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ayjay

Member Since 05 Nov 2011
Offline Last Active Yesterday, 05:08 PM
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Posts I've Made

In Topic: Handles Make/break Your Pots

Yesterday, 01:34 PM


Vince Pitelka has a quite thorough article on side handles.

http://iweb.tntech.e...ing Vessels.htm

I'm happy enough with my handles, (usually rolled and then pulled some), they work, they're comfortable , they don't fall off. :)

 

I'm not too keen on rules of any sort and so I was interested to read in the linked article that some handle styles were now out of fashion, how does that square with having all these rules for handles?

 

Rules is rules, I'll follow them when I have to:  fashion is something else entirely, (which passes me by in everything).


In Topic: Alternatives To Wax Resist For Bottom Of Pots (Floor Wax)?

18 October 2014 - 02:11 AM

I've recently taken to using PVA glue mixed 50/50 with water as a resist on large areas (like bottoms of large platters) I was running short of wax and wanted to try something different to save a trip to the ceramic shop.

 

It works well, and any overspray of glaze cleans off it easier than it does off of wax resist.

 

PVA glue is a white wood glue used by carpenters, (I  have a never ending supply) , i believe it's called Elmers on the other side of the pond.

 

 


In Topic: Brushing Glaze: How Long Between Coats?

12 October 2014 - 02:23 AM

For  their glazes designed to be brushed on, Amoco recommend a *soft fan brush*:  having tried various types of brush I can only agree with them.

 

It's important to remember you are not painting a door, you are transferring glaze to a pot by brush.

 

These  are similar to what I use.

 

 


In Topic: Blistering

08 October 2014 - 04:36 PM

or it cooled too quickly and the molten glaze froze while bubbling rather than settle down first.

Sometimes if you run a very light weight load in the kiln it will cool too quickly since it does not have the thermal mass to cool slowly.

Was it a light load?

 

It was a fairly light load, there were another two large (but shallow) items (one apiece on a shelf - and no room for anything else) and the highest shelf (at the centre of the kiln's height) was full of smaller items.  The kiln temperature drops at about 100°C per hour.

 

I know the theory of the *frozen* bubbles, but these look worse than that, there doesn't appear (to me) to be anything there to heal over with a slower cool.


In Topic: Blistering

08 October 2014 - 04:23 PM

There are several possible reason for the blistering:

 

1. The Frit you used is not the same as Gerstley Borate, and therefore is not going to react the same. The only direct substitute for Gerstley is something made specifically to be a substitute, like Gillespie Borate or Laguna Borate.

2. Glaze too thick, although I doubt it

3. Glaze doesn't like the other glazes that are under it.

4. Ash glazes are quite unstable. It could be that you need to adjust the glaze. I would start by adding small amount of silica and/or alumina. Too much and you'll lose the rivulets, but you may be able to find a balance. All ash is different, so just because you used washed pine ash doesn't mean the glaze will work. The degree to which you washed it and the makeup of the wood used to make the ash will all affect the melt. Personally, I would revise the recipe to a fake ash glaze to avoid the inconsistency of real ash.

5. Kiln temp was not correct.

1)  I use it regularly in place of both GB and FF3134, it's not been a problem before, although I appreciate that the chemistry is different.

 

2) This is still my best guess.

 

3) There's only a light (airbrushed coat) of SCM under the ash glaze, and the same is on the pic later in this post, but a much lighter coat of the ash glaze.

 

4)I'll give it a try - would 2 or 3 tests at 5% increments be about right? Should I reduce the ash by similar amounts or is that too much of a change?   Silica is straightforward enough, what's  best for the alumina? I already have  Alumina Hydrate, China Clay and Ball Clay - is there a best option?

 

5) I'm 100% confident the kiln temp was correct - no cones in this firing but I do use them regularly and they have always been spot on.

 

One thing I'd like to understand  is the actual process of when the bubbles were formed, the rivulets going down to the centre are as smooth as a babies bum, did they run before the rest blistered or after?  

 

The rivulet effect has all but disappeared from the top edge of the bowl - does this indicate that I should be firing this cooler or adjusting the melting temperature upwards somehow?

 

This goblet has the same SCM as a base and another glaze over that and then a light coat of the ash glaze, just brushed on under the rim, there's no hint of any blistering.

 

Ash_goblet_zpsb11be047.jpg