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Blistering Paint Outlines on Glass Gilding

Hand Lettering topics: Sign Making, Design, Fabrication, Letterheads, Sign Books.

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Bruce Buckley
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Joined: Mon Mar 27, 2006 10:33 pm
Location: Chicago, IL
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Blistering Paint Outlines on Glass Gilding

Post by Bruce Buckley »

Hello, all!

I recently posted the following on the Letterville BullBoard, and was urged by several to re-post it here for even greater response:

I realize the topic I'm introducing may only concern a handful of people, but here goes. My partner, Robert Frese, and I have been specializing in gold leaf window lettering for quite some time. Over the last couple of years, we've noticed the paint outlines (and sometimes the gold leaf itself) lifting off the glass in little blisters or bubbles a day or so after the job is completed. Except for the blisters, the rest of the lettering seems stable and perfectly adhered to the glass.
I assure you that we are fanatics about meticulously cleaning the glass beforehand with several applications of Bon Ami, so I'm pretty sure glass contamination isn't the problem. No doubt the fault lies in the paint we've been using, a mixture of One Shot lettering enamel, Ronan Japan Color, quick rubbing varnish or quick gold size.
I should explain that Robert began adding One Shot enamel to the traditional Japan/rubbing varnish mixture many years ago to improve flow, opacity and durability. After letting the painted outlines dry overnight, Robert would water gild over them the next day with excellent results.
We're wondering if the problem could be One Shot's more recent lead free formulations. After some experimentation, I've found that I don't have the blistering problem when I eliminate the One Shot.
I have the feeling that One Shot just doesn't cure hard enough on the glass to avoid penetration by the water size. (By the way, I tried adding One Shot hardener and still wound up with blistering a few days later!)
Unfortunately, I'm back to the problem Robert was trying to solve by adding One Shot in the first place... the traditional Japan/rubbing varnish mixture is grainy, not very opaque, pretty gummy after a short time in the brush, and not very durable when scrubbing away the excess gold.
What do others use for outlining single gild glass lettering? We need something that flows well in the brush and is very durable so that we can water gild over it and clean off the excess leaf without any trouble... or blisters.
Any thoughts or suggestions, folks?
Thanks!
Bruce
--------------------
Bruce Buckley
Chicagold Sign Co.
2252 N. 76th Ave.
Elmwood Park, IL 60707
Dan Seese
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Joined: Tue Apr 13, 2004 11:29 pm
Location: Fort Collins, CO
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Post by Dan Seese »

Hi Bruce,
I don't have an answer for you but I have run into this myself on a couple of occasions. I think your assesment that it is tied to the One Shot may have some merit since, if I understand correctly, enamel paint dries with a slick film, not only on the air side but also on the glass side so it doesn't adhere to glass as well as Japan Color. Also, my guess is that when we follow the outlines with other steps without allowing the layer of paint against the glass the time to dry adequately (as is usually the case) before it is "sealed" by subsequent paint or gold, it sometimes will bubble as it attempts to out-gas.
It seems like where I've run into this has been when the sun hits it and it gets really hot while it is still trying to cure.
I've never had a problem with anything I've done that is not exposed to the sun (like a mirror or an interior project.) Possibly under normal drying conditions, gelatin size and other layers of paint have enough porosity to allow it to dry but the super-heating of the sun or other elements force it to bubble. Has sun been a factor in any of your failures?
Your theory that the water size is penetrating the One Shot could be a similar situation where water is being trapped in some kind of pocekets before it is backed up but I suspect it is more a problem of the paint itself trying to cure.
Just my thoughts on it, but maybe someone with more understanding of physics and chemistry will have a better answer.
I guess I've given no solution but possibly some hints as to the cause. Since what you're looking for is opacity and the nice flow that One Shot lettering enamels give to the paint, maybe you could try adjusting the proportions until you find a happy medium. I haven't tried experimenting with different steps and exposing them to the sun but it might be worth a try.
Hope this helps.
Say hi to Robert.
Dan
Doug Bernhardt
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Post by Doug Bernhardt »

Hi again Bruce, I was directed to your post on Steve's site and when I got there I saw it was answered really well by folks we all know well. I'm with many others and say...stay the heck away from one-shot for this. The Dekkor with hardener as John mentioned has always worked for me and have used this for the better part of 10 years....no probs ever. Good sound cleaning (3 times) and things should be fine. The Dekkor stays self solvent for some time, making multiple oil decoration difficult...the hardener solves that. Say hi to Robert from me. He was an amazing host several years ago when I visited there.
Kent Smith
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Post by Kent Smith »

hope you saw my update on Lettervile as well.
Robert Schwieger
Posts: 123
Joined: Wed Feb 07, 2007 12:38 pm
Location: Nebraska

Post by Robert Schwieger »

I have been unable to get Dekkor (for backing up gold on glass) in quart size. Is there a source for this product?

Thanks. Bob
John Studden
Posts: 150
Joined: Wed Jul 28, 2004 11:40 am

Post by John Studden »

I answered this question once before, Buy some Back Up Enamel from Ron at Letterhead Sign Supply & add a few drops of one shot hardener or the equivalent, We have used this for years with no problems..One Shot black has no place in backing up or outlining a Gold Leaf job...
John Studden
Valencia Signs, California
John Lennig
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Location: Burnaby, British Columbia, Canada
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Post by John Lennig »

John, what is your choice for any thinning, usually done on the pallet from a sep. "thinner cup"
thanks.

John Lennig
"You spelled it wrong!"
John Studden
Posts: 150
Joined: Wed Jul 28, 2004 11:40 am

Post by John Studden »

John, Just regular paint thinner, with a brush....Naptha if you are screen printing....
John Studden
Valencia Signs, California
DAVE SMITH
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Joined: Sat Jul 10, 2004 11:12 am
Location: ENGLAND

Post by DAVE SMITH »

Hi Bruce.
Same as John I am also using the traditional back up enamel and hardner but only recently started using a screen enamel called Polyscreen PS. I have used it for silvering over with chemicals- it dries so hard to the glass that you can'nt scratch it off ,there is a downside to the drying times which are about 2 -3 days so only any good for shop work but it does work if you have a little more time and its brushable. I think this enamel is possibly the same as the backing paint we already use but the catalyst is different. The brand is Sericol and I think Bruce Jackson uses it in Australia for his work. He made some posts along with Mike on this subject a long while back now. I guess the best route to go is as John has stated as it works and works well ,I just needed something stronger for chemical application for blackoutlines. goodluck and say hi to Robert from me also.
Dave
Doug Bernhardt
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Joined: Fri Apr 09, 2004 9:29 am
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on to something?

Post by Doug Bernhardt »

Dave.....those pictorial glass pieces from the Tottenham on Oxford St. what would the old masters have used there. The pictorials were done before silvering and have only heard minor mention of paints used before silver at that time. Do these polyscreen come in colours?
DAVE SMITH
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Joined: Sat Jul 10, 2004 11:12 am
Location: ENGLAND

Post by DAVE SMITH »

Yes I know the ones your talking about Doug,I guess the paint back then would have had alot more lead and goldsize in the mix. The earlier glass panels were made for the same reason as that they never had a paint good enough.
I understand it was not until the early ninties that a development of a good protective paint for silvering over was discovered.
Polyscreen does come in colours. I will try and find out for you. but you could carry on using the japan range for pictorial or lettering and just protect the final coat with polyscreen prior to silvering.
which works beautifully.
Dave
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