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[quote="manalokos"]The cooling seems to have no efffect, I think it wasmainly because of the high
concentration of AmDi that makes the gelatine melt.[/quote]

So you really must have a very low Bloom gelatin.
Another thing to try would be a diluted ethanol (or isopropanol) - water + dichromate for sensitization, maybe a 50% alcohol solution would be good for a start. I don't know how long this solution remains stable though (assuming that it takes an acid to oxidize the alcohol).

Hello Martin

The cooling seems to have no efffect, I think it wasmainly because of the high
concentration of AmDi that makes the gelatine melt.

Alum does the trick for me, but it must be carefully dosed so it will not overharden the plates.

Best regards
Filipe

[quote="manalokos"]The ones dipped in bath without alum took much more time to dry and slightly melted, the result was more broadband
and a bit milky, I still can't find a way to avoid melting without using alum in the solution... [/quote]

Cooling your sensitizing bath to 10°C or so might help.

Hello

Today I received my new laser from Dave, a coherent sapphire 488-20,
and was able to test it on some new dip-n-shoot plates I made with Knox gelatine,
I had to order Knox from the U.S.A. because I can't find it in Portugal...
This gelatine is much much harder than the one I used before so I have to recalibrate
my developing variables.

Here are some first light holograms, these are small 3x5cm. and made exposures
between 30 and 60 seconds. probably I am overexposing, but still I didn't get them
as bright as I wish they could be as I need to tweak the gel hardness.
[attachment=0]hb.jpg[/attachment]

The ones dipped in bath without alum took much more time to dry and slightly melted, the result was more broadband
and a bit milky, I still can't find a way to avoid melting without using alum in the solution...
[attachment=1]cwu.jpg[/attachment]

my plates are very yellow, that might also have contributed to reduce the object/reference ratio
and reduce brightness.

Thank you Dave for all your good advice!

Here is one clock made with my previews batch of plates with much softer gelatine and much longer exposure:
[attachment=2]clockx.jpg[/attachment]

Best regards
Filipe Alves