by Steven » Fri Mar 02, 2018 6:41 am
"- Emulsion dripping down the wrong side of the glass
- Bubbles in the emulsion
Annoying parts of the process:
- The insane amount of excess emulsion required to coat plates, as much of it spills off in to the drip tray
- Having to constantly pour emulsion from drip tray back into squeeze bottle"
That is why I use dip and shoot.
I can coat my plates under normal lighting conditions, I don't worry about gelatin getting on the back of the plate,
if it does, I can clean it off under normal lighting. There is very little chemical waste and I don't need to worry about
getting emulsion back in a bottle. I only sensitize plates that have a good defect free coating.
AmDi consumption is very low.
I find that coating plates is the most difficult part of DCG, and is best done when you can see exactly what you are doing.
Everything else in DCG becomes a breeze, once you have done a few holograms.
The downside of dip and shoot, is that the surface of the emulsion is likely to pick up dust particles while it's drying,
but I expect the same problem using the veil coating method.
"Getting glass very clean and free of dust is tough without constantly replenishing your supply of distilled water or other solvent. I clean glass with Comet powder (amazing for cleaning things very well) then rinse with tap water. When I place the glass into a washing container, the liquid eventually gets too contaminated with minerals from tap water."
I stopped worrying about using tap water for cleaning the glass. Now I only use DI water for the gelatin coating and the last
water bath just before it goes into the first IPA bath.
My glass preparation method:
Cut glass to size and remove all sharp edges using a carborundum stone under running water.
Wash glass using using none scratch pad and washing up liquid. Dry and store the glass for when required.
Inspect glass and determine which surface is to be coated, if there is a scratch on the glass, that is the side that I will coat.
Using a carborundum stone and under running water, I put a small chamfer on the surface on one corner of the glass.
This helps to identify the surface I intend to coat during the cleaning process, right up to the actual coating.
Rinse glass under tap water and place in photographic tray face down.
I mix a very strong solution of Sodium Hydroxide and tap water, I also add a good squeeze of washing up liquid - take care
as the reaction of Sodium Hydroxide in water is exothermic. I only need about 60ml of this solution to clean two pieces
of glass, each 5" x 18". I use a none scratch scouring pad (no sponge) to clean the back of the plates, I then turn the plates
face up and clean that surface for a couple of minutes. I leave the plates like that for 20 mins or so before scrubbing again.
I do not flip the plates over to clean the backs, I just keep scrubbing the surface that I'm going to coat.
I do this for a few hours, scrub for a few minutes, leave for 20 minutes.
I thoroughly wash off all the Sodium Hydroxide under running tap water before placing them in Hydrochloric acid
face up (identified by the chamfer on the corner of the plate). The last time I checked the SG of the acid
it was about 9% HCl, so will need to add more water. I think that most of those using HCl to clean glass are using between
2% and 5% HCl.
After the glass plates have been in the acid for a few hours, I remove them from the acid bath (stored in the garage) and rinse
with a hose pipe before taking them into the house. I then rinse thoroughly under running tap water wearing surgical gloves
while rubbing the glass surface using my fingers. I used to rinse the glass after this with DI water, but lately, I haven't bothered.
I then dry the glass with tissues.
Steven.
"- Emulsion dripping down the wrong side of the glass
- Bubbles in the emulsion
Annoying parts of the process:
- The insane amount of excess emulsion required to coat plates, as much of it spills off in to the drip tray
- Having to constantly pour emulsion from drip tray back into squeeze bottle"
That is why I use dip and shoot.
I can coat my plates under normal lighting conditions, I don't worry about gelatin getting on the back of the plate,
if it does, I can clean it off under normal lighting. There is very little chemical waste and I don't need to worry about
getting emulsion back in a bottle. I only sensitize plates that have a good defect free coating.
AmDi consumption is very low.
I find that coating plates is the most difficult part of DCG, and is best done when you can see exactly what you are doing.
Everything else in DCG becomes a breeze, once you have done a few holograms.
The downside of dip and shoot, is that the surface of the emulsion is likely to pick up dust particles while it's drying,
but I expect the same problem using the veil coating method.
"Getting glass very clean and free of dust is tough without constantly replenishing your supply of distilled water or other solvent. I clean glass with Comet powder (amazing for cleaning things very well) then rinse with tap water. When I place the glass into a washing container, the liquid eventually gets too contaminated with minerals from tap water."
I stopped worrying about using tap water for cleaning the glass. Now I only use DI water for the gelatin coating and the last
water bath just before it goes into the first IPA bath.
My glass preparation method:
Cut glass to size and remove all sharp edges using a carborundum stone under running water.
Wash glass using using none scratch pad and washing up liquid. Dry and store the glass for when required.
Inspect glass and determine which surface is to be coated, if there is a scratch on the glass, that is the side that I will coat.
Using a carborundum stone and under running water, I put a small chamfer on the surface on one corner of the glass.
This helps to identify the surface I intend to coat during the cleaning process, right up to the actual coating.
Rinse glass under tap water and place in photographic tray face down.
I mix a very strong solution of Sodium Hydroxide and tap water, I also add a good squeeze of washing up liquid - take care
as the reaction of Sodium Hydroxide in water is exothermic. I only need about 60ml of this solution to clean two pieces
of glass, each 5" x 18". I use a none scratch scouring pad (no sponge) to clean the back of the plates, I then turn the plates
face up and clean that surface for a couple of minutes. I leave the plates like that for 20 mins or so before scrubbing again.
I do not flip the plates over to clean the backs, I just keep scrubbing the surface that I'm going to coat.
I do this for a few hours, scrub for a few minutes, leave for 20 minutes.
I thoroughly wash off all the Sodium Hydroxide under running tap water before placing them in Hydrochloric acid
face up (identified by the chamfer on the corner of the plate). The last time I checked the SG of the acid
it was about 9% HCl, so will need to add more water. I think that most of those using HCl to clean glass are using between
2% and 5% HCl.
After the glass plates have been in the acid for a few hours, I remove them from the acid bath (stored in the garage) and rinse
with a hose pipe before taking them into the house. I then rinse thoroughly under running tap water wearing surgical gloves
while rubbing the glass surface using my fingers. I used to rinse the glass after this with DI water, but lately, I haven't bothered.
I then dry the glass with tissues.
Steven.