Need advice for engaging dry plate.

[Pere Casals]

The lack of vision is the problem,

You can use an IR night vision toy: search amazon.com Spy Gear Ult Ninja Night Vision , $24 https://www.amazon.com/Spy-Gear-Ninj...t+vision+ninja



It´s only a toy but it allows to test night vision in the darkroom, If that way works for you then later you can acquire a more serious model.

[andrewch59]

A question for the more knowledgeable, does the emulsion go off? I had two black bottles in the fridge. I melted the emulsion down and even put a magnetic mixer in the bottles to smoothen the elixir out. When I tried to use it, it had some lumps in it which were hard to smooth down. Ended up as another big mess, as I then tried to pour the puddle and spread the old way, emulsion everwhere, more over the bench than on the glass.
Losing faith rapidly, when trying to pour, the flow would halt and was very hard to get started again, perhaps the glass was too hot??

[Nodda Duma]

Can’t say without knowing what your temperatures are or what you are using for emulsion. Not all emulsions are the same.

I melt and hold mine at 40C, apply with syringe onto plates at room temp, and spread with a glass rod. They then have several minutes to flow and self-level. But then, I am sure I’m using a different emulsion recipe than you.

It sounds like you are using pre-made emulsion. Their gelatin content is almost unworkably high for hand-coating dry plates, in my opinion. Mine is 6% and coats just fine. My guess is theirs is more like 10-12% and is a messy pain in the butt.

You can help yourself a little by adding everclear (surfactant) at 40ml / L, but you are better off mixing your own from a lower gelatin content recipe. 5-8% is best for hand-coating dry plates, IMO, giving enough working time to do a good job with less mess.

[seezee]

Hello Andrew,

I use the coating table I described in this post: http://www.largeformatphotography.in...=1#post1401868

Pere, what materials did you use? Did you glue it together?

[Pere Casals]

Pere, what materials did you use? Did you glue it together?

I use a bit of 3M Re Mount spray glue, because I use the same table to coat different plate sizes, if you only want to coat a single size you can use any kind of adhesive, silicone for example.

My base glass is 8mm thick. You can also use a mirror as a base glass. Mirrors have a better flatness than common glass.

[andrewch59]

Nodda, I have made my own using Mark Ostermans recipe. Once I make the puddle it will pour, then suddenly stop all motion and it take a lot of tilt to get movement again. Of course once you get the flow happening again, it takes off across the plate, and on to every flat surface in the darkroom. Will have to re-check temperatures, perhaps I have everything too hot. I see now there are several new recipes on The Light Farm website. Which one do you use??

[Nodda Duma]

Osterman’s recipe on The Light Farm?

In step 2, when you add the gelatin to water, you can inadvertently make it too runny if you don’t use the right ratio of water.

To bloom gelatin properly, add the gelatin to 8x the amount of water in ml.

So in step 2 add the 18g gelatin to exactly 144ml of water which will let it bloom properly. This will result in about a 6.6% gelatin solution when all is said and done, and which you may find is easier to coat.

Make sure your emulsion is at 104. Also, add the alcohol and make sure you scrubbed the glass well.

The other thing to try that works: Keep the plate level when you pour the emulsion. Smear the emulsion around with your gloved finger to wet the whole surface, then roll the emulsion around.

Don’t do it the hard way just because someone else does.

[andrewch59]

Thanks for that info, will try another batch on the weekend.

[Nodda Duma]

Good luck. You’re 95% of the way there.