Substrates for Shooting in Camera - FILM, Acetate, PET (polyester), Glass, etc.

[Mustafa Umut Sarac]

Thank you Chris to heads up.

 

[kb3lms]

Thanks Chris and Umut. Looks interesting. Does anyone have access to the full article? There are also some patents that refer to the same sort of idea. Would it be likely to work with sodium hydroxide as well? The first page mentions polycarbonate as well as PET. I've got a whole roll of polycarbonate film to experiment with. I'd figured out a way to sub it but it didn't come out looking very nice and wasn't as flexible as when I started.

Then again, I haven't made much of a dent in the support Denise sent me. :-(

 

[Photo Engineer]

Sodium Hydroxide would be as good as Potassium Hydroxide but you may need a bit more of the Na salt to adjust for molecular weight and for the very tiny decrease in alkalinity of the Na.

PE

 

[holmburgers]

Ron, do you recall if you or Jim B. ever came upon methods for subbing PET? I remember that you mentioned researching this a bit in the past and I believe the answer was no. So, is this an epiphany, or something that perhaps you've deemed impractical?

Just curious; I'm gonna shoot Jim an email too.

 

[Photo Engineer]

I really don't know what Jim tried. I don't think that he did any subbing experiments. I feel that if this were commercially feasible, then someone would have reduced it to practice, but I have never heard of it being used. Technically, it should work, but it may be impractical from some POV.

PE

 

[holmburgers]

Thanks Ron; I'll report what Jim responds with.

I'm also interested in "flaming" methods of hydrophillisizing (is that a word?) PET. An inline blow-torch perhaps? Could be fun!

 

[hrst]

AFAIK, flaming is quite difficult to control and is prone to deforming the material. It has been almost completely abandoned decades or half a century ago for corona treatment. I would use that effort to try your luck with corona which is very simple in theory. Still, the only real problem is sourcing the suitable transformers for low price.

 

[Photo Engineer]

Have you ever thought of just running a blank sheet of Estar through a Xerographic machine? That may give it enough of a charge.

PE

 

[hrst]

Haven't tried but it probably won't work, because what I found out is that it's not the charge but the quickly toggling charge that causes the surface treatment. Therefore, DC did nothing but just gave the static charge. It needs to be high-frequency AC.

 

[kb3lms]

The idea of etching PET with an alkali metal hydroxide seems common enough in the patent literature and there is also mention of resin coating and, of course, corona discharge. The corona discharge method appears to be considered the state of the art for maybe the past 20 or so years, likely because it may be more controllable and easily able to be done as an in-line process step without chemicals.

Tonight, I did try a quick experiment with a 10% solution of sodium hydroxide in water, which brings the first problem: PET is hydrophobic so the solution runs right off. (duh!) What's an appropriate solvent for the NaOH? Perhaps ethanol or methanol? Would a wetting agent like photo-flo help? There were some references to ethylene glycol as a solvent as well.

-- Jason

 

[hrst]

The success of the experiment is easy to check quickly by sprinkling water on the sheet. As you say, it runs off on raw polyester, but if the treatment is successful, then it will spread nicely, as I show here: http://www.youtube.com/watch?v=StgbV766dqQ .

 

[Mustafa Umut Sarac]

Jason,

Put film in to chemical bath not chemical on to film. May be this would be a solution.

Umut

 

[dwross]

hrst,

Thanks for bumping your youtube here. It is just about the best geek-cool thing on the internet. The time stamp on it this morning gave me double-take whiplash, though. Has it really been a year and a half ago since you did that experiment? I'll be really happy when you get time to get back to the emulsion lab!

***************
Umet,

There really isn't a reason to go with PET over acetate except for how flat ester films still are after they are subbed. Acetate subs easily and cheaply and relatively safely, at least compared to some to the ideas floated here to sub polyester. The problem with it is that the subbing chemistry/process causes it to wrinkle. You almost have to flatten subbed acetate with heat before coating. Coating thickness is only ~ 7-15 mils and so by default the surface topography tolerance of the film is very, very narrow.

Any chemical that can etch polyester film is likely to cause an uneven surface. Same, of course, for heat. This pretty much defeats the reason for using polyester film. Corona discharge treatment doesn't last long, and can fog emulsion, so (as I understand it from my conversations with Dupont) you want to sub the PET with something hydrophilic immediately after the discharge treatment. Then, that subbing lasts a long time and is emulsion-friendly.

Anyway, what I'm getting at the long way round, is that if the goal is a diy subbed film, readily at hand for an intended project, think subbed acetate. Do you have a project in mind that requires PET?

d

 

[kb3lms]

Umut,

Yes, I agree. Later last night I found some notes on an industrial application of the etching process and that was what was done. I have some PET from a vegetable container soaking in a small container of alkali now.

-- Jason

 

[rmazzullo]

When I spoke to these folks some years ago, they told me they could supply a clear acetate film leader with a subbing layer or a clear polyester leader as described on their web site (link below). If I remenber correctly, different options available (subbed, different widths, additional layers, etc) were also discussed, but I was primarily asking about the acetate, not the polyester.

Their web page is at: http://www.filmotec.de/?cat=27&lang=en&lang=en
The pdf for the material I was looking at back then: http://www.filmotec.de/wp-content/uploads/2010/08/V-I-TI-LF3S-e.pdf

Since the leader is normally supplied in 35 and 16 mm widths, both perforated and non-perforated, you will have to open a dialog with the sales agent at Filmotec to find out what options are available. Back in 2008, the sales manager's e-mail was Frank Böhme, and his e-mail address was "bohme@filmotec.de" (no quotes).

Bob M.

 

[kb3lms]

The success of the experiment is easy to check quickly by sprinkling water on the sheet. As you say, it runs off on raw polyester, but if the treatment is successful, then it will spread nicely...

So here's some early results. This is using pieces of PET cut out of discarded food containers. For both tests, half the piece of PET was treated and half not.

1) Sheet wiped with NaOH solution. No noticeable difference in water runoff test. A slightly sticky feel when running your finger across the treated area but the effect doesn't last. Does not look like a viable route.

2) Overnight soak in NaOH. Water spreads over the treated area and does not run off. Still runs off as expected in untreated area. Treated part of the PET has a cloudy appearance. You can still easily see through it, but it's not as clear as the untreated part.

Next step I think will be to make a test strip with progressively longer "soaks" in the NaOH and water test. See if I can identify a lower limit on the soak time required.

-- Jason

 

[dwross]

Umut,

Apologies for misspelling your name earlier. If it's any excuse, half the time I type 'densie' for my own and only about half those times manage to catch it.

d

 

[Mustafa Umut Sarac]

Denise ,

you cant believe how many mistakes I was writing to bill of ladings at shipping company I never been able to learn typing with 10 fingers. I was using a letters deleted keyboard until last month and I was going insane

Umut

 

[Mustafa Umut Sarac]

Jason,

Great and quickly made experiment that we dont see frequently at APUG.

Good luck ,

Umut

 

[holmburgers]

Great and quickly made experiment that we dont see frequently at APUG.

Ditto.

The result sounds pretty interesting, and just a little bit encouraging... no?

 

[Mustafa Umut Sarac]

yes , it is.

 

[kb3lms]

Well, I am back with some results and I think they are very encouraging.

Here are the test conditions,
Temp: 70 F
Solution: 20 ml NaOH 25% solution in distilled water
UUT: 2.5 inch x 1/2 inch strip of PET, approx 12 mils cut from a food container (cherry tomatoes if it matters)

Procedure: Using a kitchen shot glass, 1/2 of the PET strip was dipped in the NaOH solution and evaluated at 5 minute intervals up to 30 minutes with the exposed part of the PET serving as control. A further check was made at 60 minutes and a final at 6 hours (360 minutes). At the end of each interval the strip was rinsed in clean water and dried. Clarity and wettability (is that a word?) was evaluated against the untreated portion of the strip.

Results:
Clarity: The clarity of the strip did not show a noticeable change throughout the test. It appears a clarity change takes longer than 6 hours.

Wettability: At 0 minutes, wettability was nil. Water dropped onto the strip beaded and ran right off. At 5 minutes, wettability was clearly improved although there was still significant beading. At each 5 minute interval wettability improved up to 30 minutes. However, there was still (but much less) beading even at 60 minutes. Wettabilty might have been acceptable for coating at 60 minutes, though. (Had to leave home for some other business at this point.) Last check at 6 hour point: Beading was nil at this point and water dropped on the PET strip spread into a smooth layer. While wettability might continue to improve, the strip compared favorably to the overnight sample, without the cloudiness.

The NaOH is granular lye drain cleaner from the hardware store. It's reputed to be quite pure. The ingredients are listed as 100% NaOH.

At this point, I believe you would want a 6 hour soak in the NaOH to prepare PET for subbing. While higher temperature might reduce the soak time, I think we can see why this wouldn't compare well to corona discharge for an industrial process. But for home brewing, if we're just making a few feet at a time, I see no reason why this method could not be used.

Any chance someone else can try this to see if the results can be repeated? I do not have any unsubbed PET film on hand. If anyone has some could they give it a try? I am thinking about getting a small roll of Graphix Dura-Lar but I don't think I'd be able to get to it before next week.

(Wow, I love this stuff!)

-- Jason

 

[Newt_on_Swings]

Has anyone hear heard of transparent aluminum?

http://dornob.com/transparent-aluminum-glass-like-see-through-metal/?ref=search

 

[holmburgers]

Jason, what a bang up job you've done. This is great stuff!

I'd love to know how it works with gelatin. I could send you some of the photoformulary melinex, which on one side is basically raw polyester and the other side a subbing that should wash off. Maybe Greg would send you some of his Grafix Dura-lar, mentioned earlier??

Any idea if this treatment has a 'shelf-life'?

 

[Photo Engineer]

Has anyone hear heard of transparent aluminum?

http://dornob.com/transparent-aluminum-glass-like-see-through-metal/?ref=search

AKA Aluminum Silicate, AKA Gorilla glass.

Corning wanted to use the name Transparent Aluminum, but it was copyright by Paramount.

PE