Technical Note

Vacu-Box Instruction Manual

Vacu-Box Safety Information

• Keep the unit dry and clean
  
• Read all of the instructions before using
  
• Electric shock can occur if used improperly
  

Description of Equipment

• Electrostatic Vacuum Box
  • Dimensions: 39 x 35 x 17.0 cm (approximately 15 1/8" x 13 3/4" x 6 3/4")
  • Weight: 10 kg (22 lbs.)
• Roll of Type IW film, 40 cm x 100 meters (approximately 15 3/4" x 328')
• Adhesive film, 24 sheets, 25 x 35 cm (approximately 9 3/4" x 13 3/4")
• Corona Unit
• Developing Powder, 75 grams
• Developing Brush

Background
In criminal cases where documents are present, e. g., drug transactions, kidnap notes, bank hold-up notes, forged checks, etc., handwriting may be present which is not visible under normal conditions. There may have been writing which was done on a piece of paper which left indentations in the document in custody. The procedure in the past was to use oblique lighting to photograph any indented writing which may appear. This process was not always successful.

A solution to this problem is to use electrostatic energy and black powder. The document is placed on a vacuum plate, covered with a sheet of plastic film, and charged with electricity. A special black powder is brushed over the surface. The high-voltage electric charge will cause the black powder to collect in the indentations, making the writing easy to see and easy to photograph. Because the original document is covered with plastic, it is not damaged or altered. The image of indented writing can be saved by placing an adhesive cover sheet on the plastic film.

Directions for Operation - Indented Writing

	1) Place the document face up on top of the vacuum plate. Use tweezers to handle the document to prevent your fingerprints from developing.
	2) Cover the document and vacuum plate with the Type IW plastic film. Turn on the fan to create a vacuum. Using a cotton ball or a small piece of cloth, smooth the film over the document to eliminate any wrinkles or air gaps. When the film is smooth, switch on the vacuum pump and cut off the film from the roll.
	3) Turn on the Corona switch. Holding the Corona unit about one-half inch above the document, pass it back and forth over the film for 10 to 15 seconds. Keep the center of the Corona unit over the document.
	4) Using the developing brush, gently apply the developing powder to the plastic film. Brush back and forth (side to side and top to bottom), applying powder as necessary to develop each word. HINT: Use the least amount of powder necessary to develop the image. Practice and experience will guide you. When you see partial text, concentrate on that area and use more powder on that area, if necessary.
	5) To save the visible indented writing, cover the plastic film with an adhesive sheet. Start the adhesive film at one end of the film to cover it. Or allow the adhesive sheet to sag and stick to the middle of the film to cover it from the middle to the edges. For good adhesion, rub the surface with a roller. There will be no damage to the original document. Turn off the vacuum pump.

Helpful Hints

• If the paper evidence is also going to be examined for latent prints, perform the indented writing development first. Processes like Ninhydrin or Physical Developer are wet processes which will destroy indented writing.

• When applying the developer powder to the film in indented writing recovery, apply it in long stokes, first side to side, then top to bottom. Apply small amounts of powder. More can be added. Too much cannot be taken away easily.

• Only the center of the Corona unit is active. Use the center of the Corona unit to charge the film and paper. When passing the Corona unit over the film, it is easy to miss the edges and corners of paper, so be certain that the active area of the Corona unit passes over the entire surface of the paper. Do not set the Corona unit down on top of the film and paper while processing, as it will produce a dark area of powder if using it for indented writing.

• If too much powder is used and it seems that some writing is "overdeveloped," just start over with a new piece of IW film. The document is never damaged or altered.

Photography Tips

• For photography of indented writing, a medium-contrast to high-contrast film should be used. Do not use color films, as they do not show contrast as well as black-and-white films.

• While small-format film in 35mm cameras can be used, medium- to large-format cameras are recommended. The Polaroid MP-4 or MP-4 Plus or other style of copy stand large-format film cameras use 4 x 5 sheet film and have methods for controlling the amount and direction of the light.

Care and Maintenance

• Keep the powder from being drawn into the vacuum.

• Do not touch the wire inside the Corona Unit. It is very fragile and can break.

Replacement Supplies

Catalog No. 4-5527 Type IW film, 100 m roll
Catalog No. 4-5528 Developing Powder, 75 g
Catalog No. 4-5529 Adhesive Sheets, 25 sheets
Catalog No. 1-0035 Developing Brush

© 1995 Lightning Powder Company, Inc., Salem, Oregon, USA
Prepared by Kathleen D. Saviers, CLPE, CSCSAB