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Food Stains on Glass

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Food Stains on Glass

Postby eablitz » Mon Dec 31, 2012 6:51 am

I have a discouraging problem. Twice I have had food placed on fused glass platters leave seemingly permanent marks. The first was on Powder Blue Opalescent. Sushi was set out at a party for a couple of hours. Slight circular ghosts were left behind on the glass. I wrote it off to the vinegar in the rice, or the nori or wasabi having an unusual effect and put the plate away. This time it is with French Vanilla Opalescent glass. Squares of noodle pudding have left a grid on the platter. It is not obvious unless light strikes the plate just right but neither of these platters can ever be displayed. I have tried isopropyl alcohol, acetone, mineral oil, CLR, vinegar, and plain old soap and water and nothing makes a difference. Any suggestions? Has anyone else had a similar problem?

My husband, with a PhD in Chemistry will try Nitric Acid in a lab setting but it is kind of ridiculous. How do I sell platters labeled "food safe, hand-wash, and by the way don't actually use?"
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Re: Food Stains on Glass

Postby Stephen Richard » Tue Jan 01, 2013 9:13 am

What is it about these that means they cannot go into the dishwasher?
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Re: Food Stains on Glass

Postby eablitz » Tue Jan 01, 2013 4:32 pm

I put mine in the dishwasher but To be safe I wouldn't want to reccomend it to those that purchase my work. Over time some dishwashers or detergents have left glass items old and etched looking. However, the dishwasher did not remove the food stains.
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Re: Food Stains on Glass

Postby marykaynitchie » Wed Jan 02, 2013 10:44 am

How aggravating for you! I serve food on my fire-polished Bullseye plates and have not experienced this. Most of the food I have served on my plates were dry foods, like nuts and chips. I will check with some other people around here and see if others have had your experience. Avoiding acidic foods makes sense, but noodle pudding seems pretty safe!

Our glass is used for plates that are custom made for restaurants, and I haven't heard any complaints, but one design that I know of is not fire-polished, and perhaps a fire-polished texture is more vulnerable than one that is sand-blasted before slumping. (This process tends to provide a more satiny finish that incidentally masks fingerprints.)

If your plates seem ruined, it might be worth trying a remedial process---fire the plates flat, sprinkle with an even layer of clear powder (1101-0008 or 1401-0008), refire to a fire polish and slump them again. Here is a link to a QuickTip on this technique: process:http://www.bullseyeglass.com/methods-ideas/quicktip-use-bullseye-clear-powder-to-fix-surface-flaws.html

Mary Kay
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Re: Food Stains on Glass

Postby eablitz » Wed Jan 09, 2013 5:26 am

Before trying such a drastic step, I'm going to try running one through another slumping cycle to see if it will just burn off the marks. What I want to know is if the marks are "on" or "in" the glass. It just doesn't make sense, noodle pudding just isn't that dangerous. I however, stored a cheese ball on a plate made with Crystal Clear and Red glass for a week and no marks were left behind. Could it be color specific? I'll let you know the results when I have time to run a slumping cycle.

I'll try to attach a picture. The noodle pudding was cut in small 1" squares, leaving a grid of an oil spill type color. If I continue to use the plate I imagine the squares will no longer be noticeable, but what I fear are customers returning expensive platters if they notice something along these lines. I'd love to have a solution if the case comes up.
Attachments
Plate defect.jpg
See the faint grid.
Plate defect.jpg (197.81 KiB) Viewed 7246 times
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Re: Food Stains on Glass

Postby marykaynitchie » Wed Jan 09, 2013 10:52 am

Great photo! It really helps us understand what you are seeing. Since the day that you originally posted, I have been asking around Bullseye and have some more information for you now.

It very well could be color specific. In general, opalescent glasses are more liable to show food stains. We seldom receive reports about this, but we did get one long ago about pineapple staining a glass plate, and we were able to stain some opalescent glasses with lemon slices.

There is a product that we tried years ago to remove a food stain and it worked. It also seemed to prevent the glass from subsequent stains due to contact with food, even after the solution was cleaned off the glass. It is called "The Stain Remover That Really Works" by Novacan in Canada. It contains hydrofluboric acid, and must be used with rubber gloves, good ventilation, and caution. I am not sure where you can buy it, but I did get some results from a google search.

This is not a common problem. However, a way to prevent the possibility of a food stain would be to design projects so that they are capped with a sheet of clear or other transparent glass.

Let us know if you decide to try the stain remover, and if it works.

Mary Kay
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Bullseye Glass Co.

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Re: Food Stains on Glass

Postby Kevin Midgley » Sat Jan 12, 2013 8:22 pm

Why not just routinely cap your coloured glass plates with clear?
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Re: Food Stains on Glass

Postby eablitz » Mon Jan 14, 2013 5:34 am

Thanks for looking into this. It is a shame that it could be a recurring problem. I can't find much information about hydrofluboric acid, except that it is highly corrosive and sounds like some pretty nasty stuff. I think I'll pass on that. I'll try refiring at slumping temperature.

As for capping it with clear, I've had problems in the past with hazing (see Nov. 2010 post), don't know if it was a particular batch of glass or what, but I won't use it for capping any more (and subsequently don't have hazing problems). I'm not sure what I'm gong to do in the future.
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Re: Food Stains on Glass

Postby eablitz » Tue Jan 15, 2013 4:58 am

Success! Heating to 1250 degrees removed the stains. If only my dishwasher could get that hot, but then I suppose I'd have other problems.

Thanks for looking into this problem.

Erin
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Re: Food Stains on Glass

Postby dr sawfish » Sat Feb 09, 2013 3:36 pm

i only ever sell my products as display or dry food only,i find the glass doesnt hold up for practical use as marks or scum get left behind on the surface
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