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  1. #91
    kb3lms's Avatar
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    Test #2 - Much Better!

    After getting home from work today I ran Test #2 which (if you are following the saga) is that test strip that got the hardener and no photo-flo rinse. Here was the protocol:

    Ambient temp: 74 F
    Development: 10 min stock XTOL
    Wash/Stop: 1 min plain water
    Fix: 5 min

    Results: no frilling, no stripping and the gelatin in the treated area of the strip stayed put. Frilling was evident on the untreated part of the strip - which was to be expected. So now I have a controlled sample of one (lol) that has worked. Yay!

    PE, I can't check for fogging on this one because this strip was coated in the light. It was just easier that way. I will check on the next one though. But the DMAX is fantastic!

    Also, today, I ran across a relevant paper on prepping PET films doing a comparison of using NaOH and some sort of enzyme. Later tonight I will post either the paper or a link. It's from the fabric industry but the gist is that prepping PET in this way is a common practice.

    -- Jason

    PS: Has anyone tried to replicate my results?
    Last edited by kb3lms; 06-25-2012 at 06:19 PM. Click to view previous post history. Reason: Additional info posted
    All this has happened before, and all this will happen again.

  2. #92
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    Jason;

    If the enzyme is takamine, be very very careful. We used this under virtual hazmat conditions at EK to dissolve gelatin.

    PE

  3. #93
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    PE, that's not the enzyme. It's something else but I'm not going down that road anyway.

    Here's a link to the paper I found http://dl.dropbox.com/u/4212013/Surf..._stability.pdf

    It's entitled Surface structure and properties of poly-(ethylene terephthalate) hydrolyzed by alkali and cutinase, written by Ilaria Donelli, Giuliano Freddi, Vincent A. Nierstrasz, Paola Taddei, and published in a journal called Polymer Degradation and Stability. Hopefully anyone interested can open the link. Let me know if it doesn't work.

    Besides plenty of things I don't quite understand, there are two things of interest in this paper regarding the treatment of PET.

    1) A treatment protocol is given,

    For the alkaline treatment, PET films were immersed in a 1M NaOH aqueous solution at 40 C, for different times, from 30 min to 24 h, under agitation on a shaking bath (Isco SBH/D, 110 rpm/min). Afterwards, membranes were extensively washed with distilled water and dried at room temperature overnight.
    So here they tell us the concentration of NaOH, temperature and process. I am making the assumption that since these fellows are associated with the fabric and dye industry, they are citing a standard method of processing.

    2) The maximum necessary treatment time using the author's protocol is two hours,

    Interestingly, both NaOH and cutinase (the ezyme being compared Ed) lead to a levelling of the WCA values which do not change too much for treatment times longer than 2 h.
    WCA stands for water contact angle and refers to the amount of water beading displayed by the PET. The higher the WCA, the more beading. We want a low WCA.

    I am treating a new piece of Dura-lar now according to the information from this paper and I'll report back when I get some new results.

    -- Jason
    All this has happened before, and all this will happen again.

  4. #94
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    One Molar NaOH is 40 g/l. That is 4%. Very good luck to you. Looks good so far.

    PE

  5. #95
    kb3lms's Avatar
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    Some Observations

    Well, I'm back to write up some notes and observations. Maybe some of you can offer suggestions or at least it might help you to reproduce what I have done or go farther. A disclaimer here: I haven't yet used a 1M NaOH solution - the solution I'm using is 2.5M. Didn't have time to mix that up but it is on the docket. I did, however, run the current prep at about 100 F as mentioned in the paper cited above. I am running all tests right now with little bits of emulsion, but I am working on scaling up. My coating size right now would be about 6x7 cm. I have had two passing processing tests both after allowing the emulsion to harden overnight.

    1) Hydrophilicity (if that's a word) of the PET is greatly increased. After the NaOH immersion and washing, I hang the sheet to dry. It literally takes an hour for the sheet of PET to dry.

    2) Photo-Flo in the emulsion as a surfactant or in the PET wash (to avoid water spots - which probably doesn't matter) seems to be a disaster. Maybe the ingredients of the PF have a higher affinity for the PET than emulsion.

    3) Adhesion when coating at room temperature (70F) is great until slitting the film. After slitting, when looking at the back side of the film, you can see where the emulsion has separated from the support. If you pick at it with a fingernail or x-acto knife, you can separate the support and emulsion. However, if you do not pick at it, the coating seems to pass the processing test. Using chrome alum as a coating time hardener (1 drop 10% CA in ~5 ml emulsion) seems to make no difference. I think this is a mechanical effect where the PET is more flexible than the emulsion. As an after-thought, I've had this same problem when coating 3M base at too low a temperature and I believe others have mentioned this as well. Denise gave me a coating temperature of 32.5C (~90F). I believe PE has mentioned 100F in the past.

    Next actions:

    a) Try coating with support at 90 - 100F. This ought to reduce the viscosity of the emulsion and make it easier for it to grab onto the micro-pores in the PET.

    b) I have read in other postings about using ethanol as a surfactant. That's something else to try. QUESTION: Can IPA be used as a surfactant? I have lots of that. Everclear is NOT available in Pennsylvania but I am told I can use vodka.

    c) a "lights out" coating and exposure in camera. If I can get a coating close to 6x9cm, I plan to expose it in my Kodak Tourist. It's 1940s lenses probably don't have the UV blocking properties of newer lenses (just guessing here) and I also think this would be the easiest camera to use, now that it is back in commission.

    So some problems to work out but I've consistently gotten farther with the PET than other subbing methods I've tried. Oh, I also had a question of why not just use the 3M film or Melinex? Because I am looking for an inexpensive off-the-shelf solution and it's fun.

    Stay tuned,
    Jason
    All this has happened before, and all this will happen again.

  6. #96
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    Jason;

    IDK how you can coat at 70F. This is low enough for the gelatin to begin setting up. Usually, coatings are made at 100F. As for these coatings, the gelatin does indeed swell and shrink while the support does not do that very much. You can use alcohol instead of PF200, but you might try cutting down on the amount of PF. It is bad without but can be as bad with too much.

    Why not use the Melinx? Because the mfgr wants a minimum order of 8 master rolls of full width and length. This would impoverish everyone but Bill Gates or someone like him!

    PE

  7. #97
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    IDK how you can coat at 70F.
    I am thinking that has been my problem with coating all along. Now the gelatin itself is around 100F. It's heated in a kitchen shot glass that has a thick glass base that stays nice and warm for several minutes after taking out of the water bath. But the support and the glass I am coating on is room temp.

    The way I see it, the gelatin has got to be very fluid if it is going to flow into the micropores in the PET and grab onto it. Once the warm gelatin is poured onto the cooler base it would seem to me that a thin, high viscosity layer would form where the gelatin contacts the support and that would give poor adhesion. Make sense?

    I've tried heat up the workshop/darkroom to a proper coating temp but cannot get above above 75 F or so unless I would start a bonfire. The support is taped to a 1/4" thick piece of glass. Can I heat that up with a hair dryer or something? Would that work? What do other people do?

    I think I am missing something.
    All this has happened before, and all this will happen again.

  8. #98
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    Ok, I misunderstood. My darkroom is almost always at 70F and the plate I coat on is at ambient conditions or 70F. My melted emulsion and gelatin are at ~110F and my blade is at ~110F. I pour the emulsion or gelatin into the blade opening and coat. The mass of the blade maintains the melted material at above ambient conditions and the colder plate rapidly cools the substrate to about 70f. I then can hang it up to dry or leave it horizontal to dry.

    PE

  9. #99
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    I just got caught up on all the progress here after being outta town for a while. Great stuff that keeps getting better.

    I don't know if I'll be able to do any testing myself for a while, but in the future I definitely plan to. This appears to be a great discovery indeed!

    Ok, now as per your question over here, it seems clear that you need to have some kind of hardener in your emulsion if you want it to survive processing. Part of the workshop at GEH with Ron and Mark is to develop a coating that is unhardened and see what happens. Although my group didn't get around to doing, I understand that the result is an emulsion that nearly bubbles of the support, and that's on paper.

    I understand that a silver emulsion might act differently, but part of my interest in a simple PET subbing procedure like this would be for the making of DCG-imbibition matrices. Until sensitized and exposed, these coatings would consist simply of gelatin/sugar/dye.
    If you are the big tree, we are the small axe

  10. #100
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    Just a quick note about Grafix Dura-Lar Wet Media film. Last night I coated some sheets with 8.5% gelatin using both a 110-gapped Meyer rod and also a comb. So far, both coatings are sticking brilliantly to this surface.

    I also took two sheets and washed them thoroughly under water, hoping to get rid of any kind of subbing layer. I plan to coat these and I hope to see the emulsion peel off cleanly when dry. I'll also do a much thicker coating of pigmented gelatin on my last good sheet and see how it goes.

    But anyways, it's entirely possible that Grafix Dura-Lar Wet Media will work. Has anyone else had direct experience with this product? If so I'd love to hear your impressions.
    If you are the big tree, we are the small axe



 

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