Hope this is not too far OT, but it is DIY & is a problem that some contributors to this group may have the knowledge to answer.
Dry cleaners often offer the service of putting permanent creases in trousers. IMHE these last a very long time, surviving many ensuing washes. However the only home crease treatments found in shops so far are starch sprays for use during ironing and resulting creases disappear very quickly (2 days or less).
Hence Q: how can you replicate by DIY the permanent crease produced by dry cleaners?
If it matters the nub of interest is mainly a treatment for cotton material rather than artifical fibres (polyester, terylene, rayon etc).
TIA