The certificates were obtained at training institutes in the Netherlands and abroad. Like at the  RCE  (State Cultural Heritage) Amsterdam. And also at  the SRAL Foundation  in Maastricht. Abroad at  IAP  in London. But also at  INP  Paris. Finally, this is also possible with the association Restauratoren Nederland . Marjan specializes in cleaning unvarnished and varnished oil paintings. But certainly also unvarnished acrylic paintings. Marjan cleans according to the New Cleaning Methods, developed by Richard Wolbers . She is currently investigating the possibilities of cleaning acrylic paint with micro emulsions. Also introduced by Wolbers in painting restoration. That is why in August of 2014 she attended the CAPS ‘Cleaning of Acrylic Painted Surfaces’ workshop. This was taught in Ottawa at the  Canadian Conservation Institute.

This aroused Marjan’s interest in the influence of the tropical climate on oil paintings. Because the temperature (T) is many times higher in the tropics. And the humidity (RH) is also high all year round. Marjan restored in Jakarta no less than twice. These were paintings by Indonesian artists such as Affandi, Sudjojono, Lee Man Fong and Hendra Gunawan . 

Marjan de Visser also restores paintings on  Curaçao.  She worked there four times from 2005. The first time was at the invitation of  Stichting Landhuis Bloemhof , for which Marjan treated the modern art collection. Other commissions included two 19th century portraits of Landhuis Rooi Catootje and the Jewish Cultural Historical Museum.