Tips for Removing Glaze from Advancer® Shelves

We are often asked, “What is the best way to remove glaze from Advancer® kiln shelves?” The general answer to this question, although admittedly vague, is to use the least aggressive method possible. It is important to keep in mind that Advancer shelves have a porosity of less that 1% compared to traditional pressed silicon carbide and cordierite with porosities in excess of 15%. The effect of this is that when glaze runs, drips or volatilizes onto an Advancer shelf, it cannot penetrate the shelf. Unlike cordierite or pressed silicon carbide, glaze does not sink into and beneath the shelf surface, and does not leave a divot in the shelf surface after removal.

While this does not mean that the Advancer surface is like a non-stick frying pan, it does mean that removal will be considerably faster and easier. Glaze and heavily fluxed porcelain clay bodies can still fuse and grip onto the oxide layer present on the shelf surface. However the non-porous surface does make glaze considerably easier to remove than glaze that has infused beneath the surface as with other types of shelves.

Round, globular drips or runs are easily removed by using a paint scraper or putty knife with a rigid, stiff metal blade and normally do not require grinding of any sort. Larger raised areas can usually be removed by blade scraping if done soon after shelves are removed from the kiln.

In the event of a very fluid run or glaze volatilization that covers a larger shelf area of an inch or more, a combination of scraping and grinding will be required. Keep in mind that even in these instances, glaze is still sitting on top of the shelf surface so it is not required or recommended to grind beneath the shelf surface. Because Advancer is very hard, it is difficult to do this anyway.

Keeping in mind that it is still preferable to use the least aggressive method possible, you may wish to start with a 60 or 80 grit, alumina oxide sand paper or emery cloth. Silicon carbide rubbing stones, knife sharpening stones or even fire brick posts may also be used for this purpose. Surface scratching and dulling are inevitable once you use any of these methods. This not detrimental to long term shelf performance, but may make ongoing glaze removal more time consuming.

Obviously this is not going to be practical if glaze thickness on the shelf is over a 1/16”. In this case you will need to grind with something like a masonry or ceramic tile grinding wheel or similar flap-disc type wheel mounted on an angle grinder or Dremel® tool.

If you are spending a lot of time removing glaze from shelves after each firing, you should consider using a high alumina wash on the shelf. This will make shelf maintenance easier in the long run. Glazes that consistently volatilize or spray onto your shelves will build up on the shelf making subsequent removal more difficult if left unchecked and will also cause pots to glaze and stick onto the shelf. Ultimately these types of glazes should only be used on kiln washed shelves.

For routine maintenance and removal of occasional glaze drips and other kiln debris removal, we will soon be introducing a hand tool made of the same material as our GlazeEraser® wheel head grinding disk. Check it out soon at www.GlazeEraser.com.

1 comment (Add your own)

1. Lisa loves pottery wrote:
The glaze eraser looks really cool! What a brilliant idea. Can't wait to get one!

Thu, September 26, 2013 @ 4:16 PM

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