Frustrated with my attempts at being unable to get a perfectly straight and clean line on an unprimed canvas when using a highly watered down acrylic paint I was begining to think that what I was trying to do was actually inpossible. I can't recall ever see an artists producing work like this so this confounded my belief. I thought I would have one last go at researching masking tapes to see if I could find one that would do exactly what I wanted.
I spent quite a bit of time looking and trade sites, building supplies as well as painting forums (painting in fine art as well as a home decoration context). This led me to find two types of masking tape that may do the job I needed. I decided to buy a roll of one of the taope, 3Ms scotch 3434 masking tape. This tape (unlike nearly all others) was actually waterproof so I thought that this may stop the water seeping underneath the tape which was the problem I was having with the others.
When the tape arrived I quickly unpacked it and masked up a small unprimed cavas so that I could give it a try. I was immediately impressed with just how much more tacky this tape was when compared to the frog tape I had been using. Once I had carefully laid the tape down in perfectly straight lines I ran my fingernail along the edge where the paint would sit in order to really push the tape into the canvas.
I then mixed up some cadmium red acrylic with lots of water which I appied to the canvas with a sponge brush. Once I had soaked the area fully I then carefully removed the masking tape. I was pleasently suprised to see a perfectly clean line where the tape was as can be seen in the next picture.
I was really pleased with this and I carried out further experiments and found that I could always get a perfectly clean line when I used the tape on an unpainted and unprimed canvas. However, I later discovered that I was encountering problems when I was using the tape on top of an area that was previously painted even though that area was fully dry. The picture below shows exactly what I mean.
Here you can see that the blue layer which was painted after the red and yellow lines had dried has slightly seeped into the red a blue areas and spoiled to clean line. This was very frustrating and I could not work out exactly why this was happening. For a while I thought that the earlier layers may be still damp but even after leaving layers to dry for several days I still had the same problem. I was begining to think that I would be unable to paint on top of earlier layers which was really annoying as I wanted to be able to layer two primaty colours to produce a secondary colour in this series of works.