Martin Howard on sat 17 feb 01
Clayarters, especially in the UK, may have wondered why some frit analyses
are given in, for example, Potclays Frit Pamphlet and Johnson Matthey's
Select Catalogue (Page 5 in Issue 2), but not others.
Both companies have co-operated in providing as much information as they
have been able to glean from their suppliers. Potclays states:-
have not been able to get the formula from their UK office.
I have asked that we retry but failing that we will try to
track it down in Spain.
The 2266 frit is the Ferro 3110 frit. This was obtained from
UK Ferro company who bought it for us from Ferro Holland.
Ferro Holland have discontinued manufacture. We have been
told we can get it from the USA but it is ten times the price! I'm
finding a U S supply source and will find both price and formula
when I visit there in April.>
frit mentioned by Hewitt and also published by Andrew
Holden.
Low Exp. Mol Weight 535
CaO 0.35 MgO 0.27 Li2O 0.19 ZnO 0.19;
Al2O3 0.43 B2O3 1.38
SiO2 5.73>
Lee Jones of Johnson Matthey has sent me, after some chasing of his
supplier, the details of their FR007 and FR008
FR007 Low Expansion Frit
Na2O: 0.04
K2O : 0.53
MgO: 0.02
CaO : 4.66
B2O3: 25.15
Al2O3: 8.74
SiO2: 59.7
FR008 White Opaque Zircon Frit
0.419 Na2O 0.187 Al2O3 0.836 B2O3
0.010 K2O 3.956 SiO2
0.057 MgO 0.418 ZrO2
0.458 CaO
0.055 ZnO
I hope this will help those who begin composing their glazes via computer.
There is some interesting comparison work to be done on these figures.
I am finding that I can tweak existing glaze recipes by adding Low Expansion
or High Expansion Frits, to remedy crazing or crawling to the theoretically
correct coefficient of expansion.
David Hewitt's Glaze book is excellent for that. I recommend that UK potters
have it on their computer and add the above figures and those in Potclays
leaflet (available by post) and Select's Catalogue to the RM list in David's
program.
But the proof of the pudding is always in the kiln :-)
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
Steve Mills on thu 3 jul 03
For those who are interested; the corrupted frit analyses page on the
Bath Potters website has been reloaded, and should be OK now!
Steve
--
Steve Mills
Bath Potters Supplies Ltd
Unit 18, Fourth Avenue,
Westfield Trading Estate
Radstock, Bath. BA3 4XE
Tel: **44 (0)1761 411077
Fax: **44 (0)1761 414115
http://www.bathpotters.co.uk
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