Those methods can yield great results, but a word of caution: Before brand names became the thing, Jewellers and other outlets received watches from the manufacturers with no brand names on the dial*. Leaving retailers to add their own. So you'll see trench watches with Mappin or Harrods, or Campaign or other retailers printed on the dial.This was particularly the case in the anglosphere, in Europe the brand was more usually front and centre. So quite the number of enamel dials out there have logos/names added after firing by printing on top of the enamel and these methods will almost certainly remove them.
*Hans Wilsdorf of Rolex was one of the first to fight to get his watch company name on the dial. You sometimes find intermediate examples where the company name is around the subdial, leaving the main part of the dial blank for the retailer. EG this Longines.