I usually collect hankies until I have enough of the same size and simply put them together in the normal way for a rag quilt but I had so many hankies of various sizes that I was not using because I didn't have enough of a particular size. I wanted to figure out a good way to make the quilt using all the different sizes. I thought I could put a small size next to a big size and it would all work out in the end but the seams didn't match up and I didn't like the look so here is what I did instead.
Step 1: Sort and organize your hankies as to size. I have an 11" pile, a 12 - 12 1/2" pile, a 13 - 13 1/2" pile and a 14" and above pile.
Step 2: Iron each hanky and inspect for yellowing. The ironing will help you get the correct measurement.
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If your vintage handkerchiefs look yellowed you can try a trick I found on Pinterest that really worked. I found it here. I wish I had taken the "before" picture of this hanky I tried it on but here is the "after." It looks amazing!
Step 5: Take a picture of your layout. You don't really have to do this step but I find that my cats love to mess up my layouts. The pictures have saved me many times. Pick up the hankies by row so it will be easy to sew in the right order.
Step 6: Select the largest size hanky and cut your flannel that same size. I am using flannel and fleece for this rag quilt. I like to use fleece with the very delicate hankies to give the quilt a nice weight. I cut my flannel and fleece squares 13 1/4". (The 1/4" was just my insurance.)
Step 7: Layer the hanky and the flannels (and fleece if you are using it). I've made hanky quilts with just a hanky and two slices of flannel and it turns out beautifully. For this one I layered hanky, flannel, fleece and flannel. If the hanky is close to the size of the flannel squares then simply sew your traditional X through all 3 or 4 layers.
If your hanky is smaller than an inch from the edge of the flannel like this:
Like this
Then layer the other fabrics and sew through all the layers with the traditional X like this
Step 8: When all the smaller hankies are sewn onto flannel and layered and all the hankies are sewn with an X, now you can begin to assemble the quilt. Alternate the small hankies with the large hankies as you did in the original array and sew them together in a row. I used a one inch seam on mine for a very fluffy look.
Step 9: Sew all the rows together matching the seams as you go.
Step 10: Sew around the perimeter of the quilt. I do a double perimeter seam for added strength and I think it looks pretty too.
Step 11: (Gently lift cat off quilt) Clip all the seams as you would any rag quilt.
Step 12: Machine wash your quilt. With Hanky quilts I use a delicate setting and dry on low. They wash up beautifully and this last step helps to give a nice full fluffy look to your seams. Admire your results:
Update 2/23/14
I have sometimes cut through the hanky edge as part of the fluffy seams but if you don't want to cut into your precious hankies, make all your flannel squares 1" larger than your largest hanky. Sew down each of your hanky edges onto the first layer of flannel. When you sew the squares together you will only be snipping the flannel, not the hankies.
Most of my hanky quilts are made with 3 layers of white flannel.
Update 10/18/15
I recently made a vintage hanky quilt for a customer and I tried something different that I will continue to do. I sewed the hanky onto white muslin instead of flannel and then layered that square with the normal middle and backing in white flannel. I loved the look and the feel of the muslin and it didn't change the fluffy seams at all. It gave the whole quilt a nice fresh sheet feel. Here's a picture:
Update 4/3/16
Check out the revised Step 12. Thank you to Judy for reminding me of this very important (previously missing) step.
Update 4/23/16
Here is my latest hanky quilt. This one I made a heart design with the hankies. I'm posting it to show what the back looks like.
Update 8/1/19
I just read through this post to see if what I had written way back in 2013 was still the way I make these quilts. I have made sooo many since then and I do everything almost the same way BUT now I find the largest hanky and I cut my muslin 2" larger. This ensures that I will not cut into any of the hankies when I cut the seams. I also always do my hanky quilts with 4 layers - hanky, muslin, flannel, flannel. No more fleece unless someone asks for that.