First DCG, Please, Help me find the problem.

[Paulos]

One should be extremely cautious with such substances, as they act slyly.
In any case, work under a fume hood, use gloves, respiration and clothes protection.
If you cannot keep these precautions, it is better to leave DCG,
or to try Martin's alternative method with ferric salts instead of dichromate
http://holographyforum.org/phpBB2/viewt ... um+oxalate

Other than for not-carcinogenic poisons, where an exposure bellow a limit may be safe,
there aren't any safe exposure limits for carcinogenic substances.
The existing permissible exposure limits for carcinogens are simply legal, political compromises, to keep the damage as invisible as possible.
The only Cr6+ safety limit in the air, on your skin etc. is simply "ND", not detectable.
Roughly, if a long term "x" exposure to dichromates will cause "y" cancer cases inside a population, then a x/100exposure will cause y/100 cancers.
For a single person, that means that a lower exposure will reduce, but not eliminate the probability of a disease.

Although in general there are toxic doses, not toxic substances, this is not valid for the carcinogens, they are potentially lethal even in traces.

[Kiffdino]

Okay, i think ive undestood the considarable dangers of dichromate now.
I will take all the precautions i can.
But now lets get back to the initial topic of this post, which is after all me getting my first DCG hologram right using the G307 formula.
At the moment im busy but i guess next weekend ill be ready to do the next shoot.
This time neutralizing any remaining dichromate with metabisulfate. I promise.
Im happy now.

[Danny Bee]

Okay, i think ive undestood the considarable dangers of dichromate now.
I will take all the precautions i can.
But now lets get back to the initial topic of this post, which is after all me getting my first DCG hologram right using the G307 formula.
At the moment im busy but i guess next weekend ill be ready to do the next shoot.
This time neutralizing any remaining dichromate with metabisulfate. I promise.
Im happy now.

I agree so sorry this thread got so off track with adds to try "ferric salts" instead of Chrome.
have you tried the normal DCG process?
I feed that G307 formula is a bit too difficult for beginners,

[JohnFP]

He cannot get fixer in his country, thus his venture down the G307 road.

But as I suggested since he obtained SM. He might want to get some Alum and make his own fixer. That will get him to a nice base process that most DCGers are doing. Then if he needs to lower his exposure time he can revisit the G307 method.

KiffDino, can you get some Alum (aluminum sulfate)?

[Kiffdino]

i got the aluminum sulfate john, not that much though cause i only need 0.3 g everytime i mix the sensetizing solution for G307
but id be interested in the recipe for a homemade fixer...

i wonna try the G307 thing again though. just getting practice. This time considerably decreasing the distance between lens and object, by that increasing exposure energy. at the moment the distance is at 1.2meters.
and i will increase the baking time to 3 minutes. (last time 2 min) that should harden the emulsion enough to get that miklyness away.
for each alcohol beath i get a seperate airtight container, heating the last one with a therapeutic heating pad as you recomeded.

veil coating, sensetizing and drying went just perfect last time. So from the exposure on is where i got to improve.

cheerio

[Danny Bee]

He cannot get fixer in his country, thus his venture down the G307 road.

But as I suggested since he obtained SM. He might want to get some Alum and make his own fixer. That will get him to a nice base process that most DCGers are doing. Then if he needs to lower his exposure time he can revisit the G307 method.

KiffDino, can you get some Alum (aluminum sulfate)?

that sounds like good advice... what would he use as a hardener?

[JohnFP]

This time considerably decreasing the distance between lens and object, by that increasing exposure energy. at the moment the distance is at 1.2meters.
and i will increase the baking time to 3 minutes. (last time 2 min)

I wouldn't change baking time yet, as the increased exposue to light will add addition hardening and thus reducing the whitening. Maybe if you are still getting whitening after reducing the distance between object and lens then you can increase the baking time. Just a suggestion.

Home made Fixer.
It's difficult to say exactly because gel hardness, amount of AmDi in emulsion and exposure times etc... all play a roll. But as a a starting point I would start with 1 gram of Alum and 5 grams of SM per 500ml water. Then adjust the SM so all AmDi is converted (no more blue coming out) in about 1 minute. If it reduces to quickly reduce the amount of SM, if it takes to long to reduce increase the amount of SM. Then when you have that finalized. Adjust the Alum so your holograms are the brightest with no milkiness. If milky, then use more Alum, if brightness lacks and hologram is too narrow band then use less alum.

[JohnFP]

that sounds like good advice... what would he use as a hardener?

That would be the Alum I was asking him about.

[Kiffdino]

ahh ok, so fixer and baking are not canceling each other out. I see

alot of hardening going on:
the bloom of the gelatin ist the starting point with predefined hardness
then the alum in g307 is hardening
the exposure energy of the laser is hardening the gelatin
the baking is hardening
and now i would introduce a fixer for aditional hardening before the first washing bath?

[dave battin]

In case you'd still insist on using photographic fixer, why not take a look there (http://www.tetenal.com/index_c.htm?AKT= ... 00070&L=UK)?

Kiffdino, did you try martin's suggestion for the fixer?