Helpful  Hints

The cost of instant pictures is outrageous and the results are not always satisfactory. If you are using this method to reduce your tracings you are throwing away a large part of your budget.

Assuming that your light source was constant and it was never necessary to change your speed or aperture settings, and waste film sheets trying for good contrast, the results are still second--rate.

Even the slightest gray background can darken your monitor and make it difficult to distinguish the cursor or breaks in the ridge lines, causing increased time when entering your tracings.

Try using a .07 lead (rather than . 05) and do your reductions on your copier. Without crowding your available copy space, reduce the 5:1 tracings by 50%, then reduce that reduction by 50%, and finally, reduce that reduction by 80%. This will return your enlargement to 1:1 at a tremendously lower price and produce tracings with, as near as possible, a pure white background.

Being a good little County employee, as I am, I hesitate to endorse a product (because it could get me in trouble). However, since there is only one of its kind I want to mention CRIMCON. If you are fortunate enough to have access to one of these great little contraptions, you can save a whole lot more, maybe enough to pay for the thing.

Capture/enlarge/print your latent in the mirror mode. Use a “Super fine Sharpie marker to trace the entire latent (at least the usable part) directly on the `photos', forget the miserable tracing paper! Turn the tracing face down on a light box and retrace on the super white back of the picture. In addition to the $2.50+ that you save per photo, this gives you a second chance at spacing the ridge lines and thereby eliminates time wasted rehabilitating the trace after the scan has created bifurcations in those places where your line wobbled too close to an adjacent ridge.

A large bonus in using the Sharpie is the constant width of the line, unlike a pencil which is always changing its shape and width (especially on recurves). Pencil lines tend to smudge when touched, a fast drying Sharpie doesn't.  And in case you need to change a line or get rid of a mistake you can erase the Sharpie ink very easily using an ordinary pencil eraser. The thermal paper texture is shiny and nearly non--porous.

The down side of the thermal paper lies in the fact that it is highly susceptible to heat. If you expose it to an incandescent desk lamp for too long a time it will be totally exposed and the image will be blacked out.

I have the necessary equipment and software to trace on my computer -- but time--wise it can't compete with the manual system I have described above.

I no longer buy or use Polaroid instant film sheets or tracing paper for latent print tracings.


Tom Jones
Latent Print Examiner
Kern Co. Sheriff's Dept.

This article was originally published in “THE PRINT”
Volume 12(5), September/October 1996, pg 11
and has been obtained from the online library provided by the

Southern California Association of Fingerprint Officers
www.scafo.org