The way you describe the masking technique is how I do it. I do
however have another method I use for very intricate masking where
tape is not viable.
I cover the areas that are to remain high polish with Araldite. This
give me much better control
over what gets matt finished, similiar to paint masking before
rhodium. The glue when hard offers a strong enough mask for the
brush not to penetrate. I use a stainless steel pin brush to matt
finish. I use this mainly on watch bezels that have grooves in them.
I then remove the glue using boiling hot water and a toothbrush or
Hope that helps.