Patching holes in the knee area can be tricky because you have to contend with the depth and narrowness of the leg barrel. I'll show you what I do and hopefully it will make your next attempt at repairing these holes less painful and more rewarding.
fabric scraps for the patch
double-sided adhesive interfacing
sewing machine with zigzag stitch, removable platform is also helpful.
thread to match jeans you are repairing
Step 1: Choose Patch Material
1. The hole. It's a good one. Typical knee slit, with the telltale sign of reckless abandon; multiples washings long after the hole was born.
2. Do you want to patch it with scrap denim or khaki? After all, it is A HOLE, which reveals skin underneath. : D. You could get creative and patch it with all sorts of things, but for this particular job I wasn't explicitly given the "Go Wild!" directive.
3. Measure width of hole, add 2" to that number. All the extra gets cut away after and you don't want to later regret being initially frugal with the patch size.
4. Now measure the height of hole and add 2" to that number as well.
5. Pink(or use reg. scissors) your patch material(s) to that size.
6/7. I tried both and decided on the denim. I used the wrong side to match the lt grey a bit better(I didn't have any scraps of faded black jeans)
Step 2: Prepare Hole and Patch
1. Cut away most of the strings. You can leave some on the horizontal stretches for style, but they may get caught on objects later if the span is too wide, so take that into consideration.
2. Turn jeans inside out.
3. Prepare a piece of double-sided adhesive interfacing, just smaller than your patch size, and place onto right side of patch(part that will be facing outward) It should grip it and stay put.
4. Flip patch over onto hole, centering so that patch edges extend evenly over tear.
5. Iron on high heat, no need for steam. Move the iron slowly over the patch, applying the full heat to all areas of the patch. Twenty seconds should be sufficient. The adhesive of the interfacing won't get stuck to the jeans on the other side of the hole. It is very lightweight and will really just disintegrate with the high heat.
6. Turn jeans right side out.
Step 3: Set Up Your Machine
1. Choose a thread that is similar in color to the jeans you are stitching onto.
2. If you can, remove the platform of your sewing machine to expose the narrow, sleeve arm.
3. Choose a zigzag stitch. This will offer a little flexibility and give you a wider path in a single pass.
4. Now feed your pants onto the sleeve arm, foot hole first. Smoosh them as far right as you can, ensuring that you give yourself enough work space without the bunched up leg interfering.
Step 4: Sew!
1. Start at the back and begin sewing, stitching the first row under, or to the right of, the tear. Begin sewing a good .5" before the tear starts.
2. Align the toe that is left of the needle with the edge of the tear. This is a good guide to make sure you grab enough fabric of the jean that is still undamaged, but not too far away from the tear so that it could get larger in the future.
3/4. Finish sewing that row about .5" after the tear stops, and cut your thread.
5. Repeat process, now above, or to the left of the tear. Again starting and ending .5" outside of the tear edges. Pull all thread tails to back of work if you don't have an auto-cutter.
Step 5: Finishing Touches
1. This is how it should look from the front, and
2. the back. Trim any loose tails, after tying together.
3. Gently pull away interfaced patch just before you get to the sewn-down portion. After wearing and washing a few times, this will pull away on its own, so better to have some control over this and take care of it now.
4. Use pinking shears and carefully cut around,creating curves rather than sharp corners.
5. Give it a final, hearty press with a hot iron and turn right-side out.
6. Embellish if you'd like! (I saw a few splotches of green paint and covered these boy jeans with some uber masculine finishing touches. I'm sure he'll giggle for a bit, then remove and stick them on the homemade Valentine's Day card for his girlfriend.)