I just knit up a vest back, that I made a pattern in a knit/purl kinda fashion. It is a square maybe 5 x 5 ins.

It kinda puckers in the back, and is dipped in in some places and sticks out in others…

This is an acrylic yarn, so I am not sure that I can block it flat.

I was thinking, do you think a square of fusable interfacing ironed on to the back of that pattern might hold it flat(er)?

Don’t think so. It’ll show up every bubble and wrinkle and irregularity. And it will change the drape of the piece so that it doesn’t look knitted anymore.

Try washing the piece, patting it down flat and letting it dry. Acrylic isn’t supposed to block, but a good washing can improve it.

If that doesn’t work, you can try a process called “killing” the acrylic. This involves steaming it, but not getting it hot enough to melt the fibers. You can use a steam iron or one of those vertical steamers. Don’t let the hot iron touch the fabric – just send puffs of steam through it. Again, pat it flat and let it dry. This treatment may change the texture of the fabric and make it drapier, but shouldn’t ruin it. But do try it on a swatch first.

Actually, if it ends up drapier, I wouldn’t mind that. The piece seems a bit stiff as it stands, and a little bit of give would be nice smiles

Interfacing won’t make it drapier, more like stiffer, but you can get a light weight interfacing that wouldn’t make it too stiff.

p.s. You can always test a swatch to see how it will drape.