BVDA: How to use Hungarian Red

Gellifters 1, 2

Hungarian Red

1,2-Indanedione

Labeling of dangerous substances and preparations

Latex set

5-Methylthioninhydrin

Narcotest

Phosphatesmo KM

ThermaNin

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How to use Hungarian Red

On what surfaces can it be used

Hungarian Red is a dye solution in water/acetic acid mixture that is used for staining fingerprints and footprints made in blood. Prints in blood are colored red after treatment with Hungarian red. Hungarian Red should not be used on absorbing surfaces like paper, carton, bed sheets, carpet etc. It works very well on non-absorbing backgrounds like linoleum, glass, tiles, painted surfaces and PVC floor covering.

Fix prints in blood before staining

Before staining, prints in blood should be fixed to prevent them from running (causing loss of detail) when the staining solution is applied. This is a general procedure that should be used with any staining solution (with the exception of Leuco Crystal Violet, where fixative is present in the solution itself).

How to fix the prints

Fixing is best done with a 2% solution of sulfosalicylic acid in water (20 gram in 1 liter). To make sure the print in blood is thoroughly fixed, it is recommended to make use of absorbing paper like filter paper, tissue paper or paper towels which are wetted with the sulfosalicylic acid solution.

Part of a shoeprint in blood, stained with Hungarian Red

Take a dry piece of paper and put one edge next to the print, while holding it over the print. Then wet the edge of paper with the fixative so that it will stay in place. Then starting from this edge, wet the paper progressively further, while smoothing the wetted part on the print and minimizing trapped air bubbles. This procedure can be done the easiest when the fixative is applied with a wash bottle. When this is possible (for example with an object or with a print on an angled surface) start from the top and work downwards.

Once the wet paper is on the print, leave it there for a minimum of three minutes. When the blood is a thick layer, leave it there longer (5 minutes or more). After that, remove the paper. An excess of fixative can be rinsed away with water, but this is not necessary.

When the blood has not aged too much, you will notice that the blood changed color, from dark red to dark brown.

Staining procedure

Now that the print is fixed, it can be stained with Hungarian Red. The most economical way is using the sprayer. Spraying always causes some mist (aerosol) that will float around in the air. Especially when you stain large areas, do use some respiration protection. Alternatively, you can use a wash bottle (or with fingerprints even a disposable pipet).

After having applied the staining solution by sprayer or wash bottle, leave it in contact with the print for about one minute. Then rinse the surface with water (or a 5% water/acetic acid mixture = 19:1 volume/volume ratio). If the print is located on a floor, the wash water might be removed with a vacuum cleaner that can handle water. Otherwise you need to resort to paper towels or the like to remove it.

It is advantageous to immediately remove the water and water droplets from the processed area after rinsing, with compressed air or a powerful blower. If water droplets remain on the print, you will notice that some dye will dissolve in them. After drying that will be visible (possible loss of detail).

Lifting and fluorescence

Hungarian Red not only has a good staining capacity, it also has some special characteristics. Stained prints can be lifted with a white BVDA gelatin lifter so that backgrounds are eliminated and/or parts on dark backgrounds become visible. The lifted print will also fluoresce, whereby details or prints that were hardly visible with the naked eye are now easily discernible in fluorescence.

Before lifting with a white BVDA gelatin lifter, the area should be completely dry. Be very careful not to trap air bubbles under the lifter surface and leave the lifter on for 15-30 minutes. Photograph within a couple of hours after lifting (the dye will slowly diffuse in and across the surface of the lifter, thereby blurring the print).

Lifting can be done more than once, with or without re-staining in between lifts and should be tried in important cases where you suspect this might help.

Fluorescence is excited with green light (515-560 nm) and the filter used in front of the lens is a red filter (Kodak Wratten 25, a barrier filter of about 600 nm or a long-pass filter with cut-on of about 600 nm).

Safety

Hungarian Red is not labelled as a hazardous preparation. Since it is water based, no harmful fumes are liberated in use, although the acetic acid smell might be irritating. It will color the skin, although this will not last very long (in our experience less than a day). Contaminated clothing will be stain-free after regular washing.

Hungarian Red-stained part of a shoeprint, lifted with a white gelatin lifter, fluoresces under green light

Sulfosalicylic acid crystals are labelled as an irritant substance, the 2% solution is not labeled as a hazardous product. Given the fixative effect on blood, we do advice strongly to use gloves (vinyl gloves will suffice) when using it.

Avoid breathing aerosols (mists) of both the fixative and Hungarian Red. Also avoid contact with solutions and wash your hands after work and before breaks.