my first ones!

dave battin · Post by **dave battin** » Mon Jun 04, 2007 10:50 am

d paul wrote:Hi Dave

Does mold coating work for silver halide as well as MBDCG? Right now, I’m trying to get a piece of granite for a bigger (3x5) table. Prices are ok, but getting over there is tough.

be sure to tell the stone yard you will accept a "ugly" pieces of granite as this will greatly reduce your price.

as far as mold coating is concerned its best to use a piece of 1/4" thick rear surface mirror as your mold, it will be flat enough .......

to see results look in the gallery at Cristiano_Perrucci's MBDCG holograms (done with mold coat method)

Glass is very cheap, I purchase old framed pictures at the salvation army!

Be careful you want only flat plate glass, I lay the glass on the floor and look at the reflected image of the ceiling, now move your head side to side and you should see NO distortion in the reflected image, if the glass is bad, you will see it right away

d paul · Post by **d paul** » Tue Jun 05, 2007 12:30 am

Hi Dave

I kept the glass doors from an entertainment system we threw out . They are tempered and seem to fit the bill. I also check out the salavtion army store; that's where I got a BIG glass table top for like 25 bucks.

The stone place starts at 6 bucks a square foot (the other quote I got was 45/sqft) I can't wait to tell them it doesn't matter what it looks like , because i'm gonna spray paint it black

I subbed the plates today, so probally this weekend I'll run them off.

rob

dave battin · Post by **dave battin** » Tue Jun 05, 2007 9:26 am

Be careful using tempered glass as its been fired to relieve stress and tends to have turned edges, look for this in your reflection ......... good luck rob

Hans · Post by **Hans** » Tue Jun 05, 2007 9:47 am

Hans, can you write up a short description of your interferomic measuring set up for gelatin thickness?

It's already there: http://holographyforum.org/phpBB2/viewt ... 1558#41558

I use the Project Star Spectrometer. This is a truly remarkable tool for the holographer because also the quality of the safe lights can be quickly and visually inspected with it.

d paul · Post by **d paul** » Mon Jun 11, 2007 11:42 am

Hans wrote:
Does mold coating work for silver halide as well as MBDCG?
It sure does. But, although mold coating creates very smooth surfaces, the thickness of the gelatin will vary with the curvature of the glass (unless you use very flat glass, which is hard to find). DCG and MBDCG are much more forgiving with respect to gelatin thickness than pre-mixed silver emulsions. As far as I know, the diffusion method is also forgiving to gelatin thickness because the depth of the AgBr crystals depends on diffusion time rather than gelatin thickness.

I got the most even thickness with a 2% gelatin solution and some wetting agent added. Then take a piece of glass and stick one layer of Scotch tape to the sides, thus creating something to hold a puddle. Then pour the emulsion onto the glass (glass mut be very horizontal) and spread it even with a bar. Then allow to gel and dry. With an interferometric test I measured a thickness of 7um with variation of maximum 1um across the plate.

Dear Hans

I have run off a series of plates using different methods. Your method went well,as did spinning the plates after coating, but the mold coated plates may be a bust. Even overnight the plates were coming up all sticky.

I pulled a couple off the glass this morning, and I will see what they look like in the evening when I sensitize the others

rob

dave battin · Post by **dave battin** » Mon Jun 11, 2007 9:22 pm

d paul wrote: the mold coated plates may be a bust. Even overnight the plates were coming up all sticky.
rob

rob how long did you refrigerate your plates for? the drying time seems to be extended when mold coating (i usually wait at least 4 hours befor use...)

d paul · Post by **d paul** » Tue Jun 12, 2007 10:30 am

Dear Dave

Ididn't refrigerate them at all. When I made the MBDCG plates, they came off the plate perfectly at 3 hours or so without cooling ,so I thought it would work the same here(guess not).

I used 15g/100ml gelatin fot the MBDCG plates, and 4g/100ml for the silver halides, so this is a factor to be reckoned with.

At worst I can park the glass support on a tray of ice and see if that works.

First results have been disappointing, but will see today how they stack up

rob

vacuum · Post by **vacuum** » Sun Jun 24, 2007 4:17 pm

what are your ideas about glass coating method?

d paul · Post by **d paul** » Mon Aug 06, 2007 10:39 am

so far what's worked for me with silver halide is using a meyer bar to coat the plates,and then spinning them to even the coat out. For mbdcg I mold coat the plates

rob

Colin Kaminski · Post by **Colin Kaminski** » Mon Aug 06, 2007 2:19 pm

vacuum wrote:what are your ideas about glass coating method?

I can't find this link but I think you are looking at a vacuum machine that is designed to make thin film coatings on glass like AR coatings. It is not what is used for gelatin. I believe large film manufactures use a spray method. For some small run ides look here:

http://www.holographyforum.org/HoloWiki ... ng_Methods