HOW TO... make fingerprint stamps for metal clay

We were recently asked how to make fingerprint stamps. The kind of stamp that can be pressed into metal clay. Here are some stampmaker tips to help you create them.

Taking the impression

1. Inkless wipes
The way the image appears undoubtedly has wow factor and there’s no risk of little inky fingers marks where they shouldn’t be. You should be aware that the liquid contains phthalates. It will take fine impressions if done correctly, however it can over expose the paper from over-wetting or pressing too long and it is expensive to use.

2. Lipstick
Crème based lipstick can take nice fingerprints. It is a readily available in all households. You do need to obtain non-streaky and even coverage on the finger first.

3. Ink pads
This is the traditional way for police forces across the world to take prints and is cheap and very effective. You will find the second impression is often clearer as the first can over-ink and lose detail.

Scanning it
When you scan the image optimise the Brightness and Contrast to achieve maximum contrast and make the paper white rather than grey.

Converting it
You can use any software program to convert to black and white, such as Photoshop or Corel. Alternatively, load the image into the imagepac program, with fingerprints it is almost always the case that you should modify the brightness and contrast to optimise the strength of black and the white.
Printing it
All inkjet printers will print black enough to use as a negative. To optimise the printer setting print a small black box out using the different print options provided in the shortcut menu and check against a light to see which is blackest. The best option is likely to be changing the paper setting to photo paper matte or cardstock (an absorbent paper only requires a lot of ink).

Exposing it
Make sure that you cover the entire area of the base of the clamp with either your negative or opaque material such as card.

Correct exposure times:
Use 10 seconds and 30 seconds

Standard exposure times for Stampmaker are 6 seconds and 100 seconds, but for fingerprints (as with photographs) you need to increase the first time to 10 seconds. This will build a solid, thick floor and allow just a quick second exposure through the negative that will hold the fine fingerprint detail without filling it in. Flip it over and expose through the negative for just 30 secs. The stamp will be soft, but wash it thoroughly and harden it under lights as usual.

You can experiment with the second time, but the longer you leave it in the closer together the fingerprint lines will become, the shorter the time the wider they will be and the deeper the depth of relief, but beware as the lighter or more isolated parts may fall off.

Pressing into clay You can press the stamp in by attaching to an acrylic rod (clear so you can see where you see where you are pressing), you can lie it on top and roll it down or our preferred method- attaching it to the back of a tea spoon with double sided tape and pressing it in as a convex surface.
The spoon will take on the curvature of the stamp and in the process slightly open the fingerprint lines. This makes the impression look more life-like.

Let us know how you get on with it, and by all means post your fingerprint projects!