I usually make baby blankets with a fleece backing but for my extra-precious preemie niece I have ordered some Minky fabric as I hope it is even softer.
What kind of stitch size / tension works best? I have stupidly ordered a piece only about 1.5cm bigger than the blanket so not much scrappage to experiment on! I will be quilting it with cotton and a very thin fleece quilting interlayer.
I wouldn't like to be quilting (as in proper quilting ie shapes and swirls on the top of the quilt to hold the "sandwich" together) with Minky, would be worried about all the lovely squishy fibres being flattened down with your stitching.
If however, by quilting it you mean that you are just going to join with minky to a layer of cotton with wadding in the middle and no "quilting", you may have trouble with the wadding slipping around, especially if the blanket is going to be washed
Perhaps you need to just use the minky as the backing, your cotton as the top and sew, right sides together, no quilting to make a lovely blanket. As for sewing it, I would just sew with a small/medium stitch and usual tension <lazy seamstress>
I'd be worried about only having 1.5cm to play with though, especially if you are going to "quilt" as the wadding/backing always need a good bit bigger than the top as they seem to shrink a little under the heavy stitching.
Does that make sense? Sorry if I've not explained that terribly clear, just typing fast before I go and collect DD.
Minky is a swine to sew with. You'll need about a billion pins - seriously, pin every inch or so, the whole way round. It stretches and slips. It also sheds like a swine when you cut it - be careful as it's for a prem baby, the shedding might be a problem. It is gorgeous stuff though, much softer than fleece, more like velvet only more so.
When I did my jelly roll quilt (backed with minky) I quilted in the ditch but only the wadding and quilt top, then added the back seperately, using it to bind as well. I quilted the seam between the quilt top and binding through all layers (iyswim) so that the quilt stayed square when in use.