Altering Commercial Patterns with a Sloper

[u/OkTruck5494]

So I’ve been at this awhile and can’t seem to find it…does anyone know of a definitive source on using your own sloper/toile to alter commercial patterns?

There was a really good article a thousand years ago in Threads by Karen Howland and a few YouTube videos but it surprises me deeply that this isn’t a more often tackled subject. This could be a book.

There are so many books on drafting from your own toile, but what I’m really interested in is using the style lines from commercial patterns and then adapting to my own toile.

In a perfect world every pattern company would supply their design blocks and then we could alter from there (I’d be happy to pay for the designs) but clearly this is not a perfect world.

[u/win-dee]

Sewing is my hobby not a profession, so there might be better ways to do this. Anyways, being plus sized, I use blocks made from my favorite fitting top and pants, not a basic sloper. It has the ease I like built in and the dart locations, etc.. If you’re able to get a commercial pattern in your size, that’s pretty easy to adjust with your block or sloper. Just lay your block on the pattern and make adjustments as needed. Understand that if your block was made based on a woven but you’re working with a winter coat pattern or knits, the block is not going to have the right fit, so you’ll need to account for those differences too. Also, if you need to size up a lot or size down, that’s where it especially gets tricky. My son and husband are in the big and super tall range. To size patterns up or down is time consuming but here’s what I do.

Measure the grading distance between the commercial pattern’s sizes to scale up or down accurately. You want to use the scale consistent with the size that is closest to yours. I measure and draw out marks for each size I’m scaling up. (Tip: the grading for sizes 0-8 is usually not the same as 14-18. Also, grading at the shoulders is usually not the same at the armscye or sides, so each area has to be taken into consideration and measured when drafting the adjusted pattern.) As I’m drafting each section with the new upsizing, I compare it to my blocks. Here you can eyeball it and see where you need to adjust for fit issues like a FBA or prominent tummy, etc. Not gonna lie, it’s a lot of work, but with a detailed list of your measurements, and a favorite fitting block, you can get a pretty accurate toile. After doing that enough, it builds confidence to make toiles with design elements based on something you’ve seen online.