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Screen Printing Acid Resist on Glass?

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

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William Holohan
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Location: Marlborough, MA

Screen Printing Acid Resist on Glass?

Post by William Holohan »

Is it possible to screen print an acid resist on glass that would be good enough to last for 3 - 5 minutes...I have to think this has been answered befor , but could find no reference to it anywher..

Thanks for any input

Irish
Doug Bernhardt
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Post by Doug Bernhardt »

Asphaltum....end of story! Just paint in or print all the arae's to be left clear. It DOES get interesting when you start to do all the different types of acid etching...white acid deep...and mica! Look forward to seeing the results!
Mike Jackson
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Post by Mike Jackson »

Doug is right about the asphaltum. You can paint it or screen print it.

There are a couple of caveats however! At the Conclaves, they often screened the asphaltum resists, but you would later find each person at the light table filling in all the micro holidays with asphaltum using a small brush. If you don't do that, the acid will find every single one of them. That might not be such a problem if silvering, but if you were to Angel Gild the glass, the gold will get into each tiny pit and you cannot clean them out. Silver strip will remove the silver ones. They just disappear when the silver strip hits them.

We tried double screening asphaltum with off and on success. The asphaltum will self dissolve slightly on the second screening and will want to stick to the back of the screen. We tried dusting the first coat with dry asphaltum powder using a pounce bag and that helped some. Eventually, we found we got our best results using a more coarse screen which will deposit more asphaltum on the first run and will often self heal in the small dots. Acid etching is not as critical in most designs as the final lettering and outlines will be in later steps, so the more coarse screen is not an issue.

When we were doing groups of around 15 pieces, we often had to solve problems like this that might not be much of a problem with one-off signs. I used to call it "steady resistance". We made progress but we had to work out the little speed bumps on the fly.

Mike
Mike Jackson / co-administrator
Golden Era Studios
Vintage Ornamental Clip art
Jackson Hole, WY

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William Holohan
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Joined: Mon Apr 12, 2004 9:13 pm
Location: Marlborough, MA

Post by William Holohan »

Thank you Mike J and D. Bernhardt. Absolute novice at this stuff. Getting adventurous for an old Geezer since the Mass Mayhem meet. Sandblast cabinet complete except for foot pedal. Glue chipping supplies whisper to me every time I pass the shelf they are on. No one ever warned me of their ghostly talents. Should be trying my first piece within the next week.
Mike Jackson
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Post by Mike Jackson »

William,
Screen printing the asphaltum would not be a necessary step for glue chipping, only for acid etching (WARNING: DANGEROUS). For glue chipping, you coat the entire piece first, then frost the open areas of asphaltum away with a sandblaster.

There is a TON of information about glue-chipping if you go to:

http://www.theletterheads.com/lhparts/gluechip.html

Good luck,
Mike Jackson
Mike Jackson / co-administrator
Golden Era Studios
Vintage Ornamental Clip art
Jackson Hole, WY

Photography site:
Teton Images
Jackson Hole photography blog:
Best of the Tetons
William Holohan
Posts: 93
Joined: Mon Apr 12, 2004 9:13 pm
Location: Marlborough, MA

Post by William Holohan »

Mike,
Doing some of both. Small blast cabinet 20 x 28 for the chipping, Also trying acid etching. Vinyl mask and craft store etching cream to get a feel for it right now.

Will not attempt deep etching till I've got the right ventilation/respirator etc and stainless cabinet in place. Disposal of waste is anoter concern. Local plating co will take any waste at a small fee.

Have printed out and read/re-read almost everything from the old site. Hope it stays up for awhile, I want to re-explre and make sure I didn't miss anything buried in an unrelated thread.
Mike Jackson
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Post by Mike Jackson »

William,
When using the Etching Creme, you can simply print it directly ONTO the glass through a screen with a bit of a coarse mesh. No need for asphaltum on this one at all. The creme acid I bought has a rough texture, almost like it has sand mixed in. I didn't use it enough to know, but I'd bet it is hard on the squeegee edges. I've used it, but it doesn't produce the etch I like.

Good luck,
Mike Jackson
Mike Jackson / co-administrator
Golden Era Studios
Vintage Ornamental Clip art
Jackson Hole, WY

Photography site:
Teton Images
Jackson Hole photography blog:
Best of the Tetons
Doug Bernhardt
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Post by Doug Bernhardt »

Another quick aside....the etching creme can easily be used with just a vinyl mask....once you DO get into the hydrofluoric remember also there is another side to the thing and make sure the fumes don't get at it...have enjoyed this thread Goldie!
Till later
Mike Jackson
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Post by Mike Jackson »

William,
While 49% hydroflouric acid is VERY DANGEROUS, it gets less dangerous as it gets diluted. For example, one ounce of 49% acid has only 1/2 oz of pure acid. If you add one more full ounce of water, the precent drops to 25%. Add two more ounces of water and it drops to 12% (just by adding 3 oz of water to the first ounce). If you added a whole gallon of water (64 oz) to the original 1 oz of 49%, the precentage of acid to the gallon is very low.

The acid creme has something like 10% acid and you can handle that with household rubber gloves...and it is sold in many craft stores.

If my math is incorrect, someone please correct me. I don't want to give out bad advice, but by the time you dilute an acid solution with a couple gallons of water, it becomes mostly harmless.

Best regards,
Mike Jackson
Mike Jackson / co-administrator
Golden Era Studios
Vintage Ornamental Clip art
Jackson Hole, WY

Photography site:
Teton Images
Jackson Hole photography blog:
Best of the Tetons
Emma Lindsay
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Joined: Mon Jun 26, 2017 11:43 am

Re: Screen Printing Acid Resist on Glass?

Post by Emma Lindsay »

Hi,

I see this is quite an old thread but I have been searching a long time for a acid resistent screen printing medium for glass which seems really hard to find. Can anyone tell me more about the Asphaltum? How to mix? (comes in powder form?) and how to clean it off the screen afterwards?

Thank You
Lee Littlewood
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Re: Screen Printing Acid Resist on Glass?

Post by Lee Littlewood »

Hi Emma,

If you go looking for "asphaltum" you'll find a lot of varying information. Since it is a natural substance (some sort of petrochemical 'tar') that makes sense, still it is irritating if you're trying to be consistent.
But for block-out screen printing you can buy a quart of "Roof Patch" or similar gunk and thin it with paint thinner. The more refined asphaltums that are made for artist use (copper engraving?) are overkill for this use.

Dilute the gunk to a normal ink consistency, and maybe a tiny bit wetter. Use minimal off-contact, flood coat and pull slow - it won't flow out like screen ink and you don't want bubbles to turn into pinholes. Give it time to dry, but overnight is probably enough. Remember it will self-dissolve, so be quick when you're spotting out holidays.
Clean your screen with paint thinner or lacquer thinner. We like to use haze remover on our screens most of the time anyway, and that'll take out any lingering film.

And of course BE CAREFUL with hydroflouric acid. Roderick Treese has a good safety thread on his website.
where am i? Now, when i need me...
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