What's the best way to coat metal plates with Liquid Light emulsion?

Bruce Schultz · Mar 24, 2007

I just coated my first set of metal plates using the Rockland kit with Ag Plus emulsion. I had my emulsion pretty warm and I tried spreading the emulsion with bare fingers but it seemed pretty blotchy. Is there a way of getting a nice, even coating?

Sparky · Mar 24, 2007

what might be a good way to spread... oh, let's say PAINT on a surface...?

Bruce Schultz · Mar 24, 2007

I tried a brush.

It was uneven and splotchy also. I'm thinking I need to warm up the plates so that the emulsion doesn't cool down when it is poured on the surface.

agGNOME · Mar 24, 2007

Hi Bruce,
Are you using any subbing material? Metals need to be cleaned (try alcohol), then coated with polyurethane..dried , then coated with liquid emulsion

Bruce Schultz · Mar 24, 2007

I'm using the plate material from Rockland that's already painted. One problem I'm having that may be leading to my difficulties: the directions with the kit recommends a thin coat, so should the coating be thin enough that you can still see the black surface of the plate?

Photo Engineer · Mar 24, 2007

Coating with a brush will always leave some brush marks. Spraying the emulsion on is another option just as you might use paint and spray it on.

Foam brushes work but often leave bubbles.

Wire wrapped glass or steel rods work well but are messy.

The coating should be at least 0.002" and not more than 0.01" thick and show no or as little black plate as possible.

PE

magic823 · Mar 24, 2007

I'm with PE

I've used a hvlp sprayer (same type used in woodworking) to spray liquid emulsion on canvas. Its the only way I've found to get an even coat.

Photo Engineer · Mar 24, 2007

The difficulty in coatling liquid emulsions is why I came up with the coating blade.

But in any event, one trick to better uniformity coating any emulsion is to use a spreading agent such as photo flo. One half ml / 100 ml of emulsion should help a lot.

PE

Bruce Schultz · Mar 24, 2007

Tell me more about the coating blade, PE. WHere do you get one or how is one made?

richard ide · Mar 24, 2007

PE
Is that photo flo concentrate? and if so which of the 3 concentrations?

Thank you

Photo Engineer · Mar 24, 2007

Richard;

It is Photo Flo 200 concentrate. The 600 can be used, but you should use a lot less.

Bruce;

See the Photographers Formulary for pictures and prices, you can also see my posts here on APUG.

PE

kevin klein · Mar 24, 2007

Liquid light is too thick for an easy even coat. If you heat the plate befor coating the emulsion will start to cool the plate and still get uneven. The best thing is to heat the plate from the under side after pouring off the extra emulsion and move it around to coat it evenly.

Photo Engineer · Mar 24, 2007

Kevin has a good point. Using the plate coating method will work well with a heated plate and by pouring on the Liquid Light. In that case, if it is too thick you could dilute it with a small amount of Everclear (95% ethyl alcohol with no denaturing agents).

PE

Bruce Schultz · Mar 24, 2007

I'll try the plate warming idea. It makes sense the emulsion congeals as soon as it hits the cool metal, I expect to see a big difference. If not, I will have proven to myself that I should just wait until the collodion workshop I'll be attending in a couple of weeks.

smieglitz · Mar 25, 2007

If the stuff is anywhere near similar to wetplate collodion you should be able to pour a pancake-sized puddle of emulsion in the center of a horizontally-held plate and swiftly flow the emulsion by tilting the plate towards each corner, then up vertically to pour the excess off. There are several ways to hold the plate while doing this, but I prefer the "waiter tray" method.

If the emulsion is too thick I would second the suggestion of diluting it with Everclear 190 proof grain alcohol.

Quinn Jacobson has a You-Tube video in which he demonstrates the collodion technique:

http://www.youtube.com/watch?v=Gyf8fQOdvDs

Joe

nworth · Mar 27, 2007

The printed circuit and chemical machining people often spin coat resist emulsions onto metal. The photo emulsion is thicker than KPR, but the technique may still work. For non-production work, you could put a hot plate in the bottom of a drum to keep the work area warm and then use an electric screwdriver to spin the work (at a fairly low speed). Some sort of a wire holder could be rigged to hold the plate. It is important to keep the plate fairly level during spinning in order to get an even coat.

colivet · Mar 28, 2007

PE, will those blades work for other processes like maybe Carbon or Albumen?

stormbytes · Mar 28, 2007

magic823 said:
I've used a hvlp sprayer (same type used in woodworking) to spray liquid emulsion on canvas. Its the only way I've found to get an even coat.

Hi,

Could you please elaborate on the type of unit you use? I've seen a couple on ebay (units and "brushes" or whatever they're called). I'm actually looking at a nice reconditioned Wagner.

Any help & tips would be appreciated.

Photo Engineer · Mar 28, 2007

colivet said:
PE, will those blades work for other processes like maybe Carbon or Albumen?

Yes, they work with other processes. Sandy King and I worked with and coated some carbon sheets last spring using one of his formulas.

Just because it works, does not mean that it is optimum though. As Sandy pointed out, due to the thickness of the carbon required, other methods function just as well as the blade.

PE

sanking · Mar 28, 2007

Photo Engineer said:
Yes, they work with other processes. Sandy King and I worked with and coated some carbon sheets last spring using one of his formulas.

Just because it works, does not mean that it is optimum though. As Sandy pointed out, due to the thickness of the carbon required, other methods function just as well as the blade.

PE

You can definitely use the blade to coat carbon tissue, though it would need modification to coat as thick as I like. And even with the modification I don't believe the blade would be *more* effective than my present system of coating carbon tissue, where I roll a heated tube or rod over the warm pigmented gelatin to even it out, with the final height determined by the thickenss of the flexible magentic sheeting frame which forms the borders.

I have also used a threaded rod to coat carbon tissue, and a rod might work with some of the coating procedures being discussed. Check out this source for threaded rods and other types of coating devices. Dead Link Removed

Sandy

Photo Engineer · Mar 28, 2007

Sandy is exactly correct.

PE

colivet · Mar 29, 2007

Thanks Sandy and PE. It seems clear the rod and sign material is easier for carbon. Maybe the coating blade would work well for albumen since you can adjust the thickness of the coating with the blade instead of using the double floating method.

Dave B · Mar 30, 2007

Photo Engineer said:
Kevin has a good point. Using the plate coating method will work well with a heated plate and by pouring on the Liquid Light. In that case, if it is too thick you could dilute it with a small amount of Everclear (95% ethyl alcohol with no denaturing agents).

PE

I'd just like to add that the victims, err subjects, of the Florida kleptocracy can not buy or possess ethyl alcohol above 153 proof under penalty of felony charges. Everclear 151 proof ( 75.5 % ethyl alcohol ) and the identical Graves Grain Alcohol 151 proof are available in South Florida, and legal to own.

Photo Engineer · Mar 30, 2007

We have the same problem here, but we are at least allowed to possess it here in NYS.

DO NOT UNDER ANY CIRCUMSTANCES USE DENATURED ALCOHOL....

This warning holds especially if the denatured alcohol becomes cloudy when poured into water.

I was given this warning at EK, and so I have never tried to test it, deeming my hand and machine coatings too valuable to mess around with. Besides, we were not permitted to have denatured ethanol in the labs. We used 95% or Absolute (99.99%) ethanol.

PE

Dave B · Apr 1, 2007

Would the drugstore stocked isopropyl or methanol available in 90%+ be usable for thinning ?

What's the best way to coat metal plates with Liquid Light emulsion?

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