Follow the weakest material
Use the care guidance for the most delicate part of the repair, not only the original denim. A printed patch, dyed thread or fine backing may need cooler water or gentler handling.
Turn the garment inside out when that protects the stitched surface and avoid harsh agents that can weaken fibres or change the thread colour.
Dry without forcing the shape
Let the garment dry in a way that supports the repair rather than stretching it from one wet corner. Smooth the patch flat while damp if that suits the fabric.
Avoid high heat unless the complete material pairing has been tested. Heat can change dimensions and make a previously comfortable repair feel tight or puckered.
Inspect after real use
Look for loose edge stitches, new fraying, thread abrasion and thinning beside the patch. Early maintenance usually needs fewer stitches and less fabric removal.
Store the garment without sharp folds directly across the repair when possible. Let the visible mending age with the denim and add support only where the textile shows a genuine need.