Kiln contamination from bad mandrels?

[Dasi]

I use a lot of DH and I have discovered that the pressure of the propane and how much propane is still present in the tank alters the reduction effects on my beads. Years ago I started a diary of my daily beads. I got very frustrated because I was not always getting consistent results so the pendants would match the earrings for production.
This is what I found:

Different torches are easier and harder to get the best reduction. BUT they all work....

The pressure of your propane needs to be adjusted every time you torch for the proper pressure at the torch.

This was the hardest to diagnose. As the propane tank empties, my reduction results get less predictable. I have started refilling my propane tank when my tank is at 1/4 full or moving it to my gas grill to use up the remainder. This has solved the problem. I even took a scale outside and tracked the weigh of the propane tank to the reduction success. There was a direct correlation... I know it sounds crazy but I have no problems with unpredictable results if I work with a full propane tank and my regulator has been correctly set.

I now switch off between boro and soft. I work in cycles of my propane tank. When it is full I work soft. When it empties to about half, I switch to boro at my other work station ( unless I have an order to fill) I keep 3 propane tanks on hand just if I need to work soft. One is usually hooked to the grill. I get about 6 weeks on a tank if I am working full days getting ready for shows.

I also found counting helps. There is a very small window that reduction works best at. The bead needs to be just right. Not too cold or hot. Not a test and then back out and back in. But patience to cool to the exact temp and color and then a reduction flame and a few twirls, done. I find if I miss the window the reduction is just not perfect. A little O2 and start over but it never is quite the same. Now I count and know exactly when by watching the glow. I sound crazy and ADD..... but it works for me.

I have wondered if propane can partially separate?

[Gila]

Heather, your attention to detail is inspirational.
Thanks for being so 'tuned in' and sharing your powers of observation.

[Dasi]

Originally Posted by Gila

Heather, your attention to detail is inspirational.
Thanks for being so 'tuned in' and sharing your powers of observation.

you were at the gathering? I think we met.

[PittsGlass]

Dasi,

Very insightful information. This is one case where ADD really helps solve issues. I like the scientific approach you took going as far as weighing the tanks.


Another artist who used to frequent here found that the location you purchase the propane from can make a difference. If you are trying to bring up the metals, a "dirty" propane can be more effective. Places that don't turn over their product as often are the best places to buy.

[Dasi]

Originally Posted by PittsGlass

Dasi,

Very insightful information. This is one case where ADD really helps solve issues. I like the scientific approach you took going as far as weighing the tanks.


Another artist who used to frequent here found that the location you purchase the propane from can make a difference. If you are trying to bring up the metals, a "dirty" propane can be more effective. Places that don't turn over their product as often are the best places to buy.

Funny...... I have 3 places to get propane and I will only use the one place because I have seen sparks going through the torch from the other 2 places. Dirt!!! I want it clean. I did a lot of gas grill cooking to get rid of the propane when I saw the sparks in the flame from the torch. I am so picky.

I have torched with Butane and I got some wonderful reduction on my silver glass with butane. It is a very dirty fuel. Maybe I need to rethink the dirty propane???? I used butane when I was torching in Israel since propane is not easy to get.

[loribeads]

What I don't get is that in the same beadmaking session I can get dots that hold their luster but spacers that lose it.

I think I will just return to my beloved striking glass.

[AKDesigns]

I think your kiln is even hotter than the pyrometer and your controller says it is. Have you tried making pressed beads like lentils or nuggets? I found that round beads lose reduction much easier than pressed beads. I don't know if it's the shape or the fact that pressed beads are prone to being cooler when you reduce so the reduction sticks better. I had to lower my kiln temp so that I didn't lose reduction on my round beads.

So if you want to do a little experiment, try making three or four reduced pressed beads and put them in the center of your kiln and use the lowest temp. that you have used so far. Make some beads of whatever you want to make that day but save a little room in the center of the kiln. If you have some old Terra or some of the new Fast Striking Terra, make a couple of small, unencased barrels at the end of your torch session and strike them to a nice pastel and put them in the center and run your schedule. Make sure your annealing temp doesn't shoot up at all from that garaging temp.

So I'd be curious to see:
1. If you keep the reduction on the pressed beads
2. If your Terra beads kiln strike at all.

[PittsGlass]

Originally Posted by AKDesigns

I think your kiln is even hotter than the pyrometer and your controller says it is. Have you tried making pressed beads like lentils or nuggets? I found that round beads lose reduction much easier than pressed beads. I don't know if it's the shape or the fact that pressed beads are prone to being cooler when you reduce so the reduction sticks better. I had to lower my kiln temp so that I didn't lose reduction on my round beads.

So if you want to do a little experiment, try making three or four reduced pressed beads and put them in the center of your kiln and use the lowest temp. that you have used so far. Make some beads of whatever you want to make that day but save a little room in the center of the kiln. If you have some old Terra or some of the new Fast Striking Terra, make a couple of small, unencased barrels at the end of your torch session and strike them to a nice pastel and put them in the center and run your schedule. Make sure your annealing temp doesn't shoot up at all from that garaging temp.

So I'd be curious to see:
1. If you keep the reduction on the pressed beads
2. If your Terra beads kiln strike at all.

I hadn't thought about the shape playing a part as well. That makes sense.

I was under the impression that most held a lower garage temp (900)and went up 10-20 degrees for the anneal, and still have had success. However, I have no idea the range of shapes that are being made, so very hard to compare. So darn many variables with reducing glasses.

I do know the kiln to be true to temp in Karolen's case. We used two pyro's here and the third on her end. It runs about 5 deg below displayed temp.

[AKDesigns]

Originally Posted by sunflower33

I did check temperatures with an independent pyrometer. It showed that my kiln was running about 50 degrees hotter than what it said on the kiln's read-out. Mike and Pam at Glass Hive couldn't figure that one out, since the pyrometer in my kiln is supposedly a good one, from a good working batch of pyrometers. I wonder if contamination can cause the pyrometer to mis-read temps, like maybe it got coated with iron and doesn't work right.

I adjusted my kiln temperatures 50 degrees to compensate for this, but still had the same problems.

Originally Posted by PittsGlass

I do know the kiln to be true to temp in Karolen's case. We used two pyro's here and the third on her end. It runs about 5 deg below displayed temp.

She said 50 degrees. So when she says she used 820 degrees is that really 820 or 870? Either way, reduction shouldn't really burn off at either of those temps so now I'm at a loss if you say her temp is really a known factor. I'm at 900 for reduction glass and any striking glass that can kiln strike and I think my kiln is running a tad lower. Nothing burns off for me now. At 960 I did have a problem with round beads and any raised stringer work, especially with Aurae. Before I figured out the problem I had done a whole set of non silver glass rounds with Aurae scroll work on them and when I took them out of the kiln the next day all the reduction was burned off the stringer work.

[Dasi]

Originally Posted by AKDesigns

She said 50 degrees. So when she says she used 820 degrees is that really 820 or 870? Either way, reduction shouldn't really burn off at either of those temps so now I'm at a loss if you say her temp is really a known factor. I'm at 900 for reduction glass and any striking glass that can kiln strike and I think my kiln is running a tad lower. Nothing burns off for me now. At 960 I did have a problem with round beads and any raised stringer work, especially with Aurae. Before I figured out the problem I had done a whole set of non silver glass rounds with Aurae scroll work on them and when I took them out of the kiln the next day all the reduction was burned off the stringer work.

That happened to me a few years ago. I wiped the beads clean of all kiln dust but I did not take them off the mandrels. I took them back up to 950, pulled them out the kiln and just reduced them again after a slight additional warming in the flame. I keep my kiln at 930 for silver glass.

[fyregallerie]

I garage much lower - like at 720 take up to 929 for 1 hour down to 805 for 3 minutes then down to 500 and off and dont have problems

[AKDesigns]

Originally Posted by Dasi

That happened to me a few years ago. I wiped the beads clean of all kiln dust but I did not take them off the mandrels. I took them back up to 950, pulled them out the kiln and just reduced them again after a slight additional warming in the flame. I keep my kiln at 930 for silver glass.

Yes, that's how I fixed that set too.

[sunflower33]

Wow, all the great responses here! Thank you everyone for your ideas. I'm still taking it all in.

The propane level in the tank is very helpful, thank you so much for sharing that. I just finished a tank of propane that I'd been using for a few months, and as it got lower my beads were losing metallic luster (hence this thread I started!). I just put a new tank on a few days ago - although it's only a half-filled tank - and my luster is better. I'll check my tank pressure too.

Pam - thanks for letting me know about the charcoal. I will try a deeper pot and larger amount.

About my kiln temperature - it WAS running about 50 degrees hot, until I sent it back to Glass Hive for the rebuild. My controller was off so they re-calibrated it. It wasn't a pyrometer problem. My kiln temperature is fine now.

The shape of the bead does make a difference, thanks for pointing that out. I agree that spacers are the hardest to get and keep reduction on. And Aurae does seem to be one of the trickiest.

Now for the good news I'm having really good luck with my metallic glass, even the spacers, during my last two torching sessions. I've got a set of 8 or 10 Gaia spacers finished that came out beautifully. I even made a Helios spacer and left it garaging in the kiln for hours, and it lost no luster, it's gorgeous. I've been working the glass a little hotter and making sure the area around the bead holes is hot enough to get good reduction.

During these past few days I've been cleaning my garage/studio. It's also the household storage place, so I finally got a bunch of boxes of old stuff to Goodwill and threw out stuff, I even found a black widow in the corner and got her and her egg sacks out! I think doing a feng shui of the studio is helping, it does make me feel better.

Somehow, between the kiln rebuild, temperature adjustment, new mandrels, studio shui session, removal of liver of sulfur and other stuff, fuller propane tank, and working my glass a little hotter, the problem is working itself out!

I'm so happy and relieved that I may in fact be able to continue making the metallic beads I love so much. I'm still doing testing and shui-ing the studio... but I'm hopeful finally!

[GLASSFREEK]

I am very glad to hear some good results are starting to return. I hope it keeps on shining!