Many of the processes and tools involved in weaving are quite specific in their advantages - and disadvantages. One of these processes is that of beaming sectionally.
This is what a sectional beam looks like. In this case the sections are one inch (nominal) in width. Of course the metal staple that divides the sections one from the next takes up some room so the actual width between staples is somewhat less than one inch. About 5/8" if I remember correctly.
Sectional beams commonly come in one or two inch wide sections.
The advantage to sectional beaming is that one can beam a very long, very wide warp without assistance. Sectional beaming is helpful for somewhat fine, somewhat fragile threads. Beaming sectionally is also useful when working with yarns that have twist energy in them. Since the warp is beamed with tension, there is a great deal of control getting the warp onto the beam with minimal tangles.
But there are a number of disadvantages while using sectional beaming, too.
One of the disadvantages is that you need a yarn package for every end in a section. For example, if you have a beam with 2 inch sections and you want to dress the loom with 2/20 mercerized cotton at 36 epi, then you will need 72 yarn packages.
This is a Leclerc spool rack. When I bought it, it would hold 50 yarn packages. Doug added an additional rail which allows me to beam up to 60 ends at a time. Generally this is more than enough for my one inch sectional beam.
The yarns are run through a tension box. This is an AVL tension box which has the great advantage of a swiveling reed at the front which allows me to 'size' the width of the ribbon of yarns going into the section.
Doug modified the box by cutting off the top of the gathering reed and installing a 'gate' that prevents the threads from popping out. Having no top on the gathering reed means that I can very quickly load it.
He also made extra tensioning dowels so that if I am beaming off the top of the yarn package I can apply addtional tension to the threads so that they go onto the beam very tightly. When pulling from the side of a tube or spool, generally the weight of the yarn package is a factor and only two dowels are needed to apply appropriate tension.
Another disadvantage is that if you want a striped warp, it is more efficient to design a stripe that fits into the size of your section. In other words, if your stripe doesn't fit your section, you'll need to remove the yarns and change them in order to get the colours where you want them.
If I want a stripe larger than an inch, I try to make the overall stripe repeat some multiple of 1 inch. Then I fill all of the sections with the first colour combination, remove the yarn from the tension box and spool rack, then load the next combination and fill that colour and so on until all sections are filled.
This can be quite a challenge as for example when I wove a tartan that did not fit within a one inch repeat. Of course each different combination also needs as many yarn packages as required for the size of section that your beam may have.
Fortunately it is possible to beam an ordinary warp onto a sectional beam so there are times when I will do that. I've got a 'slide' show on my website
showing how I do this. Click on Education then on Warping Valet. By using the warping valet it's very easy - but you can run the warp over the top beam of the loom, too. It's a little awkward but can be done.
Ultimately the success of beaming sectionaly is to beam the warp under firm tension. No warp packing is required - no sticks, no paper. When the warp is beamed tightly enough the threads cannot cut down into the lower layers.
One hint - if you do not have a tension box with the front swivel you can use Leclerc 'fingers' to guide the threads into the proper section if you have a Leclerc sectional. If you have a loom other than a Leclerc, it is also possible to use tubing to do this job. Depending on what sort of dividers you have on your loom you can use a size of tube that fits your dividers. Apply the tube to one side of the section you want to fill, then bend the tube over to the divider beside it. Then do the same to the other side of the section. Unfortunately I don't have photos of this because I don't need to do it.
Some bad ASCII art:
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where the ^ represents the tubing going from one divider to the next one beside it and the section to be filled is in the centre.
Currently reading The Sharing Knife (part I) by Lois McMaster Bujold (thanks for the recommendation, Syne!)