I made a denim rag quilt for my sons. I backed them with heavier LQS cotton fabric and no batting. Denim quilts are very heavy and take forever to dry when washed. They do stand up to a lot of abuse which makes them good for a kid or guy quilt. I would recommend backing with lighter weight fabric and do a very simple stitching design. You have a lot of seams to sew over---make it easy on yourself.
Looks very nice in your picture.

Chris

You might want to practice with two layers of denim...and your batting, if you are using any...and see how it feels to you and your machine. As for quilting, I would go with something simple. It won't matter how it looks on the back at all. Probably your thread won't even show if you use a navy blue. Beautiful quilt, by the way.

Dina

My very first quilt was denim using our old jeans. It was for my daughter who was in HS. It started out 10" squares. The back was a lighter weight denim and I tied it off. Sounds good, but by the end I had fought that denim, the squares were wonky, my fingers were sore from tiring with red yarn, but it looked mighty good to me! My daughter is 30 today and the quilt is doing fine. Denim will live forever and is heavy without batting. I didn't do anymore quilting until a year ago.

Wow! Thank you all for your replies - I hadn't expected such an amazing response. I have read all answers and there is so much useful information. I am pretty committed to keeping the denim backing - it's not a very heavyweight backing but I have sacrificed 4 fingernails in the process of pinning it all together! So...what I have decided to do is to make up a sample piece and have a practise with my machine to see what it can cope with. I shall arm myself with heavy thread and strong needles and see what happens. Unfortunately, I can't take up your suggestions for where to buy supplies as I am in the UK but I can probably source everything here - the internet is a wonderful thing! I am more confident of trying to quilt a geometric pattern so will probably try the cross-hatching. I'll let you know how I get on. hopefully my son will still be a teenager by the time I finish it:)

I made one for my son and used denim on the top and no batting just a good flannel on the back and it was plenty heavy and warm. I just stitched around each block and it was fine.

I made a denim quilt for my son and put a flannel back on it. It is warm and not as heavy as a denim back would be. I would just do an overall pattern like a stipple or maybe a cross hatch pattern on it for the quilting.

Remember to use a denim needle. Tks. G

Good advice above. I made those before - very heavy. Warm though. We just tied knots - no batting - light weight backing on one and heavy on another for a picnic blanket. You already have it pieced so you know about weight. As far as the sewing machine goes I have seen a bent shaft on a vintage sewing machine because someone tired to PULL something very heavy through the machine. Possibly they got a jam and then pulled something through - usually the needle will break. I used to make tents. To get heavy stuff through the machine. Put the machine on a big table or put another table next to your sewing table Roll or fold the fabric so it will go in the machine with out hanging off the table. I've even used a roller cart to put the bulk of the material on and had a helper managing the cart as fabric goes through the machine. You can re-roll to do the other side.

I would skip the quilting altogether and simply tie it with cotton yarn.

It has to be heavy. Keep it very simple. I think it will make you happy.