Reed Substitution Chart
When you don’t have the ideal reed for the sett (ends per inch), you must substitute one that you do have. Reeds go by dents per inch—meaning the number of spaces in the reed in one inch. The ideal reed accommodates two warp ends per dent, so that knots can pass through, and to avoid reed marks. The main thing you want to do is retain the epi (ends per inch) required.
Say you want to have 10 threads in one inch, and you have a reed that will give you 8 threads in an inch, you need to change from the ideal of 2 threads per dent to something else.
So, look for the sett (epi) you require (here, 10) in the column headed by the reed that you want to use (here, 8).
Look over to the left column (next to 10) to see the sequence that you will need to sley the reed to attain the sett you need. I see that what is given for an 8-dent reed for 10 epi, is sequence: 1-1-1-2—that is, one thread in a dent, another single thread, and yet another, then, 2 threads in the next dent. Or, 3 single threads per dent, then, a double. Repeat these 4 dents for all the warp threads.
Another example, which isn’t so pretty, is one where it doesn’t quite work out for the exact sett you want, and you have to compromise. You have to pick the one that’s close enough.
If your sett is 12 epi, and you only have a 10-dent reed, you would look in the column for 10 dent reeds and note that 12 ½ is close enough.
Then look over to the left column to see the sequence (order) that the threads should be placed (sleyed) into the dents: one, one, one, two.
These are useful to have on hand. However, when I want to know something like this quickly, I often ask Google, etc.
These formulae can be useful to have on hand. However, I bet they are also on the internet!