Is it possible to glue little parts on painted pieces ? if impossible, do you really have to mask every place you will glue something on ? My question is for little pieces, like cockpit sides and floor details, or pieces in landing gear bays.
Although small parts may initially adhere where there is paint, they will inevitably fall of after a short time. With regards to what you do to get around this, it really depends on how easy the area will be to clean before fitting “little piece”.
In a few circumstances masking may be preferrable, but in my experience it is easier to paint the part then remove / scratch away anything that is going to get in the way of gluing additional parts on. Needle files are very useful for clearing holes out, as landing gear may typicaly be fitted into.
On some occasions, dependant on the location / size / shape of the area I will use small bits of Blu-Tak / Silly Putty to cover mounting holes / areas - it’s far easier & quicker than masking as such.
CA glue will stick small painted parts on without effecting the paint (white oxidization residue when cured may have to be touched-up) *This is only as strong as the paint under the part. If it does break off it will bond the paint and the part will break away with a paint chip on the plastic.
For aircraft with delicate, breakable bombs, drop tanks ect. I like to use white wood glue. It will not lift the paint if something gets knocked off and drys clear / flat. Basically its a good hold yet will break away before something gets damaged. Also this glue can be thinned with any acrylic thinner (Isoprople, water, demineralized water) and brushed into the seam, good for small difficult gap filling.
In addition to scraping, for some small parts I drill a tiny hole in the painted surface with a small (maybe about #62-#70) drill. Not deep, just enough to get through the paint to raw plastic. This is usually enough for very small parts and is easier than scraping. For oblong parts I drill a couple of such holes.
I have never had any problems with this. However, I am extremely delicate with my kits. I love the drilling idea suggested…also, simply sanding a tiny spot should do it. Another suggestion would be to pick out the small details with a brush and Vallejo acrylics.