You can use any type of bead, or size of bead, on the loom. I prefer Miyuki Delicas size 11/0, mainly for the color palette they offer. Over 1,003 colors, of beads and finishes. Tohos offer about 260, at this time. Therefore, when wanting to paint a picture in beads, it may be best to consider the best palette options. Miyuki Delicas, a tubular shaped bead, in size 11/0 is my favorite, mostly for the palette available. The Tohos are the same shape, but have a larger hold, in the center. Again, not as may colors, 260 or so. The other bead option, in this same shape, is Toho Aikos. Also a tubular shaped bead, appx 970 colors, in their palette and are found in size 11/0 too. All three of these beads are tubular and perfect for weaving on a loom.
In the order of which are sized more even....meaning, “not much need for culling”.. [or picking similar sizes from the bead cup], Aikos are the best sized and more even. They are the most expensive 11/0 tubular seed bead. Some grams of Aikos can run about $17.00 per gram. Tohos and Delicas are similar in their culling traits. The matt beads require more culling. Opaque or metallic beads offer the need for less culling. Together, the matt, opaque, or metallic beads are different in sizes themselves. There is no problem weaving any of these different beads on the loom, even together.
There are approximately 175-200 Delica beads per gram. The variance between the 175-200 is that the matt beads are lighter in weight than the opaque or metallic. But, if you count, considering 200 beads per gram, then you should always purchase enough to complete your piece.
You can buy Delica beads by the gram, at some sites, on the web, or in 4, 7 or 10 grams weight quantities. Divide the number of grams into the total cost and get the ‘price per gram’. This will help you decide the best price, for that color/finish bead, when you are purchasing them. Some bead suppliers offer better prices on certain bead color/finishes, than others, so I do the math, for each bead color/finish, in my order and shop that way. I will also factor in the shipping costs, because shopping multiple sites, for one bead project, needs to be planned out accordingly.
As for the measurement of your finished looming and considering the final size, I have created this photo to demonstrate the count, 1 inch by 1 inch:
You can count the beads yourself to determine the width of beads and the length of beads. These are Delicas woven on a loom. You may want to weave your own personal patch and measure yourself, incase your tension is different than mine.
Of course, you can also use round seed beads, in size 11/0. Their color pallets still do not come near the number Miyuki Delica offers. You should consider the Japanese made round seed beads, as opposed the Chinese or Czech. The Japanese made 11/0 seed beads are more evenly sized and not so much culling needed. Sometimes, even purchasing Czech or Chinese 11/0 seed beads on a string opposed to loose in a bag, make a difference in how much you will need to cull out perfect shapes and sizes.
Mixing the two different types of 11/0 beads together, in one weaving, makes for an interesting look. Be aware that you may either bulk out the larger beads, which create a nice texture to your bead work, or your edges may become wavy. Again, a nice look if carried out through the entire piece. Recently, I worked with using 11/0 Japanese Seed Beads and 11/0 Miyuki Delicas, in one design. I had to make some technical changes with my warps/wefts, to create the 'flat, even, 3D texture I wanted to acquire'.
If you are interested in creating some more advanced patterns for the loom, look into BeadTool on the web. They offer a free trial, where you can play around but not able to print, until you purchase the program. The only other bead pattern program on the market, which will give you a graph of beads relating to your color chart, is Bead Creator Pro. Much higher priced, and offers a bit more control over a pattern.
I also suggest experimenting, with different beads, different threads (warp or weft), and attempt adding 3D interest to your bead weaving.