Problems with glue chip

[Andrey Kolmakov]

Hello. I did made ​​my own asphalt varnish, but when i try glue chip, in some places glue removes varnish
Could this be because the lines are too thin? Or my varnish too liquid ????

[pat mackle]

You may have answered your own question with "I made my own asphalt varnish".
It sounds to me as if the your mixture is resulting in a film that has too high a shear strength (too much added varnish), and too little adhesion to the glass. In other words you should do a test of your mixture by coating it onto some clean glass and allowing it to dry. Then using a new razor blade, get under the edge of the dry film and lift it onto the razor blade without severing the attached film on the glass from the edge of the blade. Then place your thumb against the film on the blade to secure it and lift up and away from the glass. This test will tell you that if you can get under the dried film with the blade, and continue to lift and take more of the connected film off the glass, that your film strength (shear strength) is greater than its adhesion to the glass, and thus will pull up with the curling animal glue in undesirable sections. If properly formulated, when you first begin to left under the film with the blade, then lift the blade upwards off the glass, the film will instantly separate neatly at the very edge of the blade without lifting the slightest amount more from the glass.
There is also the added possibility that your mixture is inviting the animal glue to adhere to it, rather than repel it. Varnish attracts, oil/asphaltum repels.

[Andrey Kolmakov]

Thanks, Pat.
I have one more question. My varnish dries around 3 hour. It is normal ??? I read that your varnish dry 10 minutes.

[Larry White]

Eloquent Mr. Mackle...

Well, the reason for the asphaltum varnish is so if the glue overlaps
onto it slightly, it "pops" off, keeping a clean edge. So, to me. it is
behaving correctly.

It also appears that you masked over the asphaltum varnish,
sandblasted it, and peeled the mask off without the varnish
coming off, which is the way it is supposed to work.

A couple things that I see that may be factors are, it looks like your
sandblasting media is a little too coarse, and, the glue doesn't
appear to have been applied thick enough.

If the glue overlaps onto the varnish during application, it can be
trimmed and removed after the glue gels. If the glue "bridges" over
any area that is not to be chipped, it must be removed, or you'll
risk chipping out an area that was supposed to remain clear.

I don't know if that helps, but it gives you some considerations.

[Tyler Tim]

Andrey

I'm no expert in glue chipping. Thou it appears as if you flood coated the glass instead of trying to color the glue inside the lines. My understanding is any bridging should be scored along the edges of the feature to try and avoid pulling and popping after the glue has set up but still rubbery. And also that sharp corners should be X cut. Also it looks like your half to thin on your coverage. Hard to tell cause of the carpeting did it chip?


Edited to add
Larry posted before I hit submit (phone call)... He is an Expert

[Andrey Kolmakov]

Larry, thank you so much ! I appreciate your opinion. I will try again and again until I get perfect.

[Lee Littlewood]

Pat wrote:
"Varnish attracts, oil/asphaltum repels."
Is true?? I thought that varnish was solvent (oil) based, and so would naturally repel hide glue - it certainly makes water pull away.

Confused
ly

[Bill Ames]

A couple things that I see that may be factors are, it looks like your
sandblasting media is a little too coarse...

Larry,

What happens if the media is too coarse? This is the first I've heard of grit being discussed.

[erik winkler]

Read this Bill

[Bill Ames]

Thanks Erik. I knew how to glue chip the glass but I had never heard any issues with the sand blasting media being too coarse. I've had similar issues in the past with the chipping going outside of where it is supposed to. I think I have used 80 grit media.

I was wondering how the coarseness of the grit had an effect on the results of the chipping process.

[Andrey Kolmakov]

When i read "Rick Glawson's Review of the original Glue-Chip Process" , i understand that Rick does not use asphalt varnish. Only stencil . it means i can do without it?

[pat mackle]

To answer several questions in the above posts.
On the topic of varnish/asphaltum. Q: "my varnish dries in 10 minutes" A: I don't use a varnish as a resist, I use asphaltum based mixtures which I like to let dry for at least several days or longer. My loose description of a "varnish" would be something like a shellac, or oil size, or a transparent sealer of sorts, the term "varnish" may be "coined" to refer to such materials unless a specific manufacturer is mentioned.

Lee. On the topic of glue adhesion to varnish over asphaltum. A: I find that animal glue will bond to straight dried varnish but not asphaltum. Therefore a higher percentage of asphaltum must be added to straight varnish to lessen the bonding. The varnish helps thin the asphaltum, speed the drying, and give it body when dry.