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  1. #41
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    Heavy particles do reach the surface of the earth. The energy is quite high.

    Try here: http://www.sciencenews.org/search/se...nd_submit=Find

    They ran a recent article on Cosmic Rays and discuss the various particles, energies and the penetration of the earths atmosphere and magnetosphere.

    Over time, enough reach the earth to begin fogging film. There is a lengthy thread on this and the amount and type of metal needed to afford protection. I suggest that rather than duplicate this thread here, you look up that old thread.

    Lots of good stuff there.

    PE

  2. #42

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    Quote Originally Posted by EdSawyer View Post
    dslater: that ebay link is a CP-51, the bigger brother of CP-31. i have one of those too, though not set up currently. That one is not what I would consider complete. You really would want the W/D unit too which is 2 more baths plus a dryer. You could make do with the one picture but would need separate wash and dry stations (manually). CP-51 will do 20" wide paper, cp-31 will do 12" wide paper. CP-51 requires 240v power also. (CP-31 is 110v). Baths on CP-31 are 2L, baths on CP-51 are 6L. I use the Cp-31 a lot and find it a good managable unit with reasonable size limits. I have the full Cp-51 setup too, but I haven't the space or power configured for it yet, though someday I will get around to that.

    Pricewise I think you might be able to do better also. I got my Cp-51 with W/D unit for $250, it needs major cleaning but it is complete and working. (Shipping was $400). I picked up my first CP-31 in mint shape, with W/D unit, and replenisher from a university for $300 total. I bought a second CP-31, also complete as mentioned (though not nearly as clean) for $100. New these setups ranged from $12-20k. There's several other CP-31/51 users here on Apug, some good info in the past messages... worth a search.

    thanks
    -Ed
    Thanks for the info Ed. I'll keep my eye out for a Cp-31.
    Emancipate yourselves from mental slavery;None but ourselves can free our minds. - Bob Marley

  3. #43

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    would a slight yellowish cast be improved by a final rinse incorporating optical brighteners? I've done this with older b&w paper where the base had become off-white, and the results were impressive. However, that was a case of a yellowed base, not yellow base fog.

  4. #44
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    The developer and the paper base itself contain brighteners, but this is offset by a UV absorber.

    PE

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