Re: Ammonium vs potassium dichromate -- Bolte

Thanks, that's helpful. Do you also question their finding that
ammonium dichromate produces more insoluble PVA and that the reason
for this is that the ammonium cation is involved in crosslinking?

Katharine

On Apr 2, 2006, at 5:04 AM, martinm wrote:

> ----- Original Message -----
> From: "Katharine Thayer" <kthayer@pacifier.com>
> To: "alt photo" <alt-photo-process-l@sask.usask.ca>
> Sent: Saturday, April 01, 2006 7:15 PM
> Subject: Ammonium vs potassium dichromate -- Bolte
>
>
>
>> 1. How is it determined that holograms made with ammonium dichromate
>> are not as stable as those made with potassium dichromate.
>>
>> I don't know the basis for the statement that it has been "long
>> established that holograms formed from ammonium dichromate were of
>> better quality than holograms formed from potassium dichromate"
>> since I'm not working in the holographic field, but if it's a well-
>> known fact, it seems like it must be pretty self-evident. Perhaps
>> Martin could elucidate that for us.
>>
>
> I also wondered about their statement actually. The "long established"
> wisdom had been that at the previously relevant wavelengths for DCG
> holography (roughly 440 - 515nm, supplied by HeCd and Ar lasers
> mainly)
> ammonium dichromate provided much better speed than potassium
> dichromate.
> Incidentally, it may be interesting to note that pyridine
> dichromate was
> said to be
> the fastest among light sensitive chrome salts.
> Anyway, I don't think it's possible to establish any differences
> between am.
> dich./
> pot.dich. sensitized layers beyond speed or absorption to specific
> wavelengths. Speaking
> "of better quality" does not make sense in my opinion.
>
> Martin
>
>
Received on Sun Apr 2 08:23:09 2006