Originally Posted by amma
After you wash the quilt and it is still damp, you lay down a sheet on your carpet and put the damp quilt on top of it. Then you can block it (which means you are going to straighten and square it up) by pinning it to your carpet. I put the pins in at a angle. Then I put a fan blowing on it to dry.
I usually have to use a fan as well. Just be sure to measure it through the middle, both vertical and horizontal. You will know it is square when you can measure on the diagnal, from one corner to the other (like a big X on the quilt) and both measurements come out the same.
I found this explanation from Google -
http://www.quiltuniversity.com/squaring_up.htm