opal Red: 128g cadmium sulfide, 64g powdered selenium, 600g zinc oxide, 68g pot
ash. 430g bone ash, 430g bone ash, 95g soda ash. To darken, add 72g selenium, 90g pot ash.

Pink (18lbs): 40g selenium, 90g cadmium sulfide, 600g zinc oxide, 68g pot ash, 80g soda ash.

Black: 231 mang dioxide, 11g potassium dichromate, 32g cobalt carb, 118g black
nickel oxide.
19
Tools / Re: Glass Calculator
« Last post by Administrator on January 29, 2019, 10:39:19 AM »
The formula in that calculator should not be attributed to Dave...that's my doing. It's a Vanderlaan formula that has been published on Craftweb save the alumina. I think it's a great starting point to make your own custom batch or as is. Add lithium if you want more working time. Remove borax and replace with KNO3 if you don't like it's corrosive effects. Test, test, test.

Glad you got a chance to play with this calculator. It's got a few modifications made by me and you wonder if they will be clear for others to use. The colorants are mostly metal oxides and expansion coefficient numbers for those in glass are lacking. Lots of people have used the numbers from a study performed on glass enamels which doesn't estimate their properties in glass effectively. The good thing is that these metals are typically used at such low percentages that any effects on expansion can be ignored or corrected easily. Check out the SP87 color base batch listing I posted...whole list of recipes for a bunch of colors to achieve with this batch. The opal phosphates also include extra sand in the recipes to overcome the effect of the phosphate. Problem with them is that they use bone ash which in its early form is hard to come by. In other words, the stuff they sell today just ain't the same. Worth a try though, but a better phosphate choice is sodium tripolyphosphate (STP, or STPP). The fluorine content in SP87 is very helpful in making this batch melt effectively as an opal phos.
I also put up a calculator for a theoretical SP87 which was made using a published analysis of this batch. I'll need to tweak it a bit after I read up on a few posts describing the SP87 color base. In it is discussed the specific things that were removed from the batch for the color base. Remember to mix the contents of the bag very well before starting. It is NOT mixed...they drop the ingredients right in the bag. It will ruin the whole bag if 10 lbs are taken out to test only to realize that the batch wasn't mixed effectively. If I sound like this is currently an issue for me, you're correct!  :-[
20
Tools / Re: Glass Calculator
« Last post by vitroholic on January 28, 2019, 12:44:32 PM »
I loaded up the calculator and fooled around with it a little.
I haven't done batch calculations since college, back when computer time wasn't easy to come by. I remember thinking it'd be cool to get the calculations put into my brother's programmable calculator to streamline the process, but of course I never did it.  :P
Still, Dave's calculator looks nice, and being open source helps with someone like me who isn't going to make any money off of my work for some time to come, if at all.
A couple of questions, though.
there's a lot of colorants left out of the tables. How hard would it be for a dope like me to add them?
I'm going to start out using SPB color base. I got the stuff so long ago, I have little info on what's in it. Without stepping on any large and sore toes, I wonder if there'd be a way to insert this formula in there? Maybe the batch calculator is something better to use with a fresh formula, or the one dave so helpfully included with the spreadsheet.
I'm still working from theory on all this, as I have to build a barn to house my studio before I can start melting anything.
If only the ground would dry up a little so I can start the foundation.
Still, I can start gathering up the knowledge and practice with formulation in the meantime
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