Acrylic vs Wool Yarn

The craft is unusually snobbish about this, and the snobbery costs beginners money. Wool is the better fiber at a long list of things, and none of them matter for a machine-washed throw. What follows is the comparison on the six axes that actually decide a project, with the trade-off stated in both directions.

The short version

Memory is the real difference

If you take one thing from this page: wool springs back and acrylic does not. Wool fiber is a natural coil with scales along its length; stretch it and it wants to return. Acrylic is an extruded synthetic filament with no such structure - stretch it repeatedly and it stays stretched.

That single property explains almost every complaint about acrylic garments. The cuffs on an acrylic sweater go loose and stay loose. An acrylic hat brim widens over a winter. Acrylic cables flatten out and lose the raised, sculptural quality that made you knit cables in the first place. None of this is a manufacturing defect; it is what the fiber is.

It also explains why acrylic is genuinely fine for a blanket. A blanket has no ribbing to relax, no cuff to widen, and no shaping to lose. There is nothing for the missing memory to ruin.

Blocking: wool changes, acrylic does not

Blocking is wetting or steaming a finished piece and pinning it to shape while it dries. On wool it is transformative - stitches even out, lace opens up, a lumpy swatch becomes fabric. The wool takes the new shape and holds it.

Acrylic does not wet block. It can be steam blocked, which crafters call killing the acrylic: applied heat permanently relaxes the fiber, producing a softer, drapier fabric that will never spring back again. It is a one-way operation and worth knowing about, but it is not the same tool. If a pattern's shape depends on blocking, it depends on wool.

There is a complication on the wool side too, which is that superwash-treated wool blocks differently from untreated wool - it grows more and recovers less. That is covered in does superwash wool block.

Warmth, and the wet-weather case

Both fibers insulate by trapping air, and a thick acrylic fabric is warm. The difference shows up when the fabric gets wet. Wool absorbs a large share of its own weight in moisture before it feels wet, and it insulates while damp. Acrylic does not absorb; water sits in the fabric and against your skin, and the garment goes cold.

For an indoor blanket this is irrelevant. For a hat you will wear in rain or snow, it is the whole argument.

Washing: the axis where acrylic simply wins

Untreated wool felts in a washing machine - agitation plus heat locks the scales together and the fabric shrinks irreversibly and dramatically. Patons Classic Wool is hand wash and dry flat, and that is typical of untreated wool.

Acrylic goes in the machine and the dryer. Red Heart Super Saver is machine wash warm and tumble dry low; Lion Brand Heartland is machine wash gentle, tumble dry low.

Superwash wool closes most of this gap - it is wool treated to be machine washable - at the cost of some springback and a chemically intensive process. Superwash versus non-superwash works through the trade.

Softness, itch, and what is actually happening

Wool itch is a mechanical effect, not an allergic one. Textile research puts the prickle threshold at roughly 30 micrometers of fiber diameter: fibers coarser than that are stiff enough that their ends do not bend when pressed against skin, so they push into it and trigger the nerve endings that register as itch. What matters is not the average fineness but the proportion of fibers above that threshold.

That is why merino - typically in the 11.5 to 22 micron range - does not itch while a coarse tweed does, and why 'I am allergic to wool' is almost always 'this wool is coarse'. Someone who reacts to a scratchy jumper will usually be fine in merino. The full argument is in best non-itchy yarn for sweaters.

Acrylic can be very soft - Caron Simply Soft is named for it - and softness is the axis on which acrylic competes most credibly. It just achieves the softness with drape rather than loft, which is why soft acrylics hang rather than stand.

Pilling, which is a construction question more than a fiber question

Both fibers pill. What decides it is yarn construction - how tightly the fiber is spun and how long the individual fibers are - not whether the label says wool or acrylic. Acrylic pills are more visible and harder to remove because the fiber is strong: the pill stays attached where a wool pill breaks off.

Some acrylics are engineered against it. Lion Brand Basic Stitch Anti-Pilling is sold specifically on that property. The mechanism, and what actually helps, is in why yarn pills.

Cost, honestly

Acrylic is the cheapest yarn on the shelf per yard, by a wide margin. A 7oz skein of Red Heart Super Saver carries 364 yards; a 100g ball of Patons Classic Wool carries 194. For a large blanket, that gap is the difference between a project you start and one you do not.

The middle ground is a blend. Lion Brand Wool-Ease is 80 percent acrylic and 20 percent wool, machine washable, and gets you some springback for close to acrylic money. Whether blends are a genuine best-of-both or a compromise is worked through in are wool acrylic blends any good.

How to choose, in one paragraph

Choose wool for a fitted garment, anything with ribbing or cables, anything you want to block, hats and mittens for real weather, and socks. Choose acrylic for blankets, anything for a small child, charity knitting, anything the recipient will machine wash, and any project where the yardage cost decides whether it happens. Choose a blend when you want machine washability with some structure, or when you are stepping up from all-acrylic and are not ready for hand washing.

If this is your first move away from acrylic, the sequence that works - and the one that does not - is set out in upgrading from acrylic.