An Experement

[wildbillbugman]

Hi ,
My most recent method was to use an RD Specialties #40 wire rod, wet thickness according to their chart,3.6 mils. I use 2 layers of scotch tape and measure just bairly 8 mills wet thickness. Something made 0.6mils disapear.
Seriously though, I don't have a Brookfield viscometer. But I am absolutely certain that all of these emulsions, gelatin or PVA based, are thixatropic. That is, viscosity ,and therefor rate of flow, are influinced by shear. The faster the draw-down,or the faster the squirt from a syringe, the lower the visositry, and that means more emulsion flowing faster. In the case of PVA based emulsions, there is no thickening due to setting of the emulsion. Therefor the coated emulsion is subject to flowing until the water evaporates.
Bill

 

[Kirk Keyes]

Hi ,
Seriously though, I don't have a Brookfield viscometer. But I am absolutely certain that all of these emulsions, gelatin or PVA based, are thixatropic. That is, viscosity ,and therefor rate of flow, are influinced by shear. The faster the draw-down,or the faster the squirt from a syringe, the lower the visositry, and that means more emulsion flowing faster.

Many years ago, I used to use a Brookfield viscometer at work. I don't think it will work well with thixatropic materials. It uses different diameter and shape rods, wheels, and drums to measure the viscosity.

I once had to test blueberry jam with it - it needed a rod that was about 5 mm in diameter for material that viscous. But you would get a much higher reading just after you turn the Brookfield on and a much lower one after a minute or so, as the viscometer wheel would be dragged by the blueberry chunks in the jam at the beginning and then it would pull the thinner jam around it as it spun. I think you would have the same sort of issue with your "emulsion".

(I also had a high viscosity Standard that I used for verifying it's function. It was a silicone "liquid" - you could take the jar and lay it on it's side with the lid off, come back in 30 minutes, and the liquid would just be "pouring" out the bottle. The fun part of this trick was to catch it before it touched the countertop!

But that's a really cool test shot, Bill! I'm looking forward to more photos!

 

[dwross]

... In the case of PVA based emulsions, there is no thickening due to setting of the emulsion. Therefor the coated emulsion is subject to flowing until the water evaporates. Bill

It sounds like your emulsion is a perfect candidate for a plate surrounded by thicker dam bars. If you placed all the glass on silicon sheets and pressed them down for really good contact, I'd think the emulsion would stay put long enough to dry nice and even.

I've found this a great silicon sheet: http://www.target.com/gp/detail.htm...110944&ci_sku=B0002MH2HA&ref=tgt_adv_XSG10001

 

[wildbillbugman]

Yes Denise,
I certainly plan to try it. But that will have to wait until I receive my order of more glass plates. I am down to 8 plates suitable for emulsion plates. I do not use common windowglass. I use Tru-Vue Clear Glass. This is what I use for my finished glass art. It is less green than window glass, but not as expensive as "Iron-Free Water White Glass".
But I think I need a little break now. I tend to work all day and into the next morning. I am feeling a bit exausted. Its the computer and books for me for a couple of days
BTW I strongly recommend Tru-Vue for anyone who pants to print anything on glass. There is a regular dealer on ebay who sells several types a very reasonable prices.
Yes,Kirk
I too have experience with Brookfields. Even without chunks of blueberries, a homogenous thixotropic liquid, such as various types of traditional printing inks, will start off with a higher reading. Given a constant temperature a reading will decrease until it reaches a constant for a given rate of shear. Increase the shear (higher RPM) and. in a thixotropic liquid, the viscosity reading will fall.
Bill

 

[wildbillbugman]

My little vacation is extended a bit. I am now holding off until I receive more of the R-Polymer. I am out now.
B&S has indicated that they will be ordering a 20kg sack. That is the Kuraray minimum order . So, if anyone is interested in giving it a try, Kuraray will send you a pound for free. But it looks like it will be availible from B&S. 20 kg is a bit too much to have laying around.
Bill

 

[holmburgers]

Do you think that this polymer stuff would imbibe dyes? Would it stick to completely raw (unsubbed) melinex?

The reason I ask is, if you could coat a layer of this polymer, and have it not lift off of unsubbed melinex, you could then coat a gelatin emulsion for subsequent sensitization and etching using the carbon method. However, it should not be able to imbibe the acid dyes used in dye-transfer processes or else you can't really get clean & clear highlights.

PhotoFormulary has a subbed melinex which is awesome, but I understand it's a somewhat limited supply and who doesn't like an alternative?

Just a thought!

 

[wildbillbugman]

I do not think that the R-Polymer would adhere to melanex. The Silane functionality works only for glass and other Si containing surfaces. Dave Pitcher has tried it on Plexiglas with, I think, little success. Kuraray dose make an anionic and a cationic functional PVA.

 

[dyetransfer]

Do you think that this polymer stuff would imbibe dyes? Would it stick to completely raw (unsubbed) melinex?

The reason I ask is, if you could coat a layer of this polymer, and have it not lift off of unsubbed melinex, you could then coat a gelatin emulsion for subsequent sensitization and etching using the carbon method. However, it should not be able to imbibe the acid dyes used in dye-transfer processes or else you can't really get clean & clear highlights.

PhotoFormulary has a subbed melinex which is awesome, but I understand it's a somewhat limited supply and who doesn't like an alternative?

Just a thought!

You should try coating unsubbed polyester with a very thin (diluted) coating of Shellac. The solvent is Ethanol. I'm not sure how well it will coat on raw polyester, but it is worth a try. I do know that it works as a subbing layer, will adhere to polyester well, doesn't pickup any dye, and will hold gelatin quite strongly. You could probably get a print coating machine (used in photolabs) to coat sheets of polyester. I think these machines are used with solvent based coating materials. This would be used as a subbing layer, specifically for Matrix film use.

Regards - Jim Browning

 

[DPVisions]

I do not think that the R-Polymer would adhere to melanex. The Silane functionality works only for glass and other Si containing surfaces. Dave Pitcher has tried it on Plexiglas with, I think, little success. Kuraray dose make an anionic and a cationic functional PVA.

I have tried without success of having PVOH polymer, both the Kuraray R-1130 and Poval 217, work well as a coating onto plexiglass. Coating is easy and when dried is hard and adheres well. Once in gets in contact with water again it will float and/or peel off. Both polymers need heat to cure and become insoluable in water and heat required is not good for plexiglass.

As Bill pointed out you can get use one of the anionic polmers such as KL-318 and it will hold strong onto polyester but is still water soluable and will disolve unless crosslinked or heat cured.

Polyvinyl butyral(PVB) works as a subbing agent for plexiglass, PET, PETG, and is only soluable in strong solvents, such as ethanol. Never tested to see how well a gelatin size/emulsion adheres since my experimentation has around removing gelatin from the equation.

Cheers,
David