Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,659   Posts: 1,481,458   Online: 1073
      
Page 14 of 23 FirstFirst ... 4891011121314151617181920 ... LastLast
Results 131 to 140 of 225
  1. #131
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,707
    Images
    65
    I get a complete color kit from Michaels Art store for under $20.

    PE

  2. #132
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    Are you talking about a screen-printing kit Ron? I think that the Speedball Diazo sensitizer didn't work for Greg.

    Do you think Bud at the Formulary could get a hold of 4,4'-DIAZIDOSTILBENE-2,2'-DISULFONIC ACID DISODIUM SALT, CAS: 2718-90-3?
    If you are the big tree, we are the small axe

  3. #133

    Join Date
    Mar 2009
    Location
    Vancouver, WA USA
    Shooter
    35mm
    Posts
    298
    Wow...It's really been that long since I started this thread.

    It's been almost exactly a year since I got the diazidostilbene sodium sulfonate samples, but aside from the initial tests, haven't done much else with it. Need to get back to it.

    To get back to holmburgers' question: I only found 2 suppliers in the US, which you identified in Post 53

    Secant's pricing was better at the time, and I guess might still be. I've emailed you the pricing they sent me. I don't know how much demand there might be for a substance like this, especially with refrigeration being a storage requirement for long shelf life. Not sure the Formulary would be willing to stock it.

    Might be better off to try and organize a group buy across APUG/DPUG, the alt-photo list, LFF and the B&S forum. Might even get some advantageous pricing that way.

    --Greg

  4. #134
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,707
    Images
    65
    Quote Originally Posted by holmburgers View Post
    Are you talking about a screen-printing kit Ron? I think that the Speedball Diazo sensitizer didn't work for Greg.

    Do you think Bud at the Formulary could get a hold of 4,4'-DIAZIDOSTILBENE-2,2'-DISULFONIC ACID DISODIUM SALT, CAS: 2718-90-3?
    This is indeed a Speedball kit which I have not opened.

    As for Bud ordering chemicals, contact him. IDK.

    PE

  5. #135
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    Hey Greg, gosh, what a bad memory I have. However, I can't seem to find that email (but I do vaguely remember it). Any chance you still have it?

    At any rate I just emailed Secant. TCI comes out to $3.28/gram, sans shipping.

    A group buy would be a great idea, and I'd be willing to do some leg work to make that work. Let's see what pricing information we get back and I'll inquire about a larger quantity for a group buy. I will say, the price of this sensitizer compared to dichromate is kind of a bummer...

    If 1"² of carbon tissue requires 0.5mL (roughly), then 100 8x10" tissues would require 4L of glop, sensitized at 5% that comes to 200 grams at a cost of $656 (at $3.28/gram). The same sensitizing with potassium dichromate ($15.95/lb) would cost only $7.

    Tough sell...

    p.s. I'll send Bud a note.
    If you are the big tree, we are the small axe

  6. #136

    Join Date
    Mar 2009
    Location
    Vancouver, WA USA
    Shooter
    35mm
    Posts
    298
    2 quick points...

    1) Secant's pricing was way cheaper than TCI's @ 100 grams, and it gets even better if you order a kilo at a time. TCI's prices have gone up about 25% in the last year, it seems. Probably reasonable to expect that Secant's have as well.

    2) I believe CMB has pointed out (or it's in the data sheet he posted) that this chemical has a solubility limit at about 3% in water. And a lot of the water in glop is tied up in the gelatin. I think the guidelines he posted here show 1.5g of sensitizer per 250mL of glop. So for your hypothetical 4L of glop, it's only 24g, not 200.

    Dichromate will always be cheaper, but this makes the cost non-prohibitive.

    --Greg

  7. #137
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    Greg, thanks for making these points. I guess what I was (selectively) recalling was a comment from Mssr. Berger about using H#3 at a similar concentration to the dichromates. But if we can get usable material from concentrations around 0.6% then indeed, that's a great thing. Cuts our 100x price increase back down to about 10x.

    Also good to know that Secant's pricing will be cheaper. Hopefully they'll get back to me at some point soon.

    Now, Bud from PF got back to me asking a couple questions about theoretically obtaining this chemical, and I could use some help answering them.

    1 - What quantity would satisfy this initial experimental phase, for the few people who are interested?
    2 - What quantity would be alot and what quantity would be barely enough?
    If you are the big tree, we are the small axe

  8. #138
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,707
    Images
    65
    If you do buy in quantity, you must remember that the azo material is not stable and a large amount can go bad on you over time. So, if you need only 10 grams for a year, buying 1 kg for 10 people will give each 100 g of which 90 g might go bad.

    PE

  9. #139
    CMB
    CMB is offline

    Join Date
    Mar 2011
    Location
    Santa Cruz, CA
    Shooter
    Multi Format
    Posts
    84
    Quote Originally Posted by holmburgers View Post
    I was (selectively) recalling was a comment from Mssr. Berger about using H#3 at a similar concentration to the dichromates.
    To clarify:


    To tray sensitize pre-made carbon tissue in Hardener #3, try a concentration (typically 3%) and soak time similar to dichromate.


    To incorporate hardener #3 into a gelatin emulsion, 1.5 g/250 ml is a good place to start.


    Charles

  10. #140
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,400
    Images
    2
    Good point to note PE.

    Charles, thanks for clarifying this. Since an incorporated sensitizer is one of the most appealing aspects of diazo, it's nice to know that the required quantify is significantly lower, at about 0.6%. This puts things back into the cost-effective zone.

    I heard back from Secant, but nothing on a price yet. The nice gentleman who responded told me that this product was used in the manufactur of cathode-ray-tubes, I assume he meant the aperture masks, but he said that since this industry is more or less dead now, it's not manufactured on a large scale. They only have about 60 kg.

    I hope my comment, "well we'd probably be looking for 1kg or less..." didn't scare him off...
    If you are the big tree, we are the small axe



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin