Jump to content
Babs

Prediction required

Recommended Posts

I was tidying up odd pots and decided o try a different glaze.

I had a recipe for Nutmeg and so I set forth, did something I NEVER do, ran a running total down side of glaze quantities to see if it was written in percentages..DOn't do this at home.

I then multiplied by 10 to get a decent trial for testing..wait for it

Nutmeg                          R.T.                    Wgt in gms

Dolomite    23.30                                   233

Spod             23.30         46.6                 233  called away to help :-((

Frit 3134     6.8              53.4                534    alarm bells

OM4             23.30         76.7                767 bigger alarm bells

Silica            23.30          100                233

and the additions to colour

I was called away again, don't ever be nice, it works against you , came back and re added the tin oxide, I think,....

OM4 threw me, ball clay is what this old lady knows this by and we also have here whiting sold as OMny carb, but I was aware of this so got the right ingredient, feeling pretty pleased with self, would think knowing the total should be  1000g all up...nope, even thought, well that's a lot of frit for a "cheap" glaze.... scraped the bottom of my container getting enough....and that's a lot of ball clay...

Anyway, I put it on the inside and top third outside of a single left on the shelf mug., fired it to cone 6 with a fifteen minute hold last night, woke up to be there to see kiln turn off 2.15am,, had to wait a bit, and the  penny dropped onto my frontal lobe!!!!!! 

SO question to you guys with the chemical slant on life, what will the result be?

I think the frit:clay went from a 1:3.4ish to 1:1.4sh, not even sure of that on this fine day..... so it will be on my shelf???

When applied it took a while to dry on pot and I was thinking about that too

Moral of the story don't run a running tally anywhere near your recipe, put ear muffs on so can't hear other peoples" dramas. Double check your maths

Don't be nice.

Have  a safe New Year

oh what do i add to make this right?  just joking but for those who like mathematical challenges.

Share this post


Link to post
Share on other sites

Interesting batch of eutectic soup. Do not have my glaze calculator handy, but from the ingredients somewhere in the satin range. Calcium and magnesium from dolomite, boron from the frit; and iron, titanium, and magnesium from the Om4. Lithium from the Gwalior spod, plus a fair amount of alumina. 

Om4 holds 35 grams of water per 100 grams to form a pliable ball. Thinned down for glaze, nearly 50 grams per 100 grams of clay. So drying time should have been much longer. Lower expansion I would expect due to lithium, clay, and alumina content. The OM4 is going to produce the color primarily.

just label the bucket: " Frankenglaze" little electricity and it will come to life.

Share this post


Link to post
Share on other sites

Everything looks within the lmits for Green and Cooper.

The boron is a bit high but the alumina is neither too high or too low.

The lithium might tip the melt a bit towards runny but my guess is for a happy accident. The silia:alumina ratio suggests, as GN anticipates, a more satin result but the magnesium is insufficent for a proper magnesia matte in my experience.

 

 

Share this post


Link to post
Share on other sites

Looking at it in Glazemaster, it should be ok, though different as Mark correctly predicts... The alkali level is higher (.26 now vs. .22), but not out of range. However, now the alkali content is dominated by sodium from the frit vs. lithium from the spod, and this changes the expansion quite a bit so there might be a glaze fit problem. The Si:Al ratio is lower (6.5 now vs 7.2) because of the added clay, but not completely out of range. The big change is in the boron - now .28 vs. .07. That will add some melting and gloss. Let us know how it looks when it comes out of the kiln.

Share this post


Link to post
Share on other sites
10 hours ago, Babs said:

I was tidying up odd pots and decided o try a different glaze.

I had a recipe for Nutmeg and so I set forth, did something I NEVER do, ran a running total down side of glaze quantities to see if it was written in percentages..DOn't do this at home.

I then multiplied by 10 to get a decent trial for testing..wait for it

Nutmeg                          R.T.                    Wgt in gms

Dolomite    23.30                                   233

Spod             23.30         46.6                 233  called away to help :-((

Frit 3134     6.8              53.4                534    alarm bells

OM4             23.30         76.7                767 bigger alarm bells

Silica            23.30          100                233

 

You were doing fine until you got to the Frit and OM4.  Looks like you got off track after getting 'called away', and multiplied your running total by ten, instead of the original item quantity on these two ...

Frit 3134   6.8  x 10 = 68   (vs 53.4 x 10 = 534)

OM4   23.3 x 10 = 233.

Share this post


Link to post
Share on other sites

Just re-read OP a little closer, and looks like you already figured out where you went wrong... so, being one who likes a math challenge,  I dropped your numbers into a spreadsheet, ran some calculations, and it looks like in order to restore original recipe percentages, you would need to increase your batch total to 8000g (for round-numbers).

image.png.4be309c1eb94fd3f127db4d0797fd8e4.png

The 'inverse %' column divides your qty used by the target percentage - to figure out what the total qty would have to be in order for the qty used to equal the desired % of total.  I picked the largest number in that column, and rounded up.  Then, in the 8000 column, multiplied 8000 by original percentage.  Last, subtract the amount you used from the number in that column, to determine how much to add to restore target percentages.

Bottom line:  Unless you think you're going to use a LOT of that glaze, you might want to just toss it and start over.

 

Edited by Rockhopper
Additional note: My calculation doesn't take into account any glaze already used - final results would still be slightly off from original, depending on how much you've already used.
Babs and C.Banks like this

Share this post


Link to post
Share on other sites

This glaze 'adventure' reminds me of something from a Greg Daly book. He has a section on random glazes and how we can learn from odd/unexpected ratios/results.

I enjoy trying understand eutectics so the perspectives here are helpful.

It might be fun/educational to share a random glaze or two.

Edited by C.Banks

Share this post


Link to post
Share on other sites

yes, random indeed.

I have Greg Daly's book and have "randomly" used a few .

It's interesting and as long as you use biscuits to save shelves , fun.

 

takes away the fear of playing.

Highbridge, the colorants were RIO, Tin and major Yellow Ochre

by cones my kiln didn't quite get a touching toe 6

I'll place a pic, in a few mins.

Rockhopper, knew there would be a maths freak lurking. Potters come with many obsessions. Thanks. All

Share this post


Link to post
Share on other sites

5a484a4b569d6_RandomNutmeg.jpg.3f6d0e6bc349cfe5064718b4ea012a50.jpg

High Bridge

RIO 1.07

Yel Ochre 3.24

TIn Oxide 4.85

Bentonite 1.94.

By the looks I did not double the tin oxide.

The photo makes it much more shiny that it appears just sitting on a table. It's actually much more of a blah brown, no interaction with the lower glaze, a Rockingham brown.

I'll try again with a batch before going to the 8000g batch though I appreciate the effort spent doing the Maths.

I'll go look for an image of Nutmeg first.

Share this post


Link to post
Share on other sites

Yip I was smiling so wide my face ached all morning. I was hopeful because of  the amount of Ball clay.  It was at the side of the top shelf I had visions of it dripping all the way to the bottom. If anything it was a tad underfired.;)

So in the scheme of things, Glazenerd was about the mark.

Amazingly i get where you're at, rockhopper, with the maths. will do a test of Nutmeg to see if I really want this glaze, this batch I think is destined to be mixed with a high gloss one which I do not like, just played with randomly..

B

Share this post


Link to post
Share on other sites
Just now, glazenerd said:

Bentonite is redundant with that much OM 4 included. Not sure the tin is all that useful, would be tempted to replace it with titanium. Perhaps a little bleeding would make for a nice touch.

Not sure I'll go mixing this again Nerd, but I may add a bit of titanium, why not, she says.., or spray some on in patches.

Kiln gods must have been on my side.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use.