Lili Krakowski on wed 10 jan 07
When Ron spoke about Frit 3134 as a better replacement for Colemanite and GB
than 3124, I found myself corrected. I had gone by the Hobart Cowles recipes
I edited for CM and in the Ceramics Monthly Handbook on glazes where both
3124 and 3134 are used to replace Colemanite and GB. (Actually the journey
was longer and "we" first went to Frit 3191 (defunct) something called I
thing G 15 (?) also defunct, and then to 3134 and 3124.) I still use F34
when I can get it as direct replacement for C & GB. But definitely more
glazes included 3134 than 3124. Sorry.
But RR brought up cost, and this brings me to a question I often ask when
cost of glaze is brought up,
In the '04/'06 Bailey Catalog Frits range from $2.05-$3.00 per pound when
bought by the single pound, and $1.75-$2.35 when bought in ten pound lots. .
The highest percentage of frit I have found listed in the recipes I have is
27.6. A pound being roughly 1/2 K, a pound would help make up about 4 K of
glaze.
Now 4 K of glaze lasts me a long time. But I do not produce that much. If
I did, then the glaze would pay its way through sales.
The same question about cost in comparison to yield applies to all the
glazes that are fine with zirconium but lovely with tin.
So my question is: HAS anyone an idea of how glaze costs per pot?
Remembering that the serious producers make their glazes up in very large
amounts? IS the price of a single ingredient, e it 27% or--like tin about
10%, like cobalt carb 5% at most--a worrisome consideration?
Lili Krakowski
Be of good courage
Bruce Girrell on wed 10 jan 07
> So my question is: HAS anyone an idea of how glaze costs per pot?
> Remembering that the serious producers make their glazes up in very large
> amounts? IS the price of a single ingredient, e it 27% or--like tin about
> 10%, like cobalt carb 5% at most--a worrisome consideration?
Dear Lili,
Thank you for being of good courage and asking this question. It amazes me
how often I see a question like "I just mixed up two gallons of my favorite
glaze but added hens' teeth instead of dragon's blood. How can I save this
glaze?" appear on the list. Why anyone would risk hours and hours of work to
save ten bucks worth of glaze is beyond me. Dump it. Consider it a cheap
lesson in glaze mixing.
Using a current price list from Bailey Pottery Supply and using prices for
standard bag amounts (50 lb bags) except for opacifier in which I used a per
pound price, we can calculate the price of a 10 kilogram batch of Leach
White
40% Custer Feldspar $1.67
30% Silica 1.25
20% Whiting 1.50
10% EPK .51
add
5% Tin oxide 12.48
Total $17.41
Clearly, the tin dominates the price, being responsible for 72% of the cost.
The tin price could be cut substantially by ordering a 50 lb sack, but that
would be a $442.50 bag of material so we'll just use the per pound price.
Also, buying in smaller size lots than 50 lb bags for the remainder of the
ingredients will increase their price, but as you can see the real killer is
the opacifier.
Now, how many pots would a 10 kilogram batch glaze? Size, glaze coverage,
glaze thickness, etc. all enter into play, but let's assume that an ounce of
dry glaze material adheres to each pot. Think about glazing a pot, drying
it, scraping off all the glaze and weighing it. An ounce seems a little high
to me, but I'm trying to be conservative here. If we assume that an ounce of
dry materials is used for each pot, then our 10 kilo batch will glaze 350
pots.
$17.41/350 = 5 cents per pot
Change the ingredients around as much as you want. Add in realistic amounts
of cobalt or whatever else you consider to be expensive. I doubt that the
per pot cost will change much.
You might also think about how much time you put into your pots and whether
or not it is worth risking that time plus the time of glazing plus the time
and cost of a firing to save the cost of even a 10 kilo batch of glaze. A no
brainer in my book.
Bruce Girrell
claystevslat on thu 11 jan 07
Lili --
I started to calculate some glaze costs, and determined that
it wasn't worth my time to keep my prices up to date. There
are a few (very few) materials so expensive as to make their
us non-casual; for the most part the price of the dry glaze
materials is a small cost input to a finished pot.
Example --
My yellow glaze, Ian Begg's clear with 8% TiO2 (a non-expensive
colorant/opacifier) costs $1.49 per pound for materials.
If I make a white glaze out of it, using 8% Tin as an opacifier
I get a slightly 'hard' white glaze for $2.23 per pound. Adding
2% Cobalt Oxide (a bad experiment, I didn't like the color and it
sputtered on my shelf, but my blue-buyers bought all I made) I got
to the princely sum of $2.92 per pound.
And the zircopax-tin question is not as clear as it seems; I find it
takes 1.5 to 2 times more zirco than tin to get the same effect,
so though zircopax is only $1.45 an equivalent to tin will cost
almost $3. Like you, I prefer the tone of tin more, so I only use
zircopax in a dark glaze where it serves as an opacifier and not as
a whitener.
If I made an equivalent white glaze with zirco, it'd cost $1.45 a
pound, almost exactly the same as the yellow and save me only 78
cents a pound.
Erbium and so on are now available for prices comparable to
cobalt -- and even if you take a rare earth that requires 10%
concentration to develop color, you only get to $5.40 a pound
or thereabouts.
How much dry materials weight it takes to glaze a piece depends on
a multitude of variables, but I believe the worst I've ever done is
about 7-8 mugs to a pound of dry weight, and that was a rather
thick glaze application. Saving 78 cents a pound works out to 10
cents a mug for the cheaper materials ... not, in my mind, a good
bargain.
What' expensive is buying tons of equipment and materials you
don't actually need or use ... a mistake of which I am guilty
(you should see my stores of mason stains ...).
Best wishes -- Steve Slatin
--- In clayart@yahoogroups.com, Lili Krakowski
wrote:
>
> But RR brought up cost, and this brings me to a question I often
ask when
> cost of glaze is brought up,
>
> In the '04/'06 Bailey Catalog Frits range from $2.05-$3.00 per
pound when
> bought by the single pound, and $1.75-$2.35 when bought in ten
pound lots. .
> The highest percentage of frit I have found listed in the recipes
I have is
> 27.6. A pound being roughly 1/2 K, a pound would help make up
about 4 K of
> glaze.
>
> Now 4 K of glaze lasts me a long time. But I do not produce that
much. If
> I did, then the glaze would pay its way through sales.
>
> The same question about cost in comparison to yield applies to all
the
> glazes that are fine with zirconium but lovely with tin.
>
> So my question is: HAS anyone an idea of how glaze costs per pot?
> Remembering that the serious producers make their glazes up in
very large
> amounts? IS the price of a single ingredient, e it 27% or--like
tin about
> 10%, like cobalt carb 5% at most--a worrisome consideration?
Jon Pacini on thu 11 jan 07
Greetings All---- Hi Lili -- From my experience I have to echo the
thoughts of Bruce and Steve, the cost of materials is pretty minimal per
item when you work out the math.
I had a studio over in Kona, Hawai'i for nine years and was hooked up with a
bunch of coffee farms over there. In the months leading up to the Kona
Coffee Festival I'd make about 2000 Mugs a month. If I saved a nickel per
mug in materials, that only adds up to $100.00 a month. Granted, a hundred
dollars is a hundred dollars, but that's the level you would have to be at
to make that difference. How many studio potters make 2000 items a month???
How many make 2000 items a year???
Material costs matter if you are working on an industrial scale.The biggest
cost to a studio potter is the time/labor involved in making ware and it
won't matter how hard you try to cut your material costs if you under value
your labor costs.
Best regards,
Jon Pacini
Clay Manager
Laguna Clay Co
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