We get questions from people who have purchased rug patterns (from other folks) and wonder why they can't get them to work. So here is a primer on how crocheted rag rug patterns developed and how they work.
Back-and-Forth Crocheted Rug Patterns
There are basically two sorts of patterns for making crocheted rugs. The first type is a back-and-forth construction. (Begin with a base chain the desired length, chain 1, insert the hook in the 2nd chain from the hook and make a single crochet. *Single crochet across the row, turn work, chain 1, and repeat from*.) These patterns may use half double crochet, double crochet, or specialty stitches. With this type of pattern, the fabric strips should be cut straight on the grain of the fabric, usually ¾ inches wide, and not more than an inch wide unless you are using very lightweight fabric. If all of the rows are the same length, these patterns will create a rectangle. If the rows are of varying length, unique shapes can be created. Some people are making crocheted rugs in the shape of the various states (in fact all 50 states are now available) using this type of pattern.
In back-and-forth crochet patterns, the only trick is to size the hook to the weight of the strip, and not work really tight stitches. Heavy fabrics and wide cotton strips don't work well for these types of rugs, since a prominent ribbed effect is created.
Radial Crocheted Rug Patterns
The second type of crocheted rag rug pattern is the "radial" construction which is the standard crocheted rug. These begin from a round center or a base chain and are worked around and around the center, always stitching in the same direction. In the 1800's to the early 1900's, patterns for these types of rugs most often were quite general, using such phrases as "increase as necessary to make the rug lie flat". The strips for these rugs were cut straight on the grain of the fabric, and the rug makers of the day made the rugs by "feel". With practice they knew about when to add stitches to keep the rugs shape and allow the rug to lay flat.
Some early crochet patterns used the device of working rag strip over clothesline. This was done for two reasons: the stiffness of the clothesline helped to force increases which helped the rug lay flat and/or the fabrics used in the rug were so worn that the clothesline was needed to give the rug body. Unfortunately cotton clothesline used in rugs shortens the life of the rug. It holds water when the rug is washed (leading to damp rot), and the clothesline itself has a harder texture than the fabric, so that the fabric wears through faster.
By the 1920's, several crocheted rag rug patterns appeared where someone with the "feel" of rug making wrote down the stitches they added as they worked. Unfortunately these old patterns most often did not work for someone with a different touch in crocheting. For that reason, patterns in the 1930's and 1940's often called for the fabric strip to be cut on the bias so that it would have enough give to work with the written patterns.
So two schools of thought developed-one which called for bias cut strips of cottons, and the other which used straight cut (or torn) strips. Of course in moving away from the traditional straight strips, the rugs were supposed to be easier to make, but unfortunately the resulting bias rugs continued to stretch, even after they were made, and didn't hold their shape well.
In the 1930's and 1940's crocheted rugs were also made with recycled stockings, instead of rags. The stockings had a built-in stretch and resilience so that they acted like yarn, and the rugs were made from regular yarn rug patterns (which will not work with fabric strip).
Even through the 1970's, when I began researching rug making, such venerable sources as Better Homes and Gardens were still publishing directions for radial crocheted rag rugs saying "increase as necessary" which is not very useful to a beginning rug maker.
Research on Crocheted Rag Rugs
It was not until the early 1980's that I began to conduct experiments with fabric strip for crocheted rugs, to determine why the old radial patterns for rug making simply did not work reliably and did not work with patterns that did work for yarn rugs. The very first fact that I discovered was that fabric strip--even when cut on the bias--does not act the same way as yarn does. Straight-cut fabric strip has no 'give' like yarn does, and bias-cut fabric strip will stretch out, but does not have the resilience to resume its original shape as yarns will.
Working with the traditional straight-cut fabric strip, I experimented extensively to develop an increase pattern which would work for radial crocheted rug patterns. That increase pattern worked so well that it was adaptable to crocheting rag rugs in all sorts of shapes all of which laid flat, every time, no matter who was handling the crochet hook. The pattern was the breakthrough which allowed the full development of fabric tapestry rugs. In 1984, the increase pattern was first published (under formal copyright), and again in 1997 in the book "Crocheted and Fabric Tapestry Rugs". The most recent version is The third of the Rugmakers Handbook Series "Croched & Fabric Tapestry Rugs" published in 2008.
So, while our books all deal with traditional crocheted rugs (e.g. made with straight cut, not bias, strips), the directions are based on the increase pattern which was only recently developed. That is why our rugs are so consistently shaped, and the fabric tapestry patterns are so symmetrical. Because of the copyright protection, we are the only source for books using this increase pattern.
Old Rug Patterns Available on the Internet
There is a lot of information about crocheted rugs on the internet, and even some free patterns, such as the one for a 1930's style bias cut (oval) crocheted rag rug on About.com. The instructions are an interesting piece of rug history so long as you understand the shortcomings of bias-cut rugs, and old patterns. Don't be discouraged if the pattern doesn't work for you, since it is an old-style pattern relying on the 'feel' of the original rug maker.
Finding Crocheted Rug Patterns that Work
If you are looking for rug patterns of any sort, look at the rug pictured. Is it evenly shaped? Is the rug shown laying flat? Be especially careful of directions that show a rug draped over something 'artistically'. This is often a device to hide the fact that the rug doesn't lay flat. Also be careful of directions that show a picture of a rug with something else sitting on it. This trick is often used to hide the fact that the shape is not good (often seen with poorly done heart rugs).
Another recent gimmick is to have the crochet stitch pass only through the back thread, leaving the front part of the top of the stitch exposed. That allows the rug to stretch, covering up a poor pattern. There are also modern directions that call for the use of Huge Hooks, creating a piece that has large visible holes. If you pick up one of those type of "rugs" your fingers will go right through it. Frankly, I regard those as doillies, not rugs, and the only practical use I have seen them put to is as automobile seat covers to protect bare skin from hot seats in the summer. If used on the floor they are a real tripping hazard.
Be cautious of crocheted rug patterns that call for fabric strip to be cut on the bias. These are most often derived from older patterns which require the fabric strip to stretch in order for the rug to lay flat. Similarly, patterns which call for fabric strips to be cut very wide (over 2 inches) create a very lumpy look. These are most often touted as being "quick" to make, but in reality, are mostly a device to sell patterns, not teach people how to make functional and attractive rugs.
Advice to Beginners
With the growth of the internet there are hundreds of craft sites and videos available and it is a common assumption that all crocheted rug patterns are the same. I get letters from frustrated rug makers who followed those online directions only to end up with a rug disaster. All I can say is start with proven directions. I simply will not waste my time trying to undo the damage that poor directions create. While that may sound like a shameless plug for my own books, those directions have a long, proven track record and they are available at reasonable cost on Amazon and other booksellers.