There are many experts out there on the act of collaging and they may have a different way of doing things than me, but I am going to share my techniques anyway.

I like adding photography to paintings to express a certain 'vintage' feel.  A moment captured in time that is then incorporated into my work.  This is not the same as just wanting to add a flavour of realism.  It is more about wanting the impact and message that can only be said with a photo.  When this is desired I make sure to use images that either I have taken myself or I have physically collected on site of what is being painted.  Most of the time, it is photos that I have taken and printed off on my home printer.  

This is a close-up of "Kiosks line the sidewalk of New York City China Town".  Or something like that - I can't remember the full stories that make up each of my painting titles.  Stories often change every time you tell them, so that's ok.

Back to the subject - this is a close up of some collage.  I combined the use of Chinatown newspaper collected on site along with a photo I took of people walking on the streets while in Chinatown.  The combination of the two help give the painting more depth.   The photo and collected memorabilia from site help to tell the story and give the viewer more to examine.  

It is important to layer collage with the painting and drawing.  The photos or other collaged pieces should not stick out like a black beetle in white rice.  Feathering, painting over edges, extending the lines in photos with drawing, overlaping collaged elements and overall compositional placement, are all techniques that should be used to incorporate collage into paintings. 

I only use collage with water based painting mediums becuase of the gels and other glues available in acrylic lines.  I have not figured out a way to incoporate collage with oil based paints.  Maybe someone out there has some tips on this practice for us.  I will stick to waterbased to play it safe.  Golden Acrylic Gel medium in 'gloss' is the strongest of all fixatives.  It will glue on all types of objects with varying surfaces and if applied without too much excess, it will dry clear.  Dry gel is flexible within reason, but make sure your painting does not get too cold or the gel will crack when moved.

When I am just gluing on newspaper or regular weight papers I use Modpodge, a cheap colloge glue from craft stores.  It glues extremely well and does not add weight, texture or bubbling in the papers.  You can get this glue on top of the image and it won't seal the fibres, allowing paint to be applied.  When you use gel, the fibers on top of the image are often sealed and it is then difficult to layer paint on top.  Deside which medium to use depending on your desired result.

Almost anything can be collaged into paintings - this is just one small area and technique - more are to come.  sign-up for an RSS feed to catch it all.  Post your comments if you dare.