The Upholstery Forum

New sewer here - I recently sewed up a sample seat cover bottom and everything looked fine until I looked closer. I found that when sewing a panel with skrim foam to a panel without, it seems that one of them moved. I would have to make some other sample parts to tell if it's the top or bottom that's moving but I do remember my witness marks ended up moving about 1/4" in about 12-16". I'm assuming it has to do with the presser foot tension? Could use some suggestions on what to look for and how to adjust for it.

Could you post a photo? Is your foam glued or stapled to the panel?

Not much to take a picture of, it's all together. I didn't glue the foam to the vinyl, only glued the muslin on the bottom of it and then sewed it around the perimeter of the vinyl piece.

@fibersport , you following some marine tutorials?

BigRig - Not sure what you're asking.

Were your witness mark before or after the upholstery and foam were sewn together?
The upholster shrinks when you sew foam to it.

The witness marks aligned before I stitched it together, they moved during the sewing process. My guess is that one of the layers was slipping under the foot.

Whenever I've done anything that required scrim foam such as pleating or diamonds I glue the vinyl to the foam. do all the pleating, then cut the piece to size.

When pleating, everything "shrinks" a bit as the foam compresses.

If there is slipping under the foot as you say I would expect you alignment markings to get progressively worse as you sew further.

I'm just glad I made a practice cover, better to ruin some vinyl than the leather I have for the final ones. I think what made it worse is that one side was sewn from one end and the other from the opposite end, any creep was then just made worse since I sewed from opposite ends. I'm thinking I should probably make more witness marks so I could watch it more often and be prepared to pull one piece or the other. I'll give the glued up approach a try too, it can only help -

making pleats or diamonds if you have Johns courses make sure to use the mark up sheets so you know the measurements to start and finish at . it will save you a headache later.

@fibersport , that is far too much movement foam or not. I use clips and stay with my alignment (witness) marks always. A slight shift is ok but there is a lot of fabric adjusting to do when sewing. Keep those marks lined up.

You can use a "plyer stapler" to baste the material together while sewing, easy to remove the staples later.

When I was stitching it up, I really didn't realize how much things were moving. Had I realized it I might have stapled it. It was odd that there were a lot of witness marks on one piece but only two on the other. Call it inexperience -

@fibersport . each time you get better than the last. I sew covers for a major seat cover company everything has to be spot on.