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High Bridge Pottery

Member Since 19 Feb 2013
Offline Last Active Today, 02:11 PM

#126593 Ian Currie Test Tiles Forums?

Posted by High Bridge Pottery on 12 May 2017 - 09:37 AM

The way my equation should work is:


You take out the first 4ml (could be any known amount) out each cup for two tiles and weigh the liquid glaze left in a cup. Put that through the equation and get total dry glaze in the cup. Mix up the 80ml of 40 x 1% oxide and add 2ml to each cup.


Run another grid, put the new weight of liquid glaze and ml through and mix up a new solution of 80ml to add into cups. I think you should take off any extra oxide you have already added to give a better estimate of total dry base glaze.


This way I think as long as you take out measured amounts each time you can quickly calculate dry weight.

#126377 Looking To Start Mixing My Own Glazes

Posted by High Bridge Pottery on 08 May 2017 - 10:02 AM

If they had any magical ingredients their marketing team would be all over it. They have the same rocks/periodic table we do with clever people behind them.

#125779 Qotw: The Power Grid Has Gone Down In Your Area A...

Posted by High Bridge Pottery on 25 April 2017 - 03:00 PM

I would go to the National Grid and fire everybody at the top.

#125764 Recommend Me: A Glaze Material Book For Foundation Principles.

Posted by High Bridge Pottery on 25 April 2017 - 09:42 AM

I have been thinking about the grid after watching the video you posted with L shaped tiles. I have come round to the idea that only flat tiles are not the best way to do it. I am thinking if you could extrude L shaped tiles and have them in rows you can get both flat and vertical surfaces in the grid. Can't remember the guys name now but I liked the test tiles.


I think the grid method is the quickest way to get the most results. If I compare it to a line blend, you mix up 2 glazes, blend 5 times and get 5 results. The grid you mix up 4 glazes, blend 35 times and get 35 results. I think for a line blend it would be 15min for 5 results and a grid 60min for 35 results. They are vague estimates but that's 3 min a test for the line blend and 1.7min for the tile.


Sometimes the most basic tests of incremental additions have their place but I always think why not squeeze out the extra tests as I am measuring out glaze anyway. You get the test of 'what happens if I go from A to B' also with a C and D thrown in for half the price. 


An example might be using Campana Clear from JohnB 

Spodumene    11
Silica       20
Wollastonite 20
Kaolin       20
Frit 3134    21
Zinc Ox       8 

Let's see what happens with different zinc amounts and get glaze A no zinc, glaze B 15% zinc. Instead of doing a line blend I would think maybe take out all the spodumene and try that too. Now you get glaze C no zinc or spodumene, glaze A has 15% zinc, glaze D has 20% spodumene and B has both. The original glaze is probably somewhere in the middle of the tile with a whole mix of other glazes for little more effort. Maybe you also know the clear works well with 0.25% cobalt carb so after running the first tile you add cobalt to each glaze and run again to see how the changes may work with colour. Just need to make sure you mix enough of the corner glazes and know the total volume you removed.


These would be my thoughts on running tests with a glaze, there is no intended end point, just taking stuff out and putting too much back in to see what happens, the currie test only does this with silica and kaolin but pick whatever you like.


I couldn't put my finger on any knowledge I have gained but I have plenty of different surfaces to look at. I think you know most you need to about the oxides we are using but it's not until you melt them together you actually find out what happens. A lot of the time you end up with nothing much exciting but you can always go back to the tile to see the answer to your question. I find you need to ask the questions and line blends, trialax and currie grids are just quicker ways to more answers.


I think this is still my favourite tile. It's a 50/50 mix of whiting and soda feldspar for the flux with the typical currie varying kaolin and silica. Only 4 ingredients but so many different surfaces and textures.


#125725 Kiln Conversion Updraft Downdraft Chimney?

Posted by High Bridge Pottery on 24 April 2017 - 07:38 AM

It was a nice day yesterday so I decided to fire the kiln. First change was to take down the chimney again to the height of the kiln. The tube was precarious and I don't think it was changing much with the forced air burner.


I need some kind of safety and pilot on this burner, it's too fast below 400c and keeps going out with a bang. After 400c it is very good but low end is bad. Not sure how to do that yet or have the money to. Need to stand by for the first 2 hours and hope the pots can brave 200c an hour.


The flame out the kiln was a brilliant blue with green tips. Hard to get a good photograph of it. The reduction across the kiln was good on the burner side and bad to oxidised on the flue side. I think this may be partly down to shelves too close to the wall on that side.


Is it also something to do with my flame colour? Do I really need to be getting some sooty yellows? I need an oxygen probe instead of talking flames.








I also need a better thermocouple, this one is way off and hits cone10 at 1140. It was only half a cone difference top to bottom.


Another interesting note, in my body reduction which I hope was 900c~ the brick I used to close the chimney built up a yellow tinge also smelt very eggy. Thinking some of my glaze materials might have a lot of sulphur. Just a thought. Maybe the clay.

#125720 New Kiln Burners

Posted by High Bridge Pottery on 24 April 2017 - 04:42 AM

So, I was firing the gas kiln last night to cone10 and didn't even reach 1psi on my regulator. Thought I could share my figures.


The orifice I am 99% sure was 1.5mm or about 1/16th which olsen tells me has a fuction 10,492.70 and 1psi has the function 4.2661. If you multiply them both together you get the BTU which gives me 44-45k BTU max for a size of slightly over 6 cubic foot.


I think I am looking at 6-8k btu/cf for my gas kiln conversion even with thin electric kiln walls.

#125719 Recommend Me: A Glaze Material Book For Foundation Principles.

Posted by High Bridge Pottery on 24 April 2017 - 03:57 AM

I love reading up on chemistry but you can always melt some rocks and see what happens, that's the best way to do it.

#125505 Can't Throw, Can Extrude

Posted by High Bridge Pottery on 18 April 2017 - 04:07 PM

I am jealous  :lol: They look great

#125338 Pottery Knowledge Quiz Of The Week(Pkqw): Week 2

Posted by High Bridge Pottery on 13 April 2017 - 01:09 PM

Pres what was the problem with getting an image in the post?




#125335 New Kiln Burners

Posted by High Bridge Pottery on 13 April 2017 - 12:25 PM

General guess is 10,000btu/cf so 200,000 seems good.


Chimney sounds a good size too. That's worked out as 3x downward pull + 1/3 horizontal pull.


You can make a good quality forced air burner for half the price of a 'new' venturi burner

#125332 Iron In Glaze? Absolute Beginner's Questions

Posted by High Bridge Pottery on 13 April 2017 - 12:04 PM

Not sure if your kiln has a programmer but this talks about firing kilns


and what happens during the firing


a list of major oxides used in glaze


some more about oxides



It will take you twice as long as half the length it takes you  :ph34r:

#125178 Us To Uk Frit Substitution Chart?

Posted by High Bridge Pottery on 10 April 2017 - 09:13 AM

This is the best I can do to match chemistry, doesn't mean they will melt exactly the same as the right frit but could be a start. Hard to get enough sodium in and always too much alumina or calcium. They use a lot of soda ash while making frits I think. Don't know how usable it is for a glaze material as it's soluble. 3110 was pretty much impossible to replicate.



#124953 Making Glazes

Posted by High Bridge Pottery on 06 April 2017 - 04:06 PM

There really should be a difference in weight. I don't think clay should weigh anything like silica or frits by volume.


The problem with scoops is they are inaccurate, If the weights were right and you retotaled the oz values into 100 then you could probably in theory work out what you need to add. That guessed recipe might not even match to what you actually scooped in. 


I worked out from your weights you have double the rutiile in the recipe or 195%

#124743 Fast Motion Booth Setup

Posted by High Bridge Pottery on 03 April 2017 - 02:40 PM

You don't need to do anything more than past the vimeo link into your post. Forum seems to do the rest. If that doesn't take you can use the media tags, or video tags.


Does the same thing.

I tried to add a size for the video so [media=1260,720]URL[/media] but that wouldn't work.

  • GEP likes this

#124675 Looking To Start Mixing My Own Glazes

Posted by High Bridge Pottery on 02 April 2017 - 08:21 AM

I generally start with 2/3 the weight of water. So if I am making a 5kg batch of glaze I will chuck 3-3.5 jugs (1000ml) of water in the bucket first, add dry and mix up then measure SG the next day and add water as needed.


I find 2/3 weight will get you to about a custard consistency