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Using angle grinder to remove glaze from a kiln shelf?


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I have seen people are using an angle grinder to repair their kiln shelf. Is it safe? Could it be more likely that the shelf might break during the firing ? Normally if it's too serious I would just replace the shelf but lately I've been messing pretty badly, so I'm considering investing a bit of money in a good grinder. Is there any special disk recommended for this task?

 

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You're looking for a diamond cup wheel for your angle grinder.  Wear an n95 or n100 respirator, eye protection and gloves and do it outdoors.  It will clean large drips off in a matter of seconds.  You won't break the shelf, but you can go too deep and remove a chunk if you're not careful.

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One might find a masonry wheel would do the job ok.

I bought one like this (Ace brand) to round off porcelain tile (commercial floor grade) - takes it off with ease. The other grinding wheels we have - for metal - skate right over the porcelain. After making the shape, we went with finer and finer grit to get to a polished rounded edge. For your shelf, once the yuck is off, the kiln wash can smooth over the bit of rough.

Care, as Liam suggested, be paramount, for the grinder is one of the more dangerous power tools.

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Masonry wheels and diamond cups both work fine. The issue is not being able to remove the glaze- that's easy for the wheels. The difficulty is not gouging into your shelves. Work slowly and carefully. Just grind until get it smooth and level with the shelf, even if there's some glaze soaked into the shelf. Then coat it with kiln wash and fire it. The wash will soak into any remaining glaze and bind it. It may take an other application or two to get it fully soaked up.

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22 minutes ago, neilestrick said:

Masonry wheels and diamond cups both work fine. The issue is not being able to remove the glaze- that's easy for the wheels. The difficulty is not gouging into your shelves. Work slowly and carefully. Just grind until get it smooth and level with the shelf, even if there's some glaze soaked into the shelf. Then coat it with kiln wash and fire it. The wash will soak into any remaining glaze and bind it. It may take an other application or two to get it fully soaked up.

I just gouge the glaze out and fill with kiln wash.  I used to grind it level but where the glaze was would end up shrinking down and making a divot anyway.

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For years, I used a chisel and hammer on hard stuff, finished with a hand grinding stone made for kiln shelves. Slow, but worked. Now, I take off the hard stuff with the grinder, smooth with careful motions and then use a hand stone to finish. 

It will be interesting very soon, as I will have all new shelves, and kiln. 

 

best,

Pres

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42 minutes ago, fergusonjeff said:

I second the diamond cup wheel.  They are much more expensive than a masonry disk, but will remove glaze that masonry disks just seem to heat up.  I found a diamond cup wheel at harbor freight for under $30 and eventually replaced it with another cheap one from menards. 

There's some cheap ones on Amazon too.  They do cut through glaze way faster than a masonry disc.

Here's a video I made showing the process:

https://youtu.be/2SYuCtHEszc

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Loved the video Liam, but whenever I work with shelves either grinding or otherwise, I wear gloves. Back about 1985 I picked up a shelf after chiseling and hand grinding. Cut myself on a piece of glaze on the edge I hadn't noticed. Took a long time to heal and as it was in the palm of my hand, it hurt quite a bit when centering.

 

 

best,

Pres

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14 minutes ago, Pres said:

Loved the video Liam, but whenever I work with shelves either grinding or otherwise, I wear gloves. Back about 1985 I picked up a shelf after chiseling and hand grinding. Cut myself on a piece of glaze on the edge I hadn't noticed. Took a long time to heal and as it was in the palm of my hand, it hurt quite a bit when centering.

 

 

best,

Pres

I usually do, and I usually don't do it right there on the ground.  I also do mine wet and then hose them down afterwards, makes for an easy application of shelf wash

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Posted (edited)

I'm back! So could a cheap angle grinder with a diamond cup wheel work ? Or should I spend more money in the machine itself? They sell some really cheap ones (500W 115mm $15) out there but I'm not sure if this would be enough. 

 

How about this wheel?

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Edited by thiamant
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3 hours ago, thiamant said:

I'm back! So could a cheap angle grinder with a diamond cup wheel work ? Or should I spend more money in the machine itself? They sell some really cheap ones (500W 115mm $15) out there but I'm not sure if this would be enough. 

Get a cheap angle grinder, as the dust from the kiln wash will eat up the motor at some point.

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Thiamant,

A cheap grinder is fine.  I have about 5 and most were under $20.  The wheel you show is for cutting bricks, not grinding surfaces.  Look for one more like this:

https://www.ediamondtools.com/products/premium-turbo-diamond-cup-wheels?variant=11941428932&gclid=CjwKCAjw9MuCBhBUEiwAbDZ-7qLxkyvo0l-3rMlytTa0pH5Vy9oOgZCtsJfOoLImBx47F3tZP_-VlhoC4SMQAvD_BwE

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  • 5 months later...

Hi all,

I'm jumping in here because I've had an embarrassingly newbie meltdown... cone 06 clay body in a cone 6 glaze fire...  :huh:

Anyway... I get that I could use an angle grinder to remove the puddle but I also wouldn't mind that edge of the shelf.

If I could cut the shelf,  what tool would you all suggest I cut it with?

Thanks,  Andryea

 

 

melted blob.jpeg

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