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Working with paper
Machine-made paper has a grain to it like fabric does. As discussed in All About Paper, paper starts out as a jumbled mass of wet fibers that dry as they're pulled through the paper making machine. This constrains the fibers along the length of the paper (the direction the machine is pulling them in). Imagine a bunch of little springs that have been stretched out to varying degrees and frozen that way. Because there's no pull on the fibers across the width of the paper, no grain forms, and a lot of shrinkage takes place as the paper dries.
This shrinkage results in (usually) microscopic puckers that run along the grain and act something like accordion bellows, that expand and contract with exposure to heat and humidity. As a matter of fact, paper expands 10 times or more across the grain, than along it. This causes paper to be less stiff in the direction of the grain. Try rolling a piece of paper in both directions, and you'll see that it's less resistant along the grain, and the roll collapses more easily. This resistance is more pronounced when rolling heavier-weight papers.
If the paper comes by the yard, or on a roll, determining the grain is easy; it runs the length of the paper (the curl of the paper runs across the grain). This is usually also the case on sheet paper—the grain runs in the longest direction. If the paper is light enough to tear, it will tear straight in the direction the grain runs, and ragged across the grain (and with heavier papers that tear ragged in both directions, the less ragged edge will be the grain). Another way to determine grain is to wet a small square of paper. Because paper expands more across the grain, the paper will immediately begin to curl up, and the valley of the curl will be the direction of the grain.
To see why knowing the direction of the grain is important, try this experiment. Spread some white glue along one long and one short edge of a piece of printer paper. The short side (across the grain) will immediately start to ripple (called cockling), while the long side (along the grain) will curl up slightly at the edge. The water in the white glue causes the paper to expand much more across the grain, resulting in the rippled effect along the short edge of the paper. The paper only expands a little along the grain, causing the paper to only slightly curl on the long side. While some cockling occurs when you cut the paper at an angle (along the bias, or corner to corner), it's (usually) much less pronounced. The heavier the paper, the less this occurs, but it will still occur. Try this with some arc-weight paper to see for yourself.
Obviously, you want to avoid ever aligning the ends of your arc pattern across the grain. A cockled, rippling overlap is both unsightly and weak. The slight outward curl caused by aligning the end of the arc pattern along the grain should lie flat when glued down, but I've seen some old shades with overlaps that curled out this way (probably the result of over exposure to humidity), and is likely the reason behind many a popped-open seam.
It seems, then, that the best choice is also the most practical, align your pattern anyway it fits, making sure the ends are never directly along the grain, and especially not across the grain. The cockling that occurs with the ends cut on the bias is much less pronounced (if at all), flattens out when glued down, and is least likely to compromise the seam. When making drum shades, you may well have no choice but to cut the ends along one grain direction or the other. Handmade paper has little to no grain, but you may want to try the above glue experiment just to make sure it's not an issue.
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Getting the curl out
One of the most frustrating aspects of working with Dulcote is that it comes rolled up and is really resistant to flattening. And the same can be true with other rolled papers. I was tickled pink to discover that there's an easy way to get paper to relax and uncurl, if not perfectly flat, flat enough to work with. Always flatten paper before cutting out the arc, as some shrinkage may occur.
Use a damp sponge to slightly dampen the paper on the back of the curl (here C ). While a spray bottle might work, unless it's a really fine mist, it will probably get the paper too wet, which can cause changes to the surface texture (experiment to see if this happens). By the way, this only works if the side of the paper your dampening has no coating on it; if the water beads up on the surface, this won't work. Fortunately, the coated side of Dulcote is on the inside of the curl.
Expose the dampened side of the paper to a heat source. I've tried this with lightbulbs, with the paper proped up vertically on my open oven door, and with a hairdryer. (For some reason) I haven't tried using the sun, but I bet that works, too. The hairdryer is definitely the fastest, but takes constant attention. If you have the time, and especially if you've got lots of paper to flatten, try setting up some clip lights so they're positioned fairly close over the surface of your paper.
The first time you see this, I know you're gonna think it's as cool as I did. Initially, the paper will curl up even more, but as the dampened side dries, the paper magically begins to flatten out. The only tricky part is that the second it gets perfectly flat it begins to curl in the other direction (for example: if it curled horizontally toward you, it will begin to curl vertically away from you). This happens in an instant, and you need to be prepared to remove the paper from the heat source just before this moment. This is particularly important with Dulcote, because the coating on the other side won't allow you to flatten out the newly formed curl.
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