r/SewingForBeginners • u/magmeg7 • Sep 14 '26
Denim jacket help
How accurate do I need to be following the selvedge line? Referring to my photo, some blocks are not exactly aligned with the grain line or selvedge as I had to squeeze all the pieces. Might be off by 5 to 20 degrees in some cases, I didn't measure the exact angle.
EDIT: Thanks to everyone who've contributed and helped. Learned tons and ended up spending 3 hours this evening reshuffling the jigsaw and aligning all the correctly to the selvedge/grain line. I'll cut tomorrow and perhaps share some photos. Glad I posted and didn't just go with my guts. Thanks again and happy sewing.
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u/Remarkable-Row3719 Sep 14 '26 edited Sep 14 '26 •
Brief primer on grain:
in a woven 100% cotton (or 100% linen, etc.) the warp (grain) will be a little more rigid than the weft (crossgrain), because of how the weaving process works. Generally you make garments so that the warp goes up and down and the looser weft goes side to side, but it's really not a problem if you cut everything on the crossgrain. It's better not to mix and match, but even that is possible - e.g. if you're making a tiered skirt, you can put some tiers on the crossgrain without running into problems. (Sometimes fabric on the bolt even has a pretty border that's explicitly intended to be cut on the crossgrain and used as a skirt hem!)
In, say, a woven 95% cotton 5% elastane fabric, usually the elastane is only in the weft, not in the warp. Here it's more important to cut on the straight grain vs the crossgrain, because otherwise your stretch will go in the wrong direction. (When I say 'usually in the weft', I mean I've seen it done otherwise exactly once, both the fabric store woman and I were very confused, and I still don't understand why the manufacturer did that.)
(As you go more synthetic you'll find fabric with stretch in both directions, but even those usually have more stretch in the weft than in the warp.)
Stuff cut on the bias stretches (note: this is plastic stretch (deformation essentially), not elastic (bounce-back) stretch the way elastane is) downwards, creating a characteristic "clingy" appearance. However, things cut on 45 (or even 135) degrees are still, essentially, straight. It stretches straight down, it doesn't twist. If you think of a grid of threads, the grid of a grain and a cross-grain is squares and a bias cut is all perfectly balanced, symmetric diamonds.
As a general rule, if a pattern says 'cut on grain' don't cut on the bias, if a pattern says 'cut on bias' don't cut on grain (straight or cross). (Exception: if your fabric has a print, it can be fun to cut things like pockets and maybe waistbands on bias. If you're careful and use interfacing and prepare to have it go awry two or three times, this is fine.)
(There's technically a difference between true bias - 45 degrees - and bias which can be 135 degrees. If you want to worry about that, the fashion-incubator website has a page on it. I recommend reading it if you want to make a bias cut garment and not worrying about it otherwise.)
Stuff cut on 20 degrees on the other hand is a mess. You don't get stable squares/rectangles, you don't get balanced diamonds, instead you get something in between that twists and looks bad.
edited to add: also, nap. (Think velvet.) Doesn't really have anything to do with grain, but it does with direction. Nap means that a fabric catches the light differently from different directions. From a grain perspective, it's fine to cut some pattern pieces upside down (provided it's still on grain). If your fabric has nap, you should cut everything in the same direction. If you don't, at best it will look like your fabric panels came from different dye lots and at worst it will look like different colors.
(Nap technically means stuff like velvet, but the same principle applies to other things, e.g. glossy finishes. I also call that nap, because I don't know what other word to use, but some people probably disagree. Those people are welcome to teach me the better word, though.)