Hi @suzannehall,
Thank you for your question about repairing some water-damaged architrave behind your kitchen sink.
The problem you are experiencing is that your architraves are made of MDF, which is not a suitable product for use around liquids. It is essentially heavily compressed timber fibres, that act in a similar way to cardboard when they get wet.
You can just tidy up the flaking paint by giving it a light sand, then prime the damage with a suitable interior primer and paint with enamel paint, but the problem with doing this is the architrave is still MDF and is susceptible to water damage. It will be protected, but over time the issue will reoccur.
To fix the problem once and for all, you would need to replace the MDF with timber architraves. You should be fine to just replace the bottom piece of the architrave as the sides and top shouldn't really get any water on them.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
