John Post on sat 17 jan 98
Hi Ron,
Post's PMSP-4 glaze is mine, but the recipe you listed isn't correct. I
submitted it to the the glazebase a while back and somehow it got posted
incorrectly. I sent an e-mail to Richard Burkett about the problem some
time ago. I'm not sure what happened after that. Anyway, here is the
correct recipe with some of the variations that I use...
+++++++++++++++++++++++
+++ PMSP 4 Base +++
+++++++++++++++++++++++
Range: 6-8
Firing type: Oxidation
Glaze type: Stoneware
Surface: Gloss
Testing: Personal Favorite
Date: 11/12/96
Frit 3134 1016 25.4%
Nepheline syenite 320 8 %
Wollastonite 784 19.6%
EPK 900 22.5% Hazard!
Flint 980 24.5% Hazard!
-------- ------
4000 100 %
Superpax 400 10 %
Variations:
Clear - Do not add an opacifier, glaze is water clear without one.
Light Yellow- add tin oxide 7.5%, Mason stain 6450 10%
Light Aqua Green - add tin oxide 7.5%, copper carbonate 2%
White - add 15% superpax or 7.5% tin oxide
Light Purple - add tin oxide 7.5%, .325% green chrome oxide Cr2O3
Dark Green with Speckles - add tin 7.5%, copper carb 8%, granular rutile 3%
BubbleGum Pink - add tin oxide 7.5%, Mason stain 6001 5%
Black - add Mason stain 6600 10%
Dark Gray - add Mason stain 6600 5%
Notes:
The white variation with tin will turn pink if there is any chrome
present in the firing.
Cost: $ 2.11 per kg glaze
$ 8.44 per 4000 g batch
===========================
Chemical Analysis
===========================
Na2O 0.18 Al2O3 0.35 SiO2 3.44
K2O 0.01 B2O3 0.27 ZrO2 0.17
MgO 0.02
CaO 0.79
Alumina:Silica ratio is 1.00 : 9.91
Neutral:Acid ratio is 1.00 : 5.86
Alkali:Neutral:Acid ratio is 1.00 : 0.62 : 3.61
Expansion coefficient: 68.9 x 10e-7 per degree C
Oxides causing abnormal expansion effects: B2O3
>You wrote...
>This glaze only totals 93.56 - am I playing with a full deck?
>
>On the subject of bubbles - I don't know much about this subject - but - I
>am beginning to think this is not a problem of the CO2 coming out of
>whiting - i notic that Louis doesn't either - and her is a glaze with the
>only siniicant Loss On Ignition in the clay - maybe 15% at most. I have
>noticed in my own experiments the same thing - bubbles in glazes with
>wolastonite instead of whiting. Are there other factors involved?
>
>
>I an going out of town for tree weeks so I can'r persue this now - but when
>I get back (Feb 11) I would like to explore this further.
>
>Ron - would you remember to resend me this post when I get back - please!
>
>>First I would like to thank Ron Roy for all the time he takes to respond
>>to the group. I read all of his posts and have learned a great deal.
>>Sometimes I feel like a kid sneaking into a movie theater.
>>
>>I have just tested a batch of Post's PMSP-4 clear glaze from the
>>GlazeBase at cone 6. It came out cloudy, and when I whipped out my new
>>field microscope (another great idea from the group) I found that it was
>>full of tiny bubbles. The comments on this glaze states that it is
>>transparent with no bubbles. How did I screw this up?
>>
>>Post's PMSP-4
>>cone 6-7-8
>>clear gloss
>>
>>Ferro Frit 3134 40.13
>>Wollastonite 15.73
>>EPK 18.06
>>Flint 19.66
>>
>>I also tested 2 white variations that came out great (no bubbles) and 1
>>purple variation that came out grey, oh well.
>>
>>Ron Wright
>>Shiresham Pottery - Chicago
>>http://www.concentric.net/~wrright
>
>Ron Roy
>93 Pegasus Trail
>Scarborough,Canada
>M1G 3N8
>Evenings, call 416 439 2621
>Fax, 416 438 7849
>Studio: 416-752-7862.
>Email ronroy@astral.magic.ca
>Home page http://digitalfire.com/education/people/ronroy.htm
>
>
John Post
jp6mchp@moa.net
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