Gum print Contrast

[Bruce]

How do you get a glossy looking Gum print versus a dull - flat looking print?

 

[Como]

Gum prints have a short scale. So you get either dark tones, middle tones or light tones.
To get more contrast you have to make more layers with different combinations of dichromate/pigment/exposure time:

dichromate exposure pigment
highlights more longer less
midtones normal normal normal
shadows less shorter more

 

[koraks]

How do you get a glossy looking Gum print versus a dull - flat looking print?

So do you want to know about surface finish or contrast? For glossy I'd coat the finished print with for example wax or even a fairly heavy gelatin topcoat.

 

[Dan Pavel]

The gum print is not much different of a traditional gum-based watercolor paint. You can coat your gun prints with traditional watercolor painting varnish.

 

[Bob Carnie]

So do you want to know about surface finish or contrast? For glossy I'd coat the finished print with for example wax or even a fairly heavy gelatin topcoat.

I would be very interested Koraks if you gave me the working formula for the gelatin coating you are using, I would like to try this. Also if so kind you could post a before and after jpeg if you have this.

 

[Bob Carnie]

The gum print is not much different of a traditional gum-based watercolor paint. You can coat your gun prints with traditional watercolor painting varnish.

Would you be so kind to describe Varnish ... its components to me this sounds caustic?

 

[Bob Carnie]

I only use one paper for my Gum printing hahnemuhle platinum rag, in my case I love the matt look but would be open to suggestions for a different paper base to build up gloss. I am curious as well about this.

 

[koraks]

I would be very interested Koraks if you gave me the working formula for the gelatin coating you are using, I would like to try this. Also if so kind you could post a before and after jpeg if you have this.

My method was a proposed one, not one I use. But I'd start with something like a 2% gelatin solution and then brush coat, applying up to 3 layers with drying in-between. Hardened with glyoxal or chrome alum. Essentially exactly the same way as preparing final supports for carbon transfer. 3 coats of 2% gelatin results in a bit of an eggshell semigloss.
I suppose a single, heavy coat could be poured on but you may have some issues with wrinkling, bubbles etc. so I'd have more confidence in brush coating multiple layers.
If you tape the paper flat using gummed tape it should be possible to end up with a perfectly flat print, just like with fb silver gel paper.

 

[nmp]

I use Liquitex High Gloss acrylic varnish on my inkjet-printed canvas, mostly for protection, but a couple of brush-coats gives it a nice sheen too. I guess that would work on gum prints as well.

 

[removed account4]

Bob,
Have you ever used renaissance wax? i know its used for a variety of different things to gloss and protect.
John

 

[Dan Pavel]

Would you be so kind to describe Varnish ... its components to me this sounds caustic?

For instance: https://www.goldenpaints.com/technicalinfo/technicalinfo_varnwatercolor
Some of the best watercolor Varnishes are, IMO, made by Lascaux. I have tested some of them with nice results.

As long as an acrylic paper size is safe to use with gum prints some other acrylic watercolor varnishes may be, IMO, safe to use, too. However, I have not tried them yet.

 

[glbeas]

The only downside to varnish is eventual yellowing as it ages. Maybe theres newer formulas out there that dont but Im not familiar with them.

 

[Dan Pavel]

The only downside to varnish is eventual yellowing as it ages.Maybe theres newer formulas out there that dont but Im not familiar with them.

I wouldn't bother too much. Painters used varnishes for centuries and the yellowing process proved to be quite slow with the traditional varnishes.
After all, if the print is considered valuable it will be restored by the future generations and if it's not considered of any value then who cares?

 

[Andrew O'Neill]

I occasionally use a medium gloss acrylic medium varnish. Four coats, diluted 1+1 with water. I like the slight increase to dmax and saturation. The image on the bottom is the gloss varnish print. I took a photo of the print before I coated it.

 

[Bob Carnie]

The only downside to varnish is eventual yellowing as it ages. Maybe theres newer formulas out there that dont but Im not familiar with them.

This is kind of my worries with any laminate that is put over a print or any material

 

[Andrew O'Neill]

This is kind of my worries with any laminate that is put over a print or any material

I have kallitypes that I coated with acrylic varnish 15 years ago that show no signs of yellowing. They're hanging on my wall.

 

[glbeas]

If I remember from my woodworking studies acrylic varnish is one of those that does not yellow. Not favored by some as the warm tones of the oil based varnishes are desireable. In this case it works in our favor.