Choosing Batting for Lap-Sized Work
Okay. Your top is joined, your rows are done, and now we build the sandwich. First decision: batting.
There are a lot of options at the store and most of the packaging is trying to sell you on things you don't need yet. So let's keep this simple.
What you're actually choosing between
For lap-sized quilts, I want you looking at three things: fiber, loft, and how it's packaged.
Fiber. Cotton, cotton-poly blend, or poly. Honestly, for a beginner's lap quilt, I'd go cotton or a cotton-poly blend. Cotton batting quilts flatter, feels more like a quilt you grew up with, and it breathes better once it's on somebody's lap or draped over a couch. Poly batting is warmer and puffier and it's fine, but it can make your free-motion designs look a little inflated, like the quilting is fighting the loft instead of sitting in it. That's just my preference. Plenty of people love poly and I'm not going to tell them they're wrong.
Loft. Loft is how thick the batting is. Low loft is thin and flat. High loft is puffy, the kind you see on tied comforters. For lap quilts that you're going to machine quilt yourself, low to mid loft is what you want. High loft batting under a home machine is a wrestling match. It doesn't feed evenly, it bunches at the harp space, and it makes your stitches look sloppier than they are because the fabric's fighting you the whole time.
Packaging. You'll see batting folded in a bag or rolled on a bolt. Folded batting has crease lines from sitting packaged for months, and those lines do not want to relax overnight, no matter what the label promises. If you're buying folded, get it out of the bag and let it breathe for a day or two before you baste, more if the creases are stubborn. Rolled batting from a bolt doesn't have this problem, which is one reason I'll pay a little more for it when I can.
What I actually use
For a lap quilt, my go-to is a cotton-poly blend, low loft, off a bolt if the store has it cut to size. It's forgiving, it doesn't shift much once it's pinned, and it gives me a little bit of loft so the quilting shows without turning the whole thing into a marshmallow.
If you're using something from your stash that's been in a bag in the closet for two years, that's fine. Just plan for the wrinkle-relaxing step. Don't skip it and then get frustrated when your basting looks lumpy. The batting's not being difficult on purpose, it just needs time to remember what flat feels like.
Cutting it to size
Lay your backing down first, then your batting on top, and cut the batting a couple inches bigger than your quilt top on all sides. Same rule as backing fabric. You want extra to work with, because things shift a little as you pin, and you do not want to run short an inch from the edge and realize it.
The check I do every single time now
Before I baste anything, I run a hand flat across the whole batting piece, corner to corner, feeling for lumps, thin spots, or a seam if it's a pieced batt. This habit exists because of a mistake, not because I'm naturally careful.
Years ago I quilted almost two feet across a project without noticing my bobbin had run out. No thread underneath, just needle holes punched clean through, top thread with nothing to catch. I didn't catch it until I flipped the piece to check my tension and saw a strip of nothing staring back at me. Now I check things before they become two feet of a problem. Bobbin before I start a section. Batting before I baste. It's not paranoia, it's just cheaper than redoing work.
A real caution
If you're using spray baste anywhere near your batting, do it outside or in a very well-ventilated space, away from anything you're eating off of, and keep it off your skin. I don't reach for it much for lap-sized work, I'd rather pin baste and skip the fumes and the sticky floor, but if you do use it, read the can and give it room to breathe before you're breathing near it.
Before next time
Pick up your batting for your practice piece and get it out of any packaging tonight so it has a few days to flatten out. We're pin basting next lesson, and flat batting makes that whole process about ten times less annoying.