This is why I always stitch on two layers of fabric. I don't know who taught me to do this, I don't think I ever saw it written down. But just trust me.
And I encourage you to do the same, it's why when you get a Wimperis Embroidery kit you always get two pieces of fabric.
Let me explain why.
1. Your fabric should be drum tight at all times. There are couple of ways to achieve this, including wrapping the inner ring of the hoop with ribbon, but me the simplest way is to stitch onto pieces of fabric. It makes it much easier to keep the tension. And that's important because...
2. Proper fabric tension means you're less likely to warp and pull the fabric. This is especially important when starting out in embroidery, because you're less likely to know exactly how tight to pull the thread so that it's tight enough to lay flat but not too tight so that it distorts the fabric.
3. Your fabric will be less see-through if you're using two layers. Meaning you don't have to worry so much about that messy hoop butt! And it also means...
4. Your fabric will be closer to the colour you actually want it to be. If you're stitching on white cotton then using two layers means the white will be properly white. If you're stitching on coloured cotton you can add a white second layer underneath so that the coloured fabric really pops. It just makes everything bolder and brighter and a nicer surface to stitch on.
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