Beebop

I have recently carried some successful trials using saggars to produce cone 6 copper red reduction glazes in an electric kiln.  I generated a reduction atmosphere by adding a small amount of black iron oxide mixed with powdered charcoal to the bottom of a saggar with a test piece painted with Selsor red copper reduction glaze (see formula in "The Complete Guide to Mid-range Glazes " by J. Britt pg 100).  I started with a copper red cone 6 glaze because it is easy to see if there is reduction; red=reduction / green=no reduction.  The iron oxide/ charcoal mixture reacted to produce a reducing carbon monoxide atmosphere within the saggar, as the electric kiln was fired to cone 6, which changed the glaze oxblood red (see attached photo).  The atmosphere in the kiln remained oxidizing so that test patchs of the same glaze painted on the outside of saggar remained green.
I hope that by sharing these results I can generate feedback on this this technique.
 

Hi all, just wanted to follow up for posterity and with gratitude.  I followed the advice to Dremel the chunks and and dab to fill and it worked pretty nicely.  Difficult to reapply a consistent amount of glaze, but it's good enough.
As to the root of the problem, I re-sieved and did something I've never done before: cleaned out the glaze bucket.  I always sieve back and forth, ending up in the old bucket that has 5 years of crust all along the sides.  This time I cleaned all the crusted glaze off.  I suppose I could have scraped and mixed it in well, breaking up chunks and I may do that in the future.
Cheers!

Wanted to give an update on this question. I used a Drexel to grind off the rough marks where it looks like something ran down the side of the box. I took these spots down to the same level as the glossy glaze since they were raised. I then applied new glaze to these areas. I used the alumina and wax again on the lid and rim but this time I applied a very light coat and even used a paper towel to wipe any off that had not dried by the time I was finished applying it to the edge.
 
I refired it successfully! The glaze blended in beautifully and no runs! You can't actually tell I had to grind off some and reglaze it. The top didn't stick either GRIN. I fired the other lidded box for the first time as well and doing the alumina and wax like I did worked perfect on it too, no runs, marks or stuck lid!
 
So I think my original problem was just too much wax so that it ran as it heated up and the alumina stuck to the glaze and was fired right into the top layer of it. Thank you everyone for your help.
 
Terry

I think that in the earlier days of cone 5/6 work this was true to some extent, but not any more. The development and marketing of cone 6 glazes prior to 7-8 years ago was very much geared toward making imitations of classic cone 10 glazes. I think this approach was a bad way to do it, though, because it classified cone 6 work as something that was less desirable. It was the poor man's cone 10. It was something you were forced to to if you didn't have access to a gas kiln- the realm of hobby potters, not professionals. However in the last 7-8 years, things have changed considerably. Now cone 6 work very much stands on its own, and is likely more common than cone 10 not just among hobbyists but also professionals.
Plus you can't just drop some boron into a cone 10 glaze and have a cone 6 version. Most all classic cone 10 glazes were fired in reduction, and reducing the melt is only part of the process. Mimicking the look of reduction requires additional changes in chemistry and often makes it impossible to make an equivalent cone 6 version, otherwise we'd have cone 6 shino and tenmoku glazes that are indistinguishable from their cone 10 versions, which is not the case. Since the glaze manufacturers embraced cone 6 glaze chemistry as its own thing and started to explore what could really be done with that chemistry, we have seen some really amazing glazes come to market. The variety of cone 6 glazes now dwarfs what has been been done in cone 10 work.
Personally, when I made the switch from cone 10 to cone 6, I approached it from the standpoint of modifying my tried and true cone 10 glazes. I quickly realized that I was taking the wrong approach. I find cone 6 formulation the be very different than cone 10 formulation, mostly because materials like frits are very powerful compared to most of the standard materials we use at cone 10. It still blows my mind that we can make glossy glazes with 24% EPK in the recipe. Plus the color palette that we can do at cone 6 is huge, and easier since we can use stains that aren't stable at higher temps. I actually find cone 6 formulation to be easier than cone 10.
Why cone 6? No idea. However if we really wanted to conserve energy and extend the life of our kilns, we would be firing at cone 3. We can still make vitrified bodies using feldspar at cone 3, and element life would be fabulous, probably 200 firings instead of 150. If I was working alone and didn't have a community studio, I would develop a cone 3 porcelain and glazes. There's no reason not to. I think we're probably stuck at cone 6 for a good long time, though, because we are at the mercy of the commercial suppliers, and they've got a good thing going at cone 6. I hope that we'll see more schools switch from cone 10 reduction to cone 6, because that is what most of their students are going to be doing when they graduate. They could still use their gas kilns, but cut their firing costs in half.
Sorry for the long post. I spent my first 16 years in pottery working at cone 10, and the last 14 years have been at cone 6, so I have a lot of opinions on the subject. I could write pages and pages about it! Switching to cone 6 electric was the best thing I've done for both my business and the development of my work, but I totally get why cone 10 gas firing is better for some people.
 

No I wouldn't, could very well land up with speckles as copper ox. If speckles aren't an issue for you then reduce the amount by about a 1/3 as copper ox doesn't contain the CO2 that the carb does. Actually that would be 1/3 by weight.

Another Magma vote -it cures all settling issues with a very small amount needed.It can float a brick

If these were my glazes I would calcine some of the kaolin in the first recipe. For the ones with bone ash, I'm wondering if the bone ash (real or tricalcium phosphate?) is gelling the glaze and tricking you into adding more water which in turn would cause more shrinkage as the raw glaze dries causing the crawling. Have you tried different SG's of those ones and seeing if raising it reduces the problem? Worst case scenario I would get some Magma (Brackers sells it) and add a small amount of it to those bone ash glazes. (Magma needs to be made into a jell then a small amount of that is added to glazes. It helps stop glaze cracking and crawling but does slow down the drying time. It is also a great floc.)
 

Just a comment here, crawling can often be the result of the fired glaze surface tension preventing its ability to heal so cracks developed early on can exacerbate the issue. Calcining part of the epk often can help with the shrinkage and help with the early formation of cracks. Interestingly ball clay is know to shrink more,  but does not necessarily translate to more early formed cracks maybe because it is more plastic or has a more favorable fired glaze surface tension or both so you might have an idea worth testing.

We are permitted to create pottery at the mercy of our industrial overlords.

There was a recent thread where glaze eutectics was brought up. Stemming from that was a link to an article by Robert Magnuson in the Feb 2018 Ceramics Monthly which contained a link to a eutectic calculator, "EuCal",  he created. Magnuson discusses an interesting aspect of eutectics, to quote from the article:
"One of the most interesting aspects of eutectics isn’t how they melt, but how they solidify. When a eutectic mixture cools from the molten state, the individual components all stay molten together until they solidify. When they do, a transparent glass is formed. If the molten glaze contains ingredients that are not part of a eutectic, these ingredients may solidify separately while the glass is still liquid, leaving tiny crystals suspended in the glass, producing opacity and other effects in the final glaze. But, if a glaze contains only eutectic mixtures, a transparent glaze will result.
Very few glazes are based around a single eutectic and most incorporate both alkali (R2O) and alkaline earth (RO) oxides. Any combination of the eutectics of Na2O, K2O, and CaO (see left) will result in a transparent glaze. For such a neat trick, it’s surprising you don’t hear about it more often. If you have ever tried to formulate a fully transparent glaze by trial and error, you know it isn’t easy to do—unless you know this trick."
Since the time of that publication Magnuson has updated and revised his EuCal. Version 1.8 added borate eutectics for the alkali fluxes and the latest version, 1.9, added a calcium borate eutectic. This could be very useful as it now brings mid and low range glazes into play with the calculator. There are some provisions, see the read me file linked below.
Given that not everyone has access to the links in the article Jennifer Harnetty asked Magnuson for permission to link the read me file plus the eutectics calculator here to which he very kindly agreed to. I've added the links to the updated version below.
I realize this isn't an area that gets a lot of discussion but perhaps as time goes by as more people get familiar with the calculator it can be utilized as a stand alone piece of software or perhaps in tandem with Stull charts. Lots of food for thought here.
Link to the Feb 2018 article here:  https://ceramicartsnetwork.org/ceramics-monthly/ceramics-monthly-article/Techno-File-Using-Eutectics 
Link to the User File here:  https://ceramicartsnetwork.org/docs/default-source/default-document-library/eucal_1_91_user_guide.pdf?Status=Master&sfvrsn=a5d9b703_5/ EuCal_1_91_User_Guide.pdf
Link to the EuCal here:https://ceramicartsnetwork.org/docs/default-source/default-document-library/eucal_ver1_91.xlsm?Status=Master&sfvrsn=6fc99709_9/EuCal_ver1_91.xlsm