Veil Coating (with Spin or Lean)
Veil Coating - Part I
The glass can be coated at room temperature or warmed up to the temperature of the emulsion (110 - 120°F.). The warmer the glass is, the thinner the final emulsion thickness will be. A great starting point is room temperature glass (70°F.) Take a cleaned glass plate and blow it off with a shot of canned air to remove any dust particles. Hold the glass with one hand at a 45° angle over a heated excess tray. Use gloves. You can use a therapeutic heating pad to keep your tray warm. This keeps the emulsion from hardening in the excess tray. Slowly pour the emulsion up the left side of the plate about ¼ inch from the edge, then across the top and down the right hand side. If this is done correctly you will notice a nice even flow across the plate when you are pouring across the top. Then take a ¼ sheet of paper towel and ball it up and wipe about a ¼ inch of emulsion from the bottom edge of the plate in one continuous motion.
Post Spinning - Part IIa
Take the plate and immediately place it on a turn table and spin it as 78 RPM. An old phonograph works great and has been used for years by many holographers. Let this spin for 10 minutes. A helpful suggestion is to make a rack that can hold plates horizontally on the spinner but leave a nice air space between the plates so they can dry evenly. Then one can coat and spin many plates at a time only stopping the spinner momentarily to quickly load the next freshly coated plate. I have found that spinning longer is better and I allow my plates to spin for at least 10 minutes after the last plate has been loaded into the spinner.
Post Leaning/Lying - Part IIb
If a spinner is not available then lean the plate against a wall in a tray that can be use to catch the excess for thinner emulsions or lay the plate flat and horizontally for a thicker coating.
Re-Using Emulsion - Part III
If you run out of emulsion in the pouring container while coating, just pour the warmed excess back into the pouring container keeping the pouring container at an angle so as not to cause any bubbles. Allow the emulsion to come back up to coating temperature of 110 to 120°F. After the plates are coated the excess emulsion can be poured back into the container and stored in the refrigerator for a later coating session. I have found the emulsion will keep for weeks this way. Although refilter does not have to be done during one session if things are kept clean, I suggest refiltering after refrigerating and re-cooking.
Dave Battin's Article on Veil Coating
Having tried all the methods available to most hobby holographers, I've found the best method for me is the veil coat method. I have attached a still shot to give you a preview to this method, and I plan on showing a step by step instructions so all should be able to coat easily. please see the video clip at the bottom of this page to see this method in action, sorry for the weird color ,as im actually making DCG film under a yellow/red safelite
The size of the glass is 4"x16" if i trim off one inch the top it will yield me Three nice 4x5s.
When acquiring glass I have found a great source is at your local art store, the type that has a special every week, (here its called Michael's), Its the replacement glass sold for picture frames, located in or near the framing department. It comes cleaned sealed and slightly lighter/weight than the regular 1/8" glass found at the local hardware store. The largest I can get is 16"x20" for @ $5 each, not bad for coming cleaned and ready to cut .................. subbing will be next
I have found it much easier to cut the glass into 4”x16” pieces before subbing.
A simple jig to cut your glass will give you nice consistent cuts every time. By banking your glass to the stop and placing the proper width spacer on top, simply bank your glass cutter against the spacer and slice. It’s best to provide a little lubricant to help the cut a little (I lick the cutter first).
Now that my glass is cut, I'll prep the surface for coating.
This glass is pretty clean already. If you’re unsure, I would soak it in a 20% Clorox Solution (soak over night), and after a quick water wash, soak in the Cascade (dishwasher soap) and water mix (I use a small handful for 2 gallons of water or so) again soak overnight after a slight scrubbing action using a plastic scrubby pad.
After removal of the glass from the Cascade, I give it a quick dip into clean water and then a final plunge into what they refer to as (Trisodium Phosphate) substitute. Where I live, they won’t allow the use of the real TSP, as it’s bad for the ground water. Allow to dry by leaning on wall, sitting on a paper towel.
The glass is now ready to be coated, but we must add a few extra items to make things easier later on …………………………
Well, the glass is almost ready to coat.
We will have to attach a few pieces of tape and paper to make this work correctly.
I do all the work under my laminar flow booth.
It helps to place your plate (the glass will now be referred to as plate) on some type of pedestal (as shown) or block of wood. (photo A)
Start by placing the plate face down on the pedestal and applying plain old ordinary scotch tape to both long sides of plate, adhere tape directly to the back of the plate, allowing only half of the tape to hang off the sides the entire length of the plate (photo B). I call these gutters. These will allow you to coat your plate up to the very edge without any waste.
Once the gutters are in place, turn your plate face up, and again place on the pedestal. Now using a short piece of tape slightly longer than the width of your plate, attach it to the top, adhering directly onto the face of the plate, again leaving half the tape to hang off the top (photo C).
Now that the top tape is adhered, we will now apply the “Tab”, a small 1x5 inch piece of paper applied from the back of the plate stuck to the tape along the top. This tab will be used numerous times throughout the operation so be sure its adhered well (photo D).
Your plate should now look like this:
The paper tab I attached to the top of the plate, will now act as a handle and I can hold it while doing a final cleaning, I lay the glass across my leg and wipe it clean (front only)using a folded paper towel and simple Windex glass cleaner ,always spray on the towel and not the glass!
With my method of coating I felt to lean is to be constant! The angle of incline is not so important, but its to always repeat the same angle, I achieve this by placing the plate in a holding jig, see the video to help explain, the film is now ready for coating .
A few minuets after coating , the paper tab will now allow you to attach a large paper clip, and hang your film to dry. By using a lab base and thin rod clamped horizontally, its easy to hang 12 4x5s to dry!
The blow dryer I use is old and weak! But it has two settings hi/low heat, at low it is very weak (blowing), and you will see me blowing close to the wet emulsion. Most new blow dryers will be way to powerful for this.
To apply the emulsion I use a simple squirt bottle, very easy to regulate flow, with the current bottle, I can coat three 4x16 plate before I have to recharge the bottle.