glazing information request

 

Different glazing mediums for acrylics

Hi David,

I took your first Acrylic course and I will be taking your second course Mastering Acrylics II on April 12. I now understand your comments during the course that the indirect method of painting has a lot of potential, especially since I’ve seen Rembrandt's work. It took me a year to finally figure out how I could use that method in my style of work. I use ¼ inch masonite (hardboard). I divide a sheet into standard sizes of 24x18, 20x16 and 11x14, priming both sides and edges. I started out producing a number of paintings using GAC 100, the only problem was trying not to create tiny air bubbles and I noticed that it levels out too much. So, after 25 paintings, I’ve decided to try GAC 200 to get a more built-up texture effect. I’ve done 3 paintings now and 2 of them showed signs of cracking (like the old varnish crackling effect) in just one or several spots, the size of a pea or bean. I’m not sure if it’s my technique or the product. I’m meticulous so I believe the following could have happened:
-During trowelling there was air or a drop of water.
-Board was bumpy•
-Flex in the board.
-Contamination of the product.
-Painting may not be dry enough.
I did allow the painting to dry for 24 hours before the application. I’m unable to figure out why 2 out of the 3 paintings cracked. As I have a showing slated for West Vancouver and Whistler, I’m planning on using GAC 100 again. However, if you have any suggestions I would appreciate it.

Thanks, Kurt

 

Hi Kurt,

Lets see if I got this straight: you used GAC 100 for glazing and you got bubbles, then you tried 200 and got cracks. Am I right? Bubbles are almost always caused by too much water in the mixture. Make sure your brush is dry!!! Also, foaming can occur if you are scrubbing with a thick amount of glaze medium over a textured surface, again, more likely if there is water in the mix. GAC 200 is not formulated to be used as a glaze medium and is the hardest (and therefore most brittle) of the GAC series. It is more for sizing/priming smooth surfaces because it is very sticky, like glue. It would be the most likely to crack.

Along with their regular polymer medium, which is fine for glazing, Golden has produced a number of special purpose acrylic polymers, called the GAC series. There are five of them: 100, 200, 400, 500, and, 700. Each is specifically formulated to have different properties that are useful in different applications. For example, they can regulate the paint to make it more transparent, or change the viscosity, adhesion, flow characteristics, and so on. Golden has information pamphlets that you can get at the art supply store, or you can go to their web site, to find out more about the specific properties of their mediums and their recommended applications. GAC 100 and 700 are the best for glazing (i prefer 700). Also, using a glaze to create build-up or textured effects is not effective. Not matter how much you use they will all level out. For texture and thick applications you must use a lot of thick paint from the tubes or use the various gel mediums. If there are other concerns that I have not addressed here Kurt I will need more specific information about your methods and the materials you are using...you can let me know. Hope that helps. See you in April Kurt. David