Assembling a Rubber Stamp Blank

A complete rubber stamp is an assembly of three layers of material: a layer of rubber bonded to a layer of soft, squishy foam, which in turn is bonded to a rigid backing.  When used, the stamping pressure applied should be distributed uniformly across the area of the stamp by the rigid backing, and the soft foam should compress slightly to ensure that the entire surface of the rubber is brought into contact with the paper.

Sometimes you can find ready-made 3-layer blank rubber stamps in a crafts store.  They look just like the many pre-made stamps available and are usually in there somewhere on the same rack, but instead of a cute picture on the top they have either a solid black rectangle or circle or some text reminding you to carve a mirror image.  Buying one of these items would obviously save you the time and effort of assembling your own.  The cost is usually more than you would spend making your own, though.  There is also a question of durability; Speedy-Stamp, MasterCarve and PZ Kut are known to hold up well inside a letterbox in the wilderness, but the durability of the commercially-made blanks under such conditions is unknown at this point.

I normally choose my artwork before assembling my stamp blank so that I can assemble a stamp blank that is precisely the correct size for the artwork.  However, it's also acceptable to turn this idea around, make the stamp blank first, and then select and size artwork to fit it.  You can even just make blanks that are too big, although this obviously wastes materials and also results in big, clunky stamps when smaller, more compact ones would work.

The first step is cutting out a piece of rubber to a suitable size and shape with a razor knife (a boxcutter will also work).  Leave at least 1/8" of rubber beyond any edge of the design; this gives you some tolerance for lining things up when you apply the image, and it improves rubber stamp durability bouncing around in a letterbox in the woods or wherever.  You can just cut out a big rectangle, or you can try to be more thrifty with the rubber and just cut right around the outline of the image itself.

Here's a convenient way to do this:  If the image is on the computer, print it on a piece of card stock or cover stock.  Using a straightedge, draw a polygon around the image, remembering to never get closer than 1/8" to any part of the image.  Then cut out this polygon with scissors or a paper slicer.  Lay the card stock polygon on the rubber and mark all around it with a pen or pencil, then cut out the rubber along the outline marked.

Cut out a piece of foam the same size and shape as the rubber, or perhaps a little bigger.

Cut out your wood or backing material to fit the foam.  If your rubber and foam is some oddball shape and size, you'll probably choose to make the wood a simple rectangle or circle.   Remember that just because your computer prints out an image in a particular orientation on paper doesn't mean you must align the rectangular stamp that way.  Sometimes you can rotate the rectangle to some other position that allows you to fit the entire image within a smaller rectangle.
Aligning the stamp with the image

Use contact cement to bond the foam to the backing material, and then glue the rubber to the foam.  I suggest that order because gluing the foam to the backing piece first will hold the foam flat while you're gluing the rubber to it.  For those not familiar with contact cement, you apply it to both surfaces, allow it to dry until tacky, and then put the parts together.  If you put them together while it's still wet, they won't bond.  They also won't bond if you wait too long, the stuff dries beyond tacky to simply inert.  With most contact cements such as the standard Weldwood, the optimum drying time is about 15 minutes.

If you're using peel-and-stick foam pipe insulating tape for the foam layer, you don't need to apply contact cement to that side.  Apply the contact cement to the mating surface, allow it to dry, and then peel and stick the foam tape to it.

An alternative idea to the contact cement:  If you stop by your local auto parts store, you can pick up a can of Permatex "Heavy Duty Headliner & Carpet Adhesive".  This is contact cement that comes in a spray can.  It is formulated for automobile headliners, which means it can handle being left in a parking lot on a hot sunny day without coming apart.  I find this stuff is preferable to the standard bottle of Weldwood contact cement with the brush in the cap for a couple of reasons.  For one thing, the glue in the spray can never dries out, you can leave it on the shelf for five years and it's still good as new.  For another, it's actually cheaper to use, especially if you consider how much glue you can use from the little bottle before you have to throw it out with a bunch of dried-up glue in the bottom that the brush can't reach.

If you can't find the Permatex product, 3M "Super Trim Adhesive", part no. 08090 is the same thing except it costs twice as much -- but it's probably easier to find.  Note:  There might be cans of 3M "Trim Adhesive", part no. 08088, right next to it on the shelf.  Don't get that stuff, it's not as good as the "Super Trim Adhesive".

To use the spray glue, spray it on the surfaces you intend to glue -- right in the middle.  If you aim at the edges, you're gonna miss and get glue everywhere.  Spray a blob right in the middle, then use a Q-tip or toothpick to spread it around.  It's thinner than the stuff in the little bottle, so it spreads better.

Note:  The spray glue doesn't seem to work too well on Dollar Tree erasers.  Apparently there's something in the rubber that dissolves the glue.  You would be well advised to try some other type of glue with those erasers.

One alternative to contact cement is Perfect Glue #1 by Liquid Nails.  It works very well, and many people like that it has essentially no odor.  The only downside is a longer drying time; in fact, you'll probably want to assemble your stamp blank and let it sit overnight before carving.  The cap that comes on the tube of Perfect Glue #1 is poor and often cracks resulting in the entire tube drying up and needing to be discarded, so some opt to seal the tube with a piece of plastic wrap instead.

I once suggested the use of poster tape, the white foam stuff that's sticky on both sides, for use on small stamps where such thin foam might be acceptable.  However, I have found that the adhesive on the poster tape is not really durable enough for this job, and seems to turn into a gooey mess after a while.  Automotive trim tape might work, it's far more durable, but it's also thinner; you'd probably need to use multiple layers.
Rubberstamp Blanks


There is another method of assembling a stamp that involves two pieces of wood.  Basically, you make the stamp as described above with a 1/4" thick wood backing.  Then you glue another, smaller piece of wood on top of that as a knob.  It works really well, providing a very comfortable grip and keeping fingers out of the ink.  In cases where the stamp image requires more pressure on one side than the other, you can glue the handle shifted over toward that side to encourage successful stamping.
Stamp with off-center handle

When assembling a stamp of this type, I usually bond the foam and rubber to the thin layer of wood, then do the carving.  After carving I glue on the second piece of wood for the handle.  For bonding wood to wood, dampen the small piece of wood and use Gorilla Glue or the Elmer's equivalent; it takes four hours to dry, but it holds wood to wood very reliably.  Note that you will need to "clamp" it while drying, which I usually do by setting the stamp face down and putting a weight on top of the handle.

After assembling (or buying) your 3-layer blank, if you have any concerns whatsoever about the suitability of the rubber surface for carving a stamp, now is the time to address it.  Take a piece of cotton cloth (a piece torn from an old T-shirt works nicely), soak a small area with acetone, and stretch it over a flat surface.  Quickly, before the acetone evaporates, set your bonded blank rubber stamp assembly face down onto the wet cloth and slide it back and forth.  The acetone will dissolve the surface of the rubber and the cloth will wipe some of it away.  This will clean and prepare the surface, and it will ensure that the surface is truly flat prior to carving.  This step is especially recommended if you're using an eraser.

If you're working with unmounted rubber, just flip this procedure upside-down.  Lay the rubber on a flat surface.  Wrap the cloth around a wooden block so it's stretched flat across the surface, soak it with some acetone, and apply it to the rubber and rub it back and forth.

This procedure has come to be called "the acetone scrub".  It's not a bad idea to use it on every stamp; it will always result in an excellent surface for carving, even clearing up problems with the rubber that you didn't even notice.

If your Speedy-Stamp has any pimples or other defects, you'll want to use this treatment to get rid of them.  Fortunately, most of the surface of a block of Speedy-Stamp is perfect as is, no real need to clean up the surface in this manner.

This step is often a good idea with Stampeaz PZ Kut.  This is because the Stampeaz PZ Kut has variations in surface texture from perfectly smooth to somewhat coarse -- often on the same piece -- and these may result in differences in how it holds ink.  You can see the surface texture by holding the rubber up to the light and looking at the reflection off of it.

The acetone scrub also enables you to save a little money by buying "B" grade PZ Kut.  The grade of the PZ Kut makes no difference after an acetone scrub, it's all perfect.  It doesn't matter which side of the PZ Kut you use, either.




Navigate to: