Sandblast prints, stack and fire?

Catharine Newell · Post by **Catharine Newell** » Wed Apr 30, 2003 9:45 am

I have been tackfusing two prefired 24x17x1/4" panels, adding frit detail. I will stack them, add a third, and fuse all three into one 3/4" panel. The middle layer shows fingerprints on the bottom surface (oh, careless me!), which will be quite obvious over the red background behind the figure.

Two questions: 1. Is a light sandblasting on the underside of the middle layer the way to go here to remove the prints? 2. Will the sandblasted surface leave any unexpected effects when the panels are stacked and brought to a full fuse? Common sense tells me no, but...

Lots of hours into this,
Catharine

Brock · Post by **Brock** » Wed Apr 30, 2003 10:02 am

It should work Catharine, with a light blast. Do we have to enter the Silicon Carbide vs Aluminum Oxide debate here? I vote for the latter. Is it possible to add any detail to the affected area?

Good luck,

Brock

PS More slides?

Catharine Newell · Post by **Catharine Newell** » Wed Apr 30, 2003 10:07 am

Hey Brock!

I'm looking forward to seeing you sometime in the next couple of weeks - it's been awhile....

It's not possible to add detail to these areas... strictly solid background. Wouldn't cha know?

Going to the photographer on Tuesday for all new work. You can peruse and select new slides when you get to Seattle - how about that? I can ply you with slides!

Catharine

Brock · Post by **Brock** » Wed Apr 30, 2003 10:10 am

Looking forward to it. Consider me plied. Brock

Phil Hoppes · Post by **Phil Hoppes** » Wed Apr 30, 2003 10:17 am

Brock,

I never heard the end of this debate and was curious. My blaster is loaded with SiC which for surface carving and top irid blast is fine. I got an order for the Celtic pattern sushi I did in your class which will be an embedded sandwich a-la your style. I was thinking of doing a test case for myself and just make two. I'll blast one with mine and use Jackie's for the second and see if I can see any difference.

Just curious,

Phil

Tony Smith · Post by **Tony Smith** » Wed Apr 30, 2003 10:30 am

The electon microscope images and analysis from Nikki showed that the silicon carbide is indeed a more aggressive abrasive, which we knew, and creates microscopic fractures in the glass that are deeper than those created by the aluminum oxide. It also shows that even a smooth-looking, firepolished surface that had been blasted with silicon carbide has entrapped, microscopic air bubbles under the surface.

Dr. Steve is putting together a summary page.

Tony

Brock · Post by **Brock** » Wed Apr 30, 2003 10:31 am

I don't have a definitive answer either, but the overwhelming preponderance of anecdotal evidence suggests that more problems
occur with SiC. I am positive it is NOT a cleaning issue.

I agree it is not a problem with surface blasting, which leads me to surmise that it may have something to do with the way the grit attacks the glass, and the effects when they are fused together. I think Steve mentioned this earlier in the original thread.

I never have problems with AlOx, and have had with SiC. I have also had successes with SiC. The responses to the recent thread on this has prompted me to make an entirely different Pilchuck Auction piece. It is just not worth the risk, with the amount of work in these pieces.

More results would be welcome, but I think I'll stick with AlOx.

Brock

Jackie Beckman · Post by **Jackie Beckman** » Wed Apr 30, 2003 10:41 am

ahh Brock, I was just wondering about that Pilchuck piece of yours. You must have been reading my mind. What did you end up doing?

Doug and I were just talking about abrasive choices and their various uses. After our conversation I am about to switch over to SiC 220 rather than my Al Oxide, so Phil, I'll wait until you conduct your tests over here. Hey, wait a minute. What grit SiC do you have Phil? If you have 220 in there, let me know - I may need you to do a little test for me. Otherwise, how do you feel about supervising my switch over from the Al oxide? I don't know how to tell when it's cleaned out enough to put in the SiC - do you?

Good luck today with your gallery!! Everyone send good vibes Phil's way today!!! See you tomorrow, when your famous.

Brock · Post by **Brock** » Wed Apr 30, 2003 10:47 am

I haven't done it yet, but I'm going to make a different piece. The blanks I have sandblasted with SiC, I'll finish eventually, to see what happens.

Ditto to Phil, good luck.

Phil Hoppes · Post by **Phil Hoppes** » Wed Apr 30, 2003 10:48 am

Hi Jackie,

My blaster is loaded with 120 SiC. I'd heard the 220 is so fine it just goes everywhere and has a tendency to cloud the chamber more. I'm sure Tony is far better versed than me on this. I should be doing the piece next week so I'll probably want to snag a blast at that time. Another lunch you think?

Thanks for the good vibes. I'll see the director at noon. Maybe a Champagne Brunch tomorrow huh?

Cheers,

Phil

Jackie Beckman · Post by **Jackie Beckman** » Wed Apr 30, 2003 10:56 am

Phil Hoppes wrote:Hi Jackie,

My blaster is loaded with 120 SiC. I'd heard the 220 is so fine it just goes everywhere and has a tendency to cloud the chamber more. I'm sure Tony is far better versed than me on this. I should be doing the piece next week so I'll probably want to snag a blast at that time. Another lunch you think?

Thanks for the good vibes. I'll see the director at noon. Maybe a Champagne Brunch tomorrow huh?

Cheers,

Phil

Well, the problem I'm having is that it wasn't just anyone who suggested the SiC, it was DOUG so I may need to switch!

I actually would like to try it first though. You know some of my detail work on the face of my pieces is just little fine frit dots, and I'd hate to blast them off!! I'll send him a small piece to test, as he suggested I think, before I make the switch. So you have plenty of time to blast whatever you want over here. Another excuse for lunch out is always good!

Don't sell yourself short today - the work you're doing is beautiful - make sure he knows that!

Take care,
J

Tony Smith · Post by **Tony Smith** » Wed Apr 30, 2003 11:50 am

The 220 grit is pretty fine and tends to create a cloud in the cabinet. I've found that the 180 grit is an acceptable compromise. But even I'm considering setting up one cabinet with Al2O3 to evaluate the differences. I'm sure the shocks will start me twitching though :badgrin:

Tony

Brian and Jenny Blanthorn · Wed Apr 30, 2003 3:29 pm

Tony Smith wrote:The 220 grit is pretty fine and tends to create a cloud in the cabinet. I've found that the 180 grit is an acceptable compromise. But even I'm considering setting up one cabinet with Al2O3 to evaluate the differences. I'm sure the shocks will start me twitching though :badgrin:

Tony

280 SCi but I do have real good extraction so I remove the dust but not the grit

I would expect the light sandblasting 2 leave a light haze but if u looking through it might B nice ( they R actually small bubbles )

But if U wanna cheet flux should hide the sandblasting nealy entirely depending on heat

U might try rubbing the area with pumace / fine grit instead

Steve Immerman · Post by **Steve Immerman** » Wed Apr 30, 2003 3:41 pm

Hi. I was going to wait to post this, but since we're back in the middle of this discussion again, I'll show you what I have so far. Nikki is making a few more photos for me, but the following web page has the info so far. I'd be interested in everyone's opinion on this.

My theory is that there is something different between how SiC and Al2O3 interact with glass during the blasting. Something physical or chemical. Surfaces blasted with SiC don't seem to "recover" back to a normal smooth surface after firepolishing, even up to full fuse temps.

Most of the time, particularly with black glass, the surfaces when blasted and firepolished look pretty good with both abrasives. But, I found with some colors of glass, the SiC blasted surfaces never came back to the way I wanted them to.

When I tried Brock's double irid technique with SiC, a very noticeable haze was present - and I think that the process of laying clear over the underlying black glass makes the surface imperfections/bubbles more noticeable because of the optics of the situation.

Why this happens, I have no idea. Maybe some of our engineers, chemists, or geologists can come up with a theory.

So, Catherine, I'd think twice before blasting the back with SiC, but go for it if you have Al2O3.

Here is the link with the photos so far:

http://www.clearwaterglass.com/SandblasterTest.htm

Steve

Tony Smith · Post by **Tony Smith** » Wed Apr 30, 2003 4:43 pm

Steve,

It might be worthwhile to send Nikki samples of the SiC and Al2O3 to get micrographs taken of the abrasive particles. It might shed some light on the problem.

Tony

Steve Immerman · Post by **Steve Immerman** » Wed Apr 30, 2003 4:46 pm

Tony,

I agree. I also asked her to see if she can get higher power views of the sandblasted, but not firepolished, surfaces to see if there is any obvious difference. With the power we have, I don't see much difference.

Steve

Victoria Nelson · Post by **Victoria Nelson** » Wed Apr 30, 2003 5:09 pm

Two questions: 1. Is a light sandblasting on the underside of the middle layer the way to go here to remove the prints? 2. Will the sandblasted surface leave any unexpected effects when the panels are stacked and brought to a full fuse? Common sense tells me no, but...

Q1: If it removes kilnwash it should remove fingerprint!
Q2:
I sandblasted the back of a panel using Alum Ox to remove some kilnwash that stuck . I did blaast all the panels just incase something would show, at least it would be the same in all panels!?!
I then fused a backing colour to very clean glass. Only one of the 4 panels showed a slight imperfection.
The imperfection.... A very small bubble that was a little hazy where the top and bottom layer didn't make complete contact. It was ok considering it was an underwater scene and bubble very tiny. The top layer was clear with different transparent and opal glass used to create a scene with the backing transparent.

Brian and Jenny Blanthorn · Thu May 01, 2003 4:13 am

Steve Immerman wrote:Hi. I was going to wait to post this, but since we're back in the middle of this discussion again, I'll show you what I have so far. Nikki is making a few more photos for me, but the following web page has the info so far. I'd be interested in everyone's opinion on this.

My theory is that there is something different between how SiC and Al2O3 interact with glass during the blasting. Something physical or chemical. Surfaces blasted with SiC don't seem to "recover" back to a normal smooth surface after firepolishing, even up to full fuse temps.

Most of the time, particularly with black glass, the surfaces when blasted and firepolished look pretty good with both abrasives. But, I found with some colors of glass, the SiC blasted surfaces never came back to the way I wanted them to.

When I tried Brock's double irid technique with SiC, a very noticeable haze was present - and I think that the process of laying clear over the underlying black glass makes the surface imperfections/bubbles more noticeable because of the optics of the situation.

Why this happens, I have no idea. Maybe some of our engineers, chemists, or geologists can come up with a theory.

So, Catherine, I'd think twice before blasting the back with SiC, but go for it if you have Al2O3.

Here is the link with the photos so far:

http://www.clearwaterglass.com/SandblasterTest.htm

Steve

SCi is a lot harder close 2 diomond

The cristal structure is sharper n on breaking gives sharp fractures

I would expect it 2 give the glass deep fractures n a very rough surface

I think with the irid its doing weird stuff like combining with it or shoving it deeper in2 the glass

I dont know about alumina but it is a lot softer

Some forms of it R oblong rather than pointed

At the end of the day its what actualy works

A lot of whot I do is knowledge / guessing / what actually works

But an aufle lot is awairness of weird results / failures

Its in the failures where success lies

Fail n Succeed tm

Steve Immerman · Post by **Steve Immerman** » Thu Jun 19, 2003 8:59 am

Catharine Newell wrote:I have been tackfusing two prefired 24x17x1/4" panels, adding frit detail. I will stack them, add a third, and fuse all three into one 3/4" panel. The middle layer shows fingerprints on the bottom surface (oh, careless me!), which will be quite obvious over the red background behind the figure.

Two questions: 1. Is a light sandblasting on the underside of the middle layer the way to go here to remove the prints? 2. Will the sandblasted surface leave any unexpected effects when the panels are stacked and brought to a full fuse? Common sense tells me no, but...

Lots of hours into this,
Catharine

Catherine,

What ever happened with this piece? Did you sandblast? Did it fix the problem?

Steve

dee · Post by **dee** » Thu Jun 19, 2003 9:28 am

Phil Hoppes wrote:Hi Jackie,

My blaster is loaded with 120 SiC. I'd heard the 220 is so fine it just goes everywhere and has a tendency to cloud the chamber more. I'm sure Tony is far better versed than me on this. I should be doing the piece next week so I'll probably want to snag a blast at that time. Another lunch you think?

Thanks for the good vibes. I'll see the director at noon. Maybe a Champagne Brunch tomorrow huh?

Cheers,

Phil

i use 220 SiC with a siphon feed system for surface blasting, yes it does cloud the chamber and merrily fly around, but i also run a vacuum to keep the clouding to a minimum - since this is the final stage for these pieces i don't have to worry about problems later back in the kiln...

WarmGlass.com

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