How was this done?

[Kelly Thorson]

A pretty little glass sign on ebay....looks like the dimension was all done by sandblasting or was it physically etched? The detailing in the letters is different though, I'm curious as to how it was achieved. By painting on some type of resist before blasting? Says it is circa 1900...you think? Judging by the camera dates I'd say they were a little confused time wise.

[Danny Baronian]

Face down acid etch as produced at Mr. White's Mental Health day gatherings.

A varity of resists could be employed including asphaltum, tempera or gum arabic.

[Roderick Treece]

Might be damar varish as well.

Roderick

[Kelly Thorson]

Now bear with me, but both of those answers surprise me.....
I thought it looked to deeply etched for acid, and how is it that if you etch something that deep it doesn't eat away the sides of thinner lines? To me it looks like the depth is greater than the width of the detailing marks .....sooo how come the acid didn't eat them up and "undercut" them?
Damar Varnish...how would you get this effect from that?
Yep I'm confused...it happens
Here's one from the back that somewhat shows the depth of the letters.

[Danny Baronian]

Same answer as the first.

Roderick may have meant damar as a resist, but he'll have to clarify.

Face down acid etch, about 2 - 3 hours. Acid will only do as good as the resist you use, including fine lines.

I did two pieces at a DM meet that were similar. Larry probably has pictures, and John Yarnell did a number of tests that yielded the same texture.

A search on the forum should have pictures from several mental health days and DM meets.

[Roderick Treece]

Kelly,
I didn't see the photo of the back which tells it all.
From the front you could get a similar look by doing an embosed center with damar vanish.

Roderick

[Mike Jackson]

Besides the acid etching, I have a good feeling the lettering would have been water gilded. I never tried, it but Rick talked about using a small stick or block of wood to clean off the excess gold on the flat part. By getting the small block wet, you'd wipe it over and over across the flat glass. That wouldn't affect the gold down in the depressions and make cleaning off the excess a fairly easy process. When done, the entire sign could be painted black, unless there were a few areas that needed color first.

Mike

[Danny Baronian]

Another way Rick suggested was to wrap a block of wood with a piece of brown paper bag, like grocery bags. Kraft paper would probable be the same.

According to Rick the paper acted as an abrasive to the gold, but not enough to harm anything else. Similar to the block of wood Mike suggested, and works well.

[Kelly Thorson]

Thanks,
BUT......What causes the pillowy tucked texture? Does it etch like that because the acid picks up impurities that then settle along the edges, or if the glass is lowered on acid are those air pockets. Or is that just how it is done.
Danny, when you say face down acid does that mean with the side that is being etched facing down in which case you are referring to the back as the face or does it mean with the face down which would mean back up? (I seriously have not figured that out.)
I guess I don't know how to drive that old search engine, 'cause I couldn't find anything that looked like that here and besides...I might have a problem with directions.
Now don't you feel sorry for all my old teachers! Actually I never had much school and the teachers that I did have all seemed to like my inquisitive nature.

[Danny Baronian]

I added to the confusion with my idea of face up. I'm thinking of the face as the surface you work on, but technically the face is the right reading face.

With that said, the piece you pictured is acid etched face up. Face up allows for a stronger acid solution, and can be submerged longer without fogging. It won't fog with longer times because removed by the acid drops to the bottom, producing a clean acid etched surface.

Etching face down for periods longer than 20 - 30 minutes will fog the glass since the slurry of glass and acid after that time will settle back onto etched areas. There's a name for the slurry that's formed in face down etching, maybe someone can help with the name for those interested.

This is a section from a face up etch by John Yarnell. The edges of the letter are rounded and have the same characteristics as the first picture posted.

[Mike Jackson]

I did a search for "tempera" and found this old thread:
https://handletteringforum.com/forum ... mpera#5072

Kelly,
Here's the basics: (remember your acid etching safety precautions)

Coat the front side of the glass with asphaltum so it is completly protected. The front in this case is the side you will see when the job is finished.

Screen or hand paint asphaltum or a workable resist on the back side of the glass, leaving the areas you want to etch exposed. With some tempera paint, make the extra little lines and texture designs. You might even use some diluted asphaltum?

When ready, place the glass in an acid bath front side up, sitting on small blocks or spacers, completely emmersed in the acid. The acid starts attacking the clear glass from the underside (back side of the glass) and gets a head start. Then, being water based, the tempera starts dissolving, allowing fresh acid to begin etching it. The small glass flakes and residue fall to the bottom of the container.

When etched to the desired depth, remove the piece and dissolve all asphaltum with mineral spirits.

Finish as described in earlier parts of the post.

Again, this is very dangerous. Refer to the MDS sheets before attempting any acid work!!!!! Take a supervised class!!!

Mike Jackson

[Kelly Thorson]

Well as usual my curiousity has cost me the better part of an evening.
But now I understand the chemical process that causes the etching. I was surprised to find that HF acid was first used to etch glass in 1670. As a matter of fact, I didn't know glass was invented back then.
So for those who don't already know and actually care.....
"the adsorption of the two reactive species: HF and HF 2 - and the catalytic action of H+ ions, result in the breakage of the siloxane bonds in the silicate network."
Typical to the convoluted path my mind seems to always take, I also found some interesting stuff in regards to creating frosted glass using ammonium flouride. The chemical reaction between it and the glass forms ammonium salts that grow in crystaline patterns over the surface of the glass. As they deposit they form a barrier that stops the acid from etching any further .
"The uncovered glass surface continues to dissolve and feeds the protecting layer that progressively extends and masks the rest of the glass. Dissolution is stopped when all crystals merge to cover the whole glass surface. After washing the ammonium salt with pure water, the roughness of the frosted glass is the negative shape of the crystal growth."
Ahhhhh, So thats how they do it!
Oh, oh, am I showing my nerdy side?

[DAVE SMITH]

Hi Kelly.
I made this little piece as a step by step a few years back using the techniques described here.
In some areas on the words P.H.Zang I was getting a clear deep etch and others a deep matt etch more so on the word Co .I used household emulsion for the resist which I think is the same as Tempra. I think poss on the sign your showing the lines in the letters would have been very thin to start with, once the etch was complete they would have appeared thicker towards the face


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Great effect for old work..
Dave

[Kelly Thorson]

Thanks Dave,
In a past post Pat said:

Remember that the nature of acid etching is that it etches wider as it etches deeper, so your fine lines may eventually join before you obtain the desired depth.

I misunderstood that comment to mean the opposite, I thought it meant it would eventually undercut the lines and make them dissappear. But as the etch gets deeper the actual etched area is narrower. I think I'm understanding now why that happens, because the silica bonds are only being broken down from one direction, which explains the puckered appearance along the edges.
Have you ever used the ammonium flouride method to create the fern like frosting that looks similar to glue chipping? (*Edited to add that I misunderstood and this happens on a microscopic level...sorry) It sounds intriguing, I love the way frost patterns form on glass. Any pics if you have used it? Is Ammonium Flouride as dangerous as Hydroflouric?
I just don't quit with the questions do I?

[Patrick Mackle]

The "pillowey" shape that results from placing the glass 'etch side down' into the acid is caused by the turbulance caused as the weightier silica granules unlock their bond from the glass and fall away causing the acid to circulate in and fill the void. It tends to create a sort of micro "alluvial fan" texture around the edges. The glass etches deeper because the silica falls away thus continueously exposing fresh glass to the etchant.

Ammonium Biflouride like HF acid also contains the dermal distructive flouride ion. AB in it's dry crystaline form is mostly a dust danger unless you had it in close contact, say like in your moist pocket for a period of time. In solution AB is more readily absorbed into the skin. HF acid can be more dangerous due to the fact that it is supplied in much higher concentrations and is always in liquid form.

I would bet that the sign you posted was etched in a single etch bath with a single screen print of acid resist including the "wisks" in letters.

Pat

[Kelly Thorson]

Thanks for the information Pat.
When I reread the "abstract" I realized that they were talking on a "microscopic" level...
Darn, I was liking the idea that you could acid etch fern patterns in glass. This imagination of mine sure can steer me wrong sometimes.
The sign sold for $126.50 for anyone who is curious.

[Danny Baronian]

Kelly,

since you've done the search on this subject, please post the information you've found from the Hand Lettering Forum, as Mike did with a search for tempera as an example. It will be helpful for all to have that forum information in one place.

Regarding acids and other additives, I'd suggest you contact a lab and talk with their chemist in order to know what intermixing chemical components will or will not do. That will take time, since most are reluctant to provide advice.

From experience most have liability concerns of potential claims that an accident was due to information they provided.

To have a head knowledge and a working knowledge of working with any type of chemicals - or any process - are two different things. For for anyone that's made up white acid, or silvering solutions, you quickly find it takes time to balance the ingredients. Do tests which will give and understanding of what can be done, as well as demonstrate the dangers of any missteps. Adding certain components too fast or in the wrong order will appear to be the makings of a explosive rather than a glass treatment.

If you need more information, contact a qualified chemist and conduct independent tests yourself, something beyond the scope of this board.

As usual, follow all safety information when using any type of acid or chemicals. Those warnings are well posted on this site.

Danny