> Tom Ferguson wrote:
> ...
> > Standard Bostick and Sullivan chemicals, grade 5, half platinum, half
> > palladium, on Cranes Platinotype paper.
> ...
> Clearing was three 5 minute
> baths in EDTA (3 teaspoons per liter of water).
> ...
> > The problem with testing, is it always seems to show you something you
> > didn't expect. Someone in this thread (Jeff ?) said that developing the
> > paper with tape on it (to avoid getting chemicals on a section of the
> > paper) was not only a way to test for safelight fogging, but if you
> > developed a piece that hadn't been exposed to any light, it was a way to
> > test if your clearing was complete. Unexposed paper in my situation does
> > show a very slight "stain", compared to the "virgin" paper under the tape.
> > I tried doubling my clearing time (three 10 minute baths), without any
> > change.
>
> Tom,
> May I suggest you try the following to clear prints on Craines
> platinotype paper.
>
> A) place print in tap water for at least 5 minutes. (maybe 10)
Tom and Jeff
If your prints are hard to clear, I would recommend that in place of tap
water, you use distilled or purified water for at least the first clearing
bath. This should help eliminate the solids that are building up in the
paper reacting with the iron. (Does your clearing bath get cloudy? or just
brown/yellow in color?)
Try this test.
Add a small amount of rinse from your coating devise , brush or rod, to
some of your "tap" water. If it clouds ups, you should consider using
distilled water for at least your first, and perhaps second clearing
baths. You should notice that your prints clear much easier.
> B) place print through three 10 minute baths of H3PO4 (phosphoric acid,
> reagent grade from chemical supplier), mixed 2 ounces acid in 1 gallon
> water. I find that H3PO4 works best for clearing.
> C) wash
>
Citric Acid also works well, at a 5% to 10% solution.
Also try Kodak's Hypo Clearing Agent (Mostly EDTA) as a last step. Very
useful to help your paper clear.
> or for step B:
> B) place print through three 10 minute baths of HCl (hydrocloric acid),
> mix 3 ounces of 20% muriatic acid (not the kind for swimming pools for
> it has additives, but the kind found in hardware stores for etching
> concrete.) into 1 gallon water.
>
> EDTA DOES NOT CLEAR FOR ME. I have tried it, it does not clear. IT
> DOES NOT WORK FOR ME. I do not want to hear from Richard Sullivan, it
> does not work FOR ME.
>
What type of EDTA are you trying to clear with. Tetra? Di?
> Note: If you omit the tap water bath, I find that the B&S Crains
> business card stock (special run) (what you call platinotype) takes an
> hour to clear. For some magical, yet unknown reason the tap water bath
> cuts the clearing time in about half. Try the test again and let me
> know. I get no decernable stain when clearing this way.
>
> Note: Other papers will clear differently with different times.
>
EJ Neilsen
ejnasn@laplaza.org