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Photo Engineer
03-09-2011, 05:06 PM
Chris;

You have it right. The tolerance is 0.001" or 1 mil.

Tjaded;

I may end up in the funny farm!

PE

hrst
03-09-2011, 05:19 PM
I'm surprised that you can actually coat the final width directly with those, if I understood correctly.

I've been under the impression that you must leave some edges to be trimmed out. My blade leaves a millimeter or two of uneven coating at edges, and I need one centimeter or so for both sides so that the blade runs reliably on the film base.

Can you get usable coating edge-to-edge with those?

Photo Engineer
03-09-2011, 06:13 PM
Hrst;

Due to surface tension and other effects, the edges are always defective. This is called the selvedge. If you look closely at the support next to a film roll, you will see that the film is wider. The coater is also wider, but just right for the support. When you are done, you must trim the edges. I have to set up a trimmer for that.

In practice, Kodak coated 42" wide paper to get 40" of good coating. The edges were used for traction during movement through the machine and for the selvedge. The actual coating station was just over 40" wide. My 8" blade is 8.25" giving 0.25" of selvedge.

PE

Louis Nargi
03-09-2011, 09:47 PM
Interesting, don't understand this yet but will keep reading and learning.

polyglot
03-09-2011, 10:15 PM
I see now that the roll of acetate is about 5mm wider than a 120 roll, so that gives you some selvedge. However the blades look even wider than the roll, but they don't look like 8", more like a bit under 3". Are they going to work with this roll of acetate?

Kirk Keyes
03-10-2011, 12:49 AM
Sounds cool. Maybe make a section on 120 film making for Vol.2 of your book.

Kirk

Photo Engineer
03-10-2011, 09:57 AM
I see now that the roll of acetate is about 5mm wider than a 120 roll, so that gives you some selvedge. However the blades look even wider than the roll, but they don't look like 8", more like a bit under 3". Are they going to work with this roll of acetate?

Yes, it will work. I've already tested it in dry runs.

PE

jerry lebens
03-10-2011, 10:09 AM
Sounds like including the selvedge in the image might produce an interesting effect. How about coating some actual 120 size acetate and not trimming the edges..?

Regards
Jerry

Photo Engineer
03-10-2011, 10:12 AM
Jerry;

That is an interesting idea, but the selvedge makes the coating a tad overwidth by my measure, so it will have to be trimmed. In any case, it might just leave a black line down each side. IDK. I may try. This is months in the future.

Thanks.

PE

R Paul
03-12-2011, 11:37 AM
Hello PE

If you don't mind me asking, where did you get the acetate base? I am assuming that it isn't an off the shelf item.

Just think-- homemade 120 film -- I will start saving my backing papers now
rob

Photo Engineer
03-12-2011, 11:40 AM
This is not off-the-shelf, and IDK where I might get another roll. It was a sample given to me.

PE

kb3lms
03-13-2011, 06:27 PM
Hey, how about this "Plastic Cake Wrap" for acetate base? See the link below:

http://www.amazon.com/Plastic-Cake-Wraps-500-Foot-Roll/dp/B001AEMDL4/ref=pd_sbs_k_3

(If the link doesn't show correctly, I entered "acetate roll" at Amazon)

I admit to not knowing much about this but I know I had seen something like the roll of material in the picture and was able to find it again. It is available in several different widths and sheets also seem to be available.

The same sort of thing is listed at www.bakedeco.com. Google "cake wrap" or "cake collar" for more listings.

And if this is all out in left field, well... then "never mind." (think "Emily Latella" here)

Photo Engineer
03-13-2011, 07:16 PM
Probably left field!

The acetate must be subbed with a material that is "friendly" to the acetate and to the film, otherwise the emulsion will not stick.

Thanks anyhow.

PE

kb3lms
03-13-2011, 07:41 PM
LOL, there's always a a catch! I didn't think about that. What do you need to do for "subbing"? From your comments in the forums I guess it isn't something easy to do?

Photo Engineer
03-13-2011, 07:50 PM
I have a formula for subbing here somewhere. It involves organic solvents mixed with organic polymers and gelatin along with acetic acid. Basically, it is both hydrophobic and hydrophylic or you might say it has a bipolar disorder. :D

It does require a fume hood and lots of ventilation to coat.

Estar subbing is entirely different than Acetate subbing. Estar often requires electron bombardment to give it a tooth. See posts by HRST.

PE