Make your own clear rubber stamps (polymer actually) to use on clay, polymer clay, fabric, paper, or anything else you can think of. This is an easy process that allows you to make stamps out of practically any black and white image you can come up with, and you can make them whatever size you like. They are also much less expensive than commercial rubber stamps. About 25 cents a square inch.

Step 1: Gather All Your Equipment and Supplies

The process of making a polymer stamp is a fairly straightforward, once you know the basics. Simply put, Photopolymer is a liquid polymer that is reactive to UV light and will harden when exposed. Knowing this, a negative can be made that allows the UV light to show through only where the stamp image is to be. The negative and polymer is exposed and the excess polymer washed away, leaving your custom rubber stamp.
There are two pieces of equipment that you will need to make to expose your rubber stamps, although both are very simple to make. The first is the UV exposure light. If you think you might be doing a lot of rubber stamp making I would invest in a fluorescent light fixture with UV (black light) bulbs to fit. You will need to attach two 6 â x 6â wood boards to the side of the light to raise it 4â off of the table surface. Some light fixtures will need to have a cord attached, which can easily be done by cutting a 6â extension cords female end off and direct wiring to the fixture. To make the light fixture easy to use a on/off switch may be wired to the light as well to make turning off the light between exposures easier. Another solution for those who donât want to wire their light fixture is to simply purchase a clamp light and hang it 4 inches from the tabletop. They come with cords attached and a turn of button on the top of the fixture. You can purchase a flood style black light bulb to fit the fixture.
The second piece of equipment is the glass exposure plates. These are simply two matching sheets of 8 â x 8â single pain clear glass , with the edges wrapped in electrical tape to keep your hands clear of sharp edges. Along two parallel edges of the taped plates lay magnetic tape on both sides. This will hold the plates together and keep them from shifting during the exposure process.

Materials
Light Fixture and UV Bulb
Developer Plates
Digital Timer (must measure seconds)
Photopolymer
Washout Solution
Substrate Film
Damming tape
Transparency Film
Two containers to hold liquid
Gentle scrub or tooth brush
Baby powder, Cornstarch, or talc
Optional
Clear acrylic or Plexiglass for mounting stamps
Pink erasor

Step 2: Design the Negative

The first step in making a polymer stamp is to create the negative. This will allow UV light only to penetrate the polymer where you choose. To create the negative, first either select or draw a black and white image that has bold lines or shapes. The reason for this is fine lines do not survive the washout process well, and will not make a strong impression in clay. If you are only looking to use your stamp like a traditional rubber stamp you can get away with having finer detail on the stamp. Your image must be strong black and white contrast, no grayscale or shading. Once you have your image you need to translate that into a negative. That means making the black parts white and the white parts black. This is easily done in most graphics programs, and it is usually listed as an “invert colors” command. You can also design you image in negative format by hand if that appeals to you more, although it is a much more time consuming process.

Step 3: Print the Negative

The final step in creating the image is translating the image to transparency film (the type used for overhead projectors) which can be purchased from any office supply store. If you are creating your image by hand then you will need to paint the negative space of your design with opaque paint. Paint pens work very well for this. If you are going to print your negative from a computer, make sure you use Laser Transparency Film in a laser printer of the negative will not be opaque enough to block the excess light. If you try to use regular transparency film in a laser printer you will melt the film to the print head, a very expensive mistake.

Step 4: Setting Up for Exposure

Once the negative is created, you can start to prepare the exposure unit. It is a good idea to have everything laid out and ready because the photopolymer is light reactive, and will set up quickly one exposed, even to ambient light. Place the light fixture on a level surface covered in butcher paper, or vinyl tablecloth to protect the surface. In one of the liquid containers, add two cups warm water and 1 tbsp. washout concentrate and set aside. In the other shallow container add 1 inch of cool water, and set aside. Cut the negative out of the larger sheet leaving at least 1/2 inch black border around the edge of the image. Place the negative down on the inside cover of one half of the glass sheets at surround the image with damming tape, leaving small gaps at any edges to let excess photopolymer to ease out of the edges. Trim a piece of substrate to the same size and the negative and set aside.

Step 5: Exposing the Image

With this preparation done you can now proceed with the exposure process. Pour liquid photopolymer gently onto the negative, filling the space up to the level of the damming tape. If there are any bubbles, quickly but careful pop them with a needle tool. Place the substrate, frosted side down, on the photopolymer, making sure there are no bubbles trapped under it or the stamp will peel off later. Place the other side of the glass unit on, making sure the magnets take hold. You may notice some seepage from the edges of the negative as the glass compresses. This is normal.
Place the unit centered under the light, substrate side up, and set the timer for approx. 1 minute 30 seconds. (exact developing times will vary from light to light, experiment on some smaller stamps to get the exact times dialed in for you). Turn on the light and develop for the required time. This develops the backing of the stamp. Turn the unit over and develop for the same amount of time on the other side, and turn off the light.

Step 6: Washing Out the Stamp

It is now time to start the washout process. Immediately separate the two halves of the glass and peel the negative off of the polymer. Always peel the negative off the polymer not the substrate off or the stamp will not have a good backing for washout. Place the polymer image in the washout solution and gently scrub with fine bristle brush or soft toothbrush until all of the excess liquid polymer is dissolved from the stamp surface. Rinse in water to remove the last of the washout solution. At this time you can trim off the excess hardened polymer. Place the stamp in the plain water container and set under the UV light and expose for 10 minutes. This fully hardens the stamp, and makes it less tacky.

Step 7: Final Conditioning

There are two ways to condition your finished stamp, depending on what you intend to use it for. If you use your stamp to make impressions in soft clay then simply dust your stamp with talc or baby powder to separate it from the clay, and keep it from getting tacky. If you intend to ink you stamp use a pink eraser to rough up the surface of the image. This allows the ink to stick to the stamp long enough to make the image. Your stamp is now ready to use and enjoy.