Hi Mario --
Coloring bottles: Here's what I did ...
-- Spray the bottle with a light coat of mat finish to give some "tooth" (surface) for coloring
-- Apply diluted Vallejo (or Reaper) acrylic INKS ... the inks are transparent, so this will work well. Note that some ink colors are more intense than others, so you'll have to experiment with the dilution ... start light and add additional layers of color if needed.
-- Also note that the Vallejo and Reaper inks are MUCH thinner / more transparent than the artists' inks that we use for staining wood, etc.
-- Apply labels or decals if desired. Thin paper labels can be applied using Vallejo mat or satin varnish as an adhesive
-- Finish up with a clear coat ... could be a spray-on gloss coat, a brush-on satin or gloss coat or maybe Future Floor Wax (haven't tried that, but it's popular among modelers for a clear, smooth coat)
BTW, Using the Glaze medium with paints gives a "somewhat transparent" layer than can be (very) useful in adding color/shading to models, figures, etc., but the pigments in the paint are still opaque and just getting spread thinner. The Glaze medium will probably work well with the inks, but I haven't tried that yet. Using the base coat of clear on the bottles allowed me to simply dilute the inks with wet water and apply that way.
55n3 Dead Mule & Sinagua Railroad
Chambers Gas & Oil -- structure build