FACT: Carvers are very loyal and passionate about their carving tool of choice.
I, for instance, am a devout gouge carver. And not just any gouge, but the Staedtler is my choice. I have tried just about every other carving option, and I have found it to work best for my style of carving.
There are several options, though, and I'll attempt to list them here, just for the record.
The X-Acto Knife
an angled x-acto knife with safety cover
Just your basic x-acto knife, except the one with the sharp point is the one easiest to use for carving rubber. Nitrocat created an excellent tutorial on knife carving HERE.
The Wire KnifeSimilar to the x-acto knife in theory and execution, it is much smaller. Created by Kirbert, these are only available from him (see photo below). I have given this tool a try, HERE is my review.
needles of different gages, one inserted into a pin vice
There is always much talk and mystery surrounding using needles. Simply, they are hypodermic needles used for large livestock (horses, cows, etc.). Definintely a good part of your carving toolbox, I have found, for very small detail and for sharp corners. Here is my REVIEW of needles. They are available at any feed or farm supplies retailer and also online (HERE is one site I found just googling a bit).
If you are going to use needles, you will need to fashion a handle of some sort. The most popular choice is the pin vice (pictured above), but you can also use a drafting lead holder (pictured below).
wire knife inserted into drafting lead holder
the set of three Staedtler gouges
Another carving option is the gouge; a sharpened v-shaped metal tip attached to a handle that you push through the carving material. Cutting both angles of the material in one pass, the gouge differs from the carving technique of knife carving that only cuts one angle at a pass.
a Speedball gouge with a variety of removable nibs
There are two choices for gouges, Speedball and Staedtler. As I have stated before, I prefer the Staedtler; the metal seems so much more smooth and the design seems far more 'engineered' than the rather rough Speedball gouge. The bottom of the cutting 'v' is sharper and thinner on the Staedtler than on the Speedball, as well. The advantage to the Speedball is that the nibs or carving tips are removable, so they are easily replaced. Not so with the Staedtler, when the blade gets dull either you sharpen it or buy a new one.
I found this opinion interesting, again from our friend Kirbert, on comparing the Staedtler and the Speedball:
"...Then I tried a Speedball #1. After working on the precision instrument that is the Staedtler 1v, just looking at the Speedball with the magnifying lens makes you think "What a piece of junk!" Cutting a sample groove, I am astounded that -- having just made a hair-width groove with the Staedtler -- I am completely unable to cut a groove anywhere near that fine. It's gotta be three or four times as wide at least, and I was trying hard. It's just not happening..."Noteworthy Alterations & Tricks
The first and most discussed tool alteration is the 'pinching' of the #1 Speedball nib, thus making it smaller or thinner. This is achieved by heating up the nib and giving it a squeeze with some sort of tool, such as needle-nose plyers. This is tricky business, however; I've heard of folks going through several nibs trying to get the heating just right so the nib doesn't crack.
I have tried this tool, and since it's made with a Speedball nib, I didn't like it any better than the regular #1 Speedball nib - but I know that some do, so it may be worth a try.
the pinched Speedball nib
Another alteration is the reverse Speedball nib; instead of the 'v' shape that is typical, the reverse nib leads with the sharp bottom of the v, with the sides angling back toward the carver. (I actually had one of these and gave it a try, but quickly determined it was not for me. Unfortunately, I cannot find it to get a better photo.)
a "reverse" nib, filed back the other way
Something else to add to your knowledge is different ways to create circles or texture in the rubber with various household items. The tip of a mechanical pencil is an excellent choice (push back the lead all the way, then insert the tip and push down into the rubber, thus creating a perfect tiny circle). Paper clips have also been used with success and come in various sizes. Rough sandpaper has been used, as well, for roughing up the rubber for added texture. With a little imagination, you can come up with more ideas on how to create unique looks on your stamps with things right around your house.
Sharpening Your Tools
In my personal experience, I have not had any luck sharpening my carving tools. I have tried it myself and also had a friend give it a try, to no avail. Since you can now purchase Staedtler 1v gouges from WEBFOOT for minimal cost, I just buy a new one when I feel that the tool is getting too dull (which isn't frequent, that's for sure - the Staedtler holds an edge for hundreds of stamps). As far as knife carving tools and needles, they are also so inexpensive that sharpening is just not necessary.
[UPDATE: our friend Kirbert will sharpen gouges for you for minimal cost/postage. Contact him HERE]
Making the Choice
I highly recommend trying all the types of carving tools I have highlighted above. Newer carvers need to find what works best for them and the more experienced would do well to expand their horizons by trying a different tool or technique. Your personal carving style, material of choice and carving environment all play a role in your choice of carving tool. Many veteran carvers, such as myself, have a whole arsenal of tools at their disposal to make just the right cut.