Several sources recommended interfacing as used in sewing rather than paper. I found it in a fabric store for about $2 a yard in bolts that were 20 inches wide, sufficient for a tombstone. I estimated about a yard per tombstone which proved reasonably accurate. I asked for a non-fusable medium weight interfacing. Fusable interfacing has a heat-activated adhesive on the back. It was also recommended that one try to get one that doesn't pill, forming little tufts of loose fabric. The advantage of interfacing over paper is that it is more durable, less likely to tear and will pack easily if traveling, an important consideration for me.
It is recommended that one bring a soft brush and water to clean a tombstone first and ones which are fragile or covered in lichen are to be avoided out of concern for damaging the tombstone. I may find that the tombstones I wish to do rubbings of don't lend themselves to the procedure for these reasons.
For my practice run I went to a nearby cemetery where I had done some research for a client whose great-grandparents came to Minneapolis/St. Paul in the 1880s. I had taken photos of these tombstones for her and thought she might be interested in the rubbings as well. The tombstones had Hebrew writing on them so were similar to what I expected to find in Belarus.
My basic tool kit was a roll of interfacing, scissors, artist tape (masking tape would work as well) and an inexpensive set of oil pastels (crayons would work also). I called ahead to the cemetery to ask if it was all right to do rubbings. Some cemeteries don't allow it for fear of damaging tombstones. This particular cemetery said it was OK.
After finding the tombstones for which I wished to do rubbings, I cut a piece of interfacing to fit. My estimate of a yard was almost exactly right for the tallest one. I then taped it to the tombstone on all sides. The sides of the tombstone were left rough so it was hard to get a good seal. As the day was windy, getting the fabric taped on was the biggest challenge. A second set of hands would have been helpful to hold it taut while I did the rubbing.
I then used the side of the oil pastel, moving it in one direction to go over the letters. The image of the tombstone began to magically appear. I experimented with some different colors to see the effect. While I attempted to go over the image several times the looseness of the fabric against the tombstone made it difficult to do so without obliterating part of the image. When I returned home, I ironed the fabric face up with an old towel on top. I pressed down, rather than moving back and forth, to set the wax into the fabric.
So what did I learn?
1) Keeping the fabric taut is critical to getting a good image. Bring another person with you to help hold the fabric taut. I didn't go over some of my images as the fabric wasn't taut and it began to obliterate part of the image.
2) It is rather messy. My hands were covered with oil pastels so I added two things to my travel kit- a pair of plastic gloves and a plastic garbage bag to put the finished rubbings into.
3) One tombstone can use up most of one oil pastel so I need to bring enough of the colors I want to work with.
4) I also found that the interfacing that I got did pill and that can affect the clarity of the image.
5) I will be flying and just bringing carry-on luggage so can't bring a pair of scissors. Perhaps they'll let me keep a small pair of nail scissors. Otherwise I will need to purchase a pair of scissors there or ask my guide to bring some.
I've included an image of my trial result. You can see the result of fabric that isn't taut against the stone in the word "father".