Can a manufacturer work from my own tech pack and size chart?

Working from your tech pack

Yes. If you already have a tech pack, we work from it. The first pass is a practical check rather than a rewrite: whether the fabric specified is available, whether the measurements are internally consistent, and whether the decoration technique suits the material chosen.

The size chart is treated the same way. Sizes can be mixed within one colourway, so the chart is applied across the colour group rather than per size, and each colour remains its own order for cutting, dyeing and finishing.

Where something in the pack cannot be produced as written, we say so before sampling rather than after. A fabric substitute, for example, changes the weight and the shade, which means the wash result and the approval have to be repeated, so it is cheaper to raise it at the start.

You keep the approved sample and size set afterwards, which is what makes a reorder consistent. Reorders carry the same minimum as the first order, so keeping the specification on file is what protects the repeat.