Tiny Pockmarks

[lbailey]

Occasionally I get these very tiny pockmarks in a finished piece, in this case a 10" square plate. There is no kiln debris or other material in these tiny round depressions, and this particular piece was fired in a kiln with a fiber lid. I frequently vacuum all the exposed firebrick in both my kilns and make sure my shelves and furniture are clean.

Tried to take a picture to post but these depressions are so small I can't really pick them up in a photo (at least from my iphone).

This 10" plate includes two sections of Egyptian Blue above and below a row of rod box melt slices. There are about very small 4-6 pockmarks on each of the blue sections and I can see a few in the center section of the slices. They aren't really noticeable unless you carefully inspect the piece but just not a great result.

Any ideas or suggestions? I don't want this be become the normal level of quality.......

Thanks

[Marty]

Bullseye, I presume? If you look at Klaus Moje's stuff close up you'll find the same pits.
Don't worry, be happy.

[lbailey]

Yep, all Bullseye. Just so annoying to see these after you work hard to keep everything clean.......

[Laurie Spray]

Sprinkle some powder before firing......works well for me!

[Kathy K]

Laurie,
Is the idea to always sprinkle powder (do you mean clear?) and the little pockmarks won't show up.
thanks,
Kathy

[Laurie Spray]

When I read it quickly yesterday I thought the zits were on the pattern bars…..but if they are all over it makes me wonder what your firing schedule is?

[lbailey]

Not all over, maybe 8-10 very small, shallow marks on a 10" square plate. This was not made with pattern bars, used a 2 rod flow box and book matched slices from the bar. The marks are very small and don't appear to be from bubbles or debris. I'd attach a pic but no way to show the little marks. Besides, I can't find the instructions to post a pic (and I used to have some tech skills...... )

The plate was fused, fire polished and slumped:

Fuse:
300 dph to 1100 F hold for 10 min
200 dph to 1250 F hold for 1 hr
AFAP to 1490 F hold for 30 min
AFAP to 900 F hold for 2 hr
100 dph to 700 F no hold

Longer holds at 1250 and 1490 to fully fuse rod bar slices

Some slight devit so SBed both sides with 120 grit and polished with 220 and 400 hand pads

Fire Polish
200 dph to 1100 F hold for 10
200 dph to 1250 F hold for 30
AFAP to 1350 hold for 10
AFAP to 900 hold for 1.5 hr
100 dph to 700 no hold


Slump
150 dph to 1100 hold for 10
AFAP to 900 hold for 1.5 hr
100 to 700 no hold

[lbailey]

Picture

[Morganica]

Where are the marks?

[lbailey]

Very small, can't pick them up with a camera (my phone, I guess a better photographer could).

Mostly in the blue top and bottom sections, I'll work on closeups and see if I can post a pic. But they are very small, nothing in them, don't look like a bubble pop.

I wonder if they are caused from some contamination from my towels, sink or......?

[Marty]

It's not you or your schedule; they're tiny bubbles in the glass, Bullseye put them there. I used to grind to get them out but would just expose a new set.
If you try Laurie's powder solution you risk discoloration from a different color lot.
Get over it, or try another glass.

[lbailey]

Thanks Marty, I wondered if that was it, or if I could do something differently to avoid them.

I have experimented with clear powder and also saw a slight color shift, but I suspect that if done correctly for a single piece it would work Ok. But I think I'll just get over it for now.....

Thanks guys