Handcoating paper with coating blades

[Kirk Keyes]

Sandy - What's the price of the rods you linked to - they don't seem to want to publish pricing. I'm thinking like for something that would give a 5 inch or 8 inch usable area.

 

[Photo Engineer]

They are very messy and wasteful of emulsion. They are better than many other methods, quite accurate, but more difficult to control for absolute laydown. You have to build a well to prevent paper swell and other problems such as forming a "V" shaped defect at the head end of the sheet of paper. After seeing Mark use one, I decided that the Kodak method was more productive.

These work best with thick coatings, and those which do not cause severe variations with coating thickness. They also work well when the chemicals you are spreading are not expensive.

Mark Osterman and I have tried them out. Mark has several different types of these rods. Webster is an eastern suburb of Rochester where this company is located.

PE

 

[dwross]

http://www.thelightfarm.com/Map/PaperAndCoating/MapTopic.htm#PaperCoating

Denise Ross
www.thelightfarm.com

 

[Kirk Keyes]

"I'm sure Denise can fill in the gaps that I've left out..."

It looks like she already beat me to it with the link above!

 

[rmazzullo]

Hello PE,

Can you please tell me which alloy of stainless steel you were using for your coating blades?

Thanks,

Bob M.

 

[Photo Engineer]

308 or 316. Those are the best.

PE

 

[Photo Engineer]

http://www.thelightfarm.com/Map/PaperAndCoating/MapTopic.htm#PaperCoating

Denise Ross
www.thelightfarm.com

Good try.

Something similar to this was one of my first designs as noted in the OP.

There are problems with the tape wrapping wearing on the paper surface and causing uneven coating and there are also problems with leakage. I'm sure that they work well, but are high maintenance. I also feel that sensitizing dyes, hardeners and solvents may accumulate in the plastic. But, this is for the user to determine.

PE

 

[sanking]

I put down some fairly thin emulsions with the coating rod and despite Ron's caveats believe they would work. Of course, I always coat on a perfectly level surface, and wet out and squeegee the paper or plastic to be coated to a hard flat surface (galvanized steel or glass plate). In any event, there is very little waste in my procedure because I first spread the emulsion and then run the rod over the coating. The key to the way I work is that the rod is heated to a high temperature.

No idea how Mark Osterman works, only know him by reputation, but he may have the right rods and not use an appropriate procedure.

In any event, I definitely believe the rods are worth trying.'

Kirk, I have not ordered a rod from RD in several years, but they were quite inexpensive at the time. If they work you could waste a lot of emulsion before reaching the price of one of the speciality blades.

Sandy King

They are very messy and wasteful of emulsion. They are better than many other methods, quite accurate, but more difficult to control for absolute laydown. You have to build a well to prevent paper swell and other problems such as forming a "V" shaped defect at the head end of the sheet of paper. After seeing Mark use one, I decided that the Kodak method was more productive.

These work best with thick coatings, and those which do not cause severe variations with coating thickness. They also work well when the chemicals you are spreading are not expensive.

Mark Osterman and I have tried them out. Mark has several different types of these rods. Webster is an eastern suburb of Rochester where this company is located.

PE

 

[Photo Engineer]

I coat on a level and flat surface, with cold paper and hot emulsion. Well, see the OP for my description, it is all there.

The rod works, with quite a mess. I usually coat 0.005" - 0.007". When Sandy and I coated carbon, we coated 0.010" - 0.020". IDK what difference this makes. I don't remember what Mark used, and he is away giving a show in AZ.

I don't wish to argue the point as it may work. IDK. Beauty is in the eye of the beholder. I just know that Kodak Research has used the coating blade method for over 50 years, probably closer to 100 years by now . It works! It is hard for me to get low cost blades and is too much of a bother, but they do work. My blades, done in quantity, are probably 1/2 the cost of a one-off!

PE

 

[sanking]

Ron,

I don't wish to argue any point with you either. I merely suggested that the threaded rods may work and could be an affordable alternative to your blades. I am certain that the Kodak type blades work, after all you used them professionally for many years. But if there is no way to make those blades so that others can afford them it seems to me that other alternatives should be considered.

Sandy

I
I don't wish to argue the point as it may work. IDK. Beauty is in the eye of the beholder. I just know that Kodak Research has used the coating blade method for over 50 years, probably closer to 100 years by now . It works! It is hard for me to get low cost blades and is too much of a bother, but they do work. My blades, done in quantity, are probably 1/2 the cost of a one-off!

PE

 

[dwross]

Good try.

Something similar to this was one of my first designs as noted in the OP.

There are problems with the tape wrapping wearing on the paper surface and causing uneven coating and there are also problems with leakage. I'm sure that they work well, but are high maintenance. I also feel that sensitizing dyes, hardeners and solvents may accumulate in the plastic. But, this is for the user to determine.

PE

This helps me understand a statement in your OP. I was quite sure I remembered a conversation with you a couple of years ago where you said you'd never tried a glass emulsion metering system (i.e.'well'). It sounds like you tried out something made of plastic. There is no plastic in my system, unless you count the replaceable Mylar tape. Mylar film tape is almost indestructible and is precisely manufactured to thickness specs. I used a puddle pusher yesterday with a wrapping of tape that's been on it since before Christmas - and I coat paper or glass plates every other day. In point of fact, glass is extremely low maintenance. Without set screws and a separate blade assembly, a glass well is much easier and quicker to clean and dry between coatings.

I know you're trying to find a buyer for your emulsion blade plans, and I wish you all the very best luck with that. I loved your 4x5 blade until the set screws wore out. But, please be open to alternative ways of coating. There's no such thing as too many options. Sandy is spot-on about the cost issue, and different people will work best with different tools.

Don't forget your goal of selling books and DVD's. I suspect you could see a reasonable profit from those if people weren't afraid there wasn't going be a way to coat.

And, one more thing. The glass emulsion coating system is not a 'good try'. When I coat emulsion on the glossy baryta paper that Photographers' Formulary sells, it is indistinguishable from a commercial paper. And I can coat a small piece of paper or a piece up to 12" wide equally well.

d

 

[Photo Engineer]

Denise;

I am NOT looking for a buyer for the plans and I never have! I don't know where you got that idea. The schematics will be in the book. These plans were drawn up by one of my workshop students and he has given me permission to publish them. They are much better than my originals. In addition, my blades are in the hands of many people who can reproduce them from the original model if they wish. I have no reservations about that.

I am sure that your coating equipment works well. I just found what I had put together along those lines to be unsatisfatory for a variety of reasons. I have no problem cleaning and drying my blades between coatings. A quick dip in hot water, rinse, and dry with a towel! In fact, since the entire assembly is stainless steel, you can wash well at the end of a session and let the blade air dry.

As for many of our coating practices, well, they differ. To each his own. The blade method is most familiar and satisfactory to me as I learned using them at EK and we used at least 3 different models for paper and film along with what was used in production which was very similar. It has a long, successful history behind it that goes back to the early days of photography.

As for a "good try", well, yes your coating well is. The alternative is "bad try". I hope you see that this was meant to be a positive, not a negative statement. I am sorry you took it the opposite way. As I've repeatedly said, "if it works for you, use it!" and this holds true here as well for you and for your potential customers.

Sandy;

My comments in this thread are regarding coating on FB paper support only. IIRC, you used YUPO for coating. The rules differ when using YUPO, RC, Film and Glass as opposed to FB. If so, this explains some of our differences.

I agree that for your carbon coatings, this method is not optimum, nor is it cost effective. We aggred on that at the outset two years ago or so. OTOH, I found the rods to be messy and very cost ineffective for silver halide emulsions. They would be wonderful for albumen, carbon and a number of other processes, but very expensive for Pt/Pd for example.

All;

This thread was meant to determine the extent of my coverage of paper coating, centering on using coating blades such as I was trained with. I wanted to see if I had touched all bases. I had not intended to create a debate on who's method is better or worse, nor do I wish to here. I have found that some methods did not suit me and this was based on years of practical work in the lab and the work of many who designed equipment at EK for this type of work. That is the reason that I settled on this method.

I have film blades from 120 size up to paper blades of 16" width. I have seen photos at Kodak of equipment like this that coats up to 40" wide on film and paper both, and also a similar method for glass plates.

My statements here are not meant to imply that any other method is poorly designed or faulty. You will have to determine that for yourself, just as I did several years ago.

PE

 

[sanking]

Ron,

I did not suggest the threaded rods based on my experience with coating carbon tissue. For that I don't use a threaded rod but a plain rod which I roll over flexible magnetic sheeting material which determines the thickness of the coating. And my carbon coatings are quite thick, with wet height up to 1.5mm.

However, I have used threaded rods to apply thin gelatin emulssions (8-10%) to paper for sizing, and I have also used the rod to make POP paper, which also contained gelatin and a silver solution. In both cases I was able to get even coatings, though like everything else it takes practice to use the rod efficiently. By efficiently I mean getting an even coating while keeping as much of the solution as possible on the paper to avoid mess and waste. If you use an oversize piece of paper there is very little mess as it is relatively easy to keep all of the solution on the paper. I always pre-wet the paper and squeegee it to the coating surface to keep it flat while coating.

Pre-wetting may or may not be appropriate for coating your type of emulsions, I don't know. I merely suggested the use of the threaded coating rod as a possible alternative to the blades because the rods are relatively inexpensive and available in a wide range of thread depths so if someone were interested in experimenting with them they could do so for a relatively small expenditure.

Sandy

 

[Photo Engineer]

Sandy;

I understand fully. That is the reason for the last paragraph in my post above. Each person should determine the suitibility of the coaitng methhod(s) they choose.

And yes, the carbon tissue is so thick that it can hardly be called tissue. It does not work well with the coating blades, but it can work. It is just not cost effective.

I have worked with both wetted and dry sheets of paper. Either can work, but the wetted sheets are more cumbersome in the lab and take longer to dry. I can't say as it was worse though, just more time consuming for the same result in the cases I tested. We always used dry paper at EK.

PE

 

[rmazzullo]

Hello PE,

Do you know if there a clear picture, (or pictures) of the stainless steel coating blade from different sides that might have been posted on APUG, or perhaps elsewhere?

Thanks,

Bob M.

 

[Photo Engineer]

I have posted one before Bob, along with a disassembled blade and a picture of blades of different types. I will eventually post the full drawings as well. I have no interest in commercialization of these at all and never did really, just an interest to get them out there and to recoup the initial investment.

I hate to take up more storage space on APUG, but if you cannot find a satisfactory example, let me know and I will repost the (digital) photo again.

PE