Topstitching a serged seam - advice needed

[SkoutSews]

I am about to start on McCall's 7874, a knit top, using a jacquard stretch knit from The Textile Centre.  I've been reading through the pattern instructions and thinking it through before tackling the job.  The main seams will be sewn on the overlocker, with the exception of one tricky right-angled section on the front where I will have to use my sewing machine.  There is a lot of topstitching to emphasise the construction lines of the top.  I usually avoid topstitching, to be honest, but I feel it will work here if I can do it neatly.

My question is, what is the best way to topstitch a serged seam?  Should I even attempt it?  Do you topstitch to catch the 'bound' serged seam allowance or press that to the other side and topstitch on the fabric alone, in which case it would be purely decorative and add nothing to the construction?

Any advice or suggestions will be very welcome! 

[Acorn]

I would definitely catch the serged seam under the topstitching - it will give a good, solid feel to the construction and I don't think the topstitching will show properly otherwise.

[SkoutSews]

Thanks Acorn.  It did seem pointless to topstitch without catching the seam allowance, but it is going to be harder.  I'll just have to be careful.

I should have also mentioned that I intend to use a coverstitch single needle chainstitch as the topstitch.  Is this advised or is it better to use the normal sewing machine? 

[SkoutSews]

Thanks Fran. You're right, the sewing machine would be more controllable and that might help the overall result.

[BrendaP]

I should have also mentioned that I intend to use a coverstitch single needle chainstitch as the topstitch.  Is this advised or is it better to use the normal sewing machine?

It depends on how stretchy the fabric is.  I suggest you do test pieces using both machines and see which you like best.  The chain stitch should be stretchier but the bigger foot will probably be more difficult to control.

[SkoutSews]

Thanks Brenda, that's a good suggestion. It was the stretch that made me think of the chainstitch in the first instance. I'll experiment!

[Bodgeitandscarper]

I did a bit of topstitching on stretch recently, but I used two needles in the overlocker, one going in the "ditch" of the seam and the other over the seam allowance, a bit tricky with my Babylock which goes like a bat out of hell!!  I think a sewing machine would stretch the seam out too much, but as has been said, experiment with some scraps.

[SkoutSews]

Now that technique would have the great advantage of producing a beautifully straight line of topstitching. It's going to be part of the experiment. Thanks, Bodge.

[Morgan]

If using the coverstitch for the top stitching and a right angle is involved, first practise the technique of turning a corner so that you're happy with your accuracy.


Then,
- Stitch the seam(s) with the sewing machine, (or treat it as a laid seam ie.  press the seam allowances of the top piece under and use washaway wondertape to place the top piece over the bottom piece)
and
- use the coverstitch to do the top stitching and finish the inside
- trim away any excess seam allowance

If using the coverstitch, overlocking the seam allowance beforehand just adds bulk and stiffness to the seam allowance.

However, if using a sewing machine to do the top stitching, then a 3 thread overlock edge finish on the seam allowances is the way to go

[Ploshkin]

I've never had a problem top stitching an overlocked seam with an ordinary sewing machine straight stitch.  I've done it on knits.   It probably helps having the IDT (even feed) on the Pfaff.  Try out various methods and see how they work for you.

[SkoutSews]

Ploshkin, thanks for your reply. Good to know that overlocking plus sewing machine topstitch works for you.

Morgan, thank you for your message about the 'laid seam' approach. That one sounds as if it will produce a neat, flat finish inside and out. I'll remember to stick with 3 thread overlock too, if taking that option.

As always, brilliant advice from TSP! Thanks to all.

[datcat23]

My sister only recently got a coverstitch.  Prior to that, all her topstitched seams were created on the sewing machine, with a twin needle and a walking foot.  And her finish was perfect.  I have a CS, and I find that while its pretty, its really unnecessary.  If you are only doing a single row of stitching, I would use the regular machine, with a walking foot if necessary.  I would press the serged seam to the stitching side, and use the topstitching to anchor it in place.  I would press the seam first, and if its bulky, I would use a roller or rubber mallet to flatten it too. 

[Celia]

I frequently topstitch on Overlocked seams, however I do use my straight stitch only machine and a longer stitch it works fine as long as the seam does not have to stretch tooo much in wear.

[Catllar]

My opinion for what it's worth is that if you've already served the seam and then you are thinking of CS'ing for the topstitch that's a lot of tiny holes through your fabric - might it weaken the seams?

[SkoutSews]

Good point, Catlar. It would definitely be an issue for the dance costumes you make, which have to cope with a lot of strain on the seams. That applies to Celia's comment about the lack of stretch in the machine topstitch too.  It's a bit of a concern. However, I'm hoping that as my top will have plenty of ease and won't be skintight, this shouldn't be a problem (crossed fingers emoji needed). Datcat, I'll look out the rubber camping mallet in case it's needed!

Due to other things getting in the way, I have yet to cut this out! Hope to make progress this week. I'll report back.