I'm So Blue

[JohnFP]

I got it John, thanks. But if I use, let's say (stupidly ) 4 grams of AmDi and 28 grams of gelatin in 100ml of water and said I am using a 14% AmDi to gelatin wouldn't I get some funky monkey results ?

Well not really, you would get results exactly consistant with a 14% sensitizer in your emulsion. But due to the low ratio of water and gelatin you would need tape (spacers) for the mold coating process to be about 1/2 mil (25 microns) to get that 8 micron thick coating. Whereas doubling the water to 200ml will allow you to use the 1 mil (50 microns) tape for a final 8 microns thick coating.

The water is used to determine thickness and has nothing to do with the final emulsion properties because we are always trying for about a 7 micron thickness (give or take a little). Agian, usually water is only changed to compensate for your coating technique. The AmDi to Gelatin determines absorbtion rate, mass loss in final gelatin, amount of light that passes through to object, exposure time, fixing time, etc...

[Danny Bee]

go to this link http://www.lasart.com/jewelry/index.html he uses 2-5 microns
i was able to get about 7microns in the casting method using 7-8/100ml and with 1% or lower chrom
when using tape as spacer and heating your cast plate and your glass plate it come out very faint yellow alowing alot of light to go thro the plate

[Martin]

The water is used to determine thickness and has nothing to do with the final emulsion properties because we are always trying for about a 7 micron thickness (give or take a little). Agian, usually water is only changed to compensate for your coating technique.

I think this is not entirely accurate, John. The gelatin/water ratio may well have an impact on the rigidity of the gel for example.

By the way, in order to standardize your DCG formulas, one thing to not forget is the type of gelatin...

[Dutchelm05]

7-8/100ml and with 1% or lower chrom

Is that 1% total or about 1 gram or

1% of AmDi and Gel or .7 grams Danny?

[Danny Bee]

7-8/100ml and with 1% or lower chrom

Is that 1% total or about 1 gram or

1% of AmDi and Gel or .7 grams Danny?

7 to 8 grams of knox ... sorry my brain works faster than i can type..and some times i skip things

[JohnFP]

I think this is not entirely accurate, John. The gelatin/water ratio may well have an impact on the rigidity of the gel for example.

How would the amount of water in the solution change the rigidity of the gel when it has been cured/dried to a specific final water content? Wouldn't 5 g of gel to 100ml of water have the same final properties as 5g of gel in 500ml of water when both were allowed to cure to 13% water content, provided you coated the latter 5 times thicker?

By the way, in order to standardize your DCG formulas, one thing to not forget is the type of gelatin...

Yes sir, right on. Not only type but manufacturer, bloom and batch.

Martin, I will have to confess that altering water contect does change things and thank you for pointing this out. I was trying to make the point of how we should think about and discuss AmDi concentation and was purposely subjective.

Second hand effects of changing water content and then compensation for it with emulsion thickness surely will have an effect on drying time and ulitmately the amount of time dark reaction can take place. It also plays a role in the ease of handlabliliy of the emulsion during the coating process. And I am sure we can think of more.

But I tend to believe that changing just the water contect 10 or 20% to accommodate your coating technique will not significantly change the properites of the final dried/cured emulsion.

[Danny Bee]

I think this is not entirely accurate, John. The gelatin/water ratio may well have an impact on the rigidity of the gel for example.

How would the amount of water in the solution change the rigidity of the gel when it has been cured/dried to a specific final water content? Wouldn't 5 g of gel to 100ml of water have the same final properties as 5g of gel in 500ml of water when both were allowed to cure to 13% water content, provided you coated the latter 5 times thicker?

By the way, in order to standardize your DCG formulas, one thing to not forget is the type of gelatin...

Yes sir, right on. Not only type but manufacturer, bloom and batch.

Martin, I will have to confess that altering water contect does change things and thank you for pointing this out. I was trying to make the point of how we should think about and discuss AmDi concentation and was purposely subjective.

Second hand effects of changing water content and then compensation for it with emulsion thickness surely will have an effect on drying time and ulitmately the amount of time dark reaction can take place. It also plays a role in the ease of handlabliliy of the emulsion during the coating process. And I am sure we can think of more.

But I tend to believe that changing just the water contect 10 or 20% to accommodate your coating technique will not significantly change the properites of the final dried/cured emulsion.

this thread is getting long .... in talking about water john in the casting sytem i think you can only go down to about 7 microns...... and because the gel is so thin it doesnt need as much aging time

[JohnFP]

So what if, it's getting long. Isn't that what the forum is for? To discuss back and forth?

Why can't you go below 7um? Does the film not hold together well enough when pulling the plates apart at thinner coatings?

[Danny Bee]

So what if, it's getting long. Isn't that what the forum is for? To discuss back and forth?

Why can't you go below 7um? Does the film not hold together well enough when pulling the plates apart at thinner coatings?

i wasn't complaining yes they dont hold to together well enough ..... now i wonder if the mix is aged in a bottle for a week or so if you could go lower?.... or use something else as spacers

[Martin]

How would the amount of water in the solution change the rigidity of the gel when it has been cured/dried to a specific final water content? Wouldn't 5 g of gel to 100ml of water have the same final properties as 5g of gel in 500ml of water when both were allowed to cure to 13% water content, provided you coated the latter 5 times thicker?

My point is that that the dried layers made from those two solutions may differ considerably - on a molecular level.
I can't really say what's taking place there in detail – hopefully Jeff will return to the forum some say. Maybe one key thing is the drying process which greatly affects the nature of the final layer. Obviously, under identical environmental climate conditions the two gel solutions you mentioned above, will dry differently.

Yet another thing may be cooling/freezing a gelatin layer, which may actually sort of crosslink the layer.

I've seen a couple of old (1930s) articles by some of the famous Kodak people like S.E. Sheppard. They did a series of systematic studies on “The structure of gelatin sols and gels” (I think most of their work used to be accessible through the Internet).
Moreover, one of those Stojanoff papers I already pointed to (http://holographyforum.org/phpBB2/viewt ... f=5&t=5272) puts strong emphasis on the importance of the drying conditions (prior to the holographic exposure!). This seems paramount towards standardization and high efficiency.

By the way, in order to standardize your DCG formulas, one thing to not forget is the type of gelatin...

Yes sir, right on. Not only type but manufacturer, bloom and batch.

Absolutely - since what's called "gelatin" may actually greatly differ from one type to another.