Grinding m,arks

[Alisonlowery]

 
I get white grinder marks on my pieces which don't melt out and spoil them. I use a fine grinder bit, keep the water as clean as possible and use grinder fluid. Is there anything I am doing wrong? Should I keep to one type of glass per session, eg transparent separate from opal? Anybody else have this problem? Alison L.

[julieHB]

Hi Alison, you don't say anything about firepolishing - you do firepolish after grinding, don't you?  If you don't, you need to use a lapidary polishing machine to be able to polish smooth  and shiny.

If you do firepolish and still have the misty grayish mark along the outside you are probably ramping too quickly.  I was tearing my hair out before I figured this one out!  You need to ramp very slowly up until you reach about 500 deg C, then you can ramp quickly up to about 100 deg C less than your full fusing temp (on my paragon sc2 that means approx. 720 deg C for Bullseye glass), and soak it there for some time, depending on glass thickness.  If you want the edges to be rounded you then bring it up to fusing temperature before cooling down.

Clear glass seems to need longer time than dark glasses. I cannot remember the schedule I have found to work as my kiln is on at the moment (and I cannot remember what it is), but if you are interested in knowing, just pm me and I'll send it to you.

[Zeldazog]

Oh, thanks for that tip, Julie, that's useful - I havne't had an issue (yet) with this (apart from not taking a fire polish high enough to round off as much as I wanted) - as the kiln was new, I have tended to ramp up on the conservative side anyway, but its worth knowing about this for future reference

[Alisonlowery]

Hi,
I tried to firemy stuff in the skutt hotstart on the slowest full fuse cycle, and I definitely found that it helped, although the marks didn't completely disappear.I will try your suggested schedule later. Thanks, Alison L

[Zeldazog]

Hi Alison

Assuming you used the Hotstart's standard glass programme, they are actually set for Spectrum System 96 glasses - according to Dennis Brady of Wetcanvas, Bullseye needs to be about 25 degrees (fanrenheit that is, I think) - higher than Spectrum

So, if you're using Bullseye, that might explain why the full fuse still didnt' fully take out the grinding marks.

[Dennis Brady]

Hi Alison

Assuming you used the Hotstart's standard glass programme, they are actually set for Spectrum System 96 glasses - according to Dennis Brady of Wetcanvas, Bullseye needs to be about 25 degrees (fanrenheit that is, I think) - higher than Spectrum

So, if you're using Bullseye, that might explain why the full fuse still didnt' fully take out the grinding marks.

Yup.

If you're using a Spectrum schedule to fire Bullseye, increase all temperatures 25 deg F.
If you're firing architectural or float, increase by 50 deg.

[Alisonlowery]

Hi to all.
Yes, thanks for that information. That's probably why the tack fuse is weak too.
Alison.

[welchy]

When you do your final grind make sure that the water is clean in your grinder (no sludge being pulled up from underneath) also fine grind each peice so that all marks from the rough grind are completely gone.
Then as you finish each piece drop it into a bowl of dish washing liquid (I use fairy liquid) leave to soak for a couple of hours then rinse - keep the liquid as you can re-use it over and over.
Make sure that your cabs are completely rinsed of any soap trace and then pat them dry using kitchen roll and fire as normal, your finished cabs will be super crystal clear I promise 

[Alisonlowery]

Thanks, I think a better water washing system would help too. Alison

[Intelekt]

 

Hi Alison, you don't say anything about firepolishing - you do firepolish after grinding, don't you?  If you don't, you need to use a lapidary polishing machine to be able to polish smooth  and shiny.

If you do firepolish and still have the misty grayish mark along the outside you are probably ramping too quickly.  I was tearing my hair out before I figured this one out!  You need to ramp very slowly up until you reach about 500 deg C, then you can ramp quickly up to about 100 deg C less than your full fusing temp (on my paragon sc2 that means approx. 720 deg C for Bullseye glass), and soak it there for some time, depending on glass thickness.  If you want the edges to be rounded you then bring it up to fusing temperature before cooling down.

Clear glass seems to need longer time than dark glasses. I cannot remember the schedule I have found to work as my kiln is on at the moment (and I cannot remember what it is), but if you are interested in knowing, just pm me and I'll send it to you.

Hi, I'm Adrian and this is my first post here, I know this topic is old but being new to fusing I encountered this same problem yesterday. I did a search and found this 

It's very interesting that it is the fusing schedule that has to be tweaked to remove these marks.

Has anyone got a kiln schedule for removing grinder marks?
I am very interested in knowing yours JulieHB if you still have it after all this time 
I have a Paragon SC2 kiln so has anyone got a schedule for this kiln?

Many thanks
Adrian

[Trudi]

I found that running them on a firepolish schedule got rid of them, but you need to use shelf primer and not kiln paper!