A washi tape works exactly like a masking tape but this is offered in a lot more sizes with fun textures, patterns, and colors. You can even match your washi tape with the design of your canvas so it'll look cuter once finished.
A canvas using double sided adhesive normally extends the tape adhesive past the edges of the pattern. Because of this, some dust and small particles can stick to the sides of your canvas. You can use the washi tape or masking tape to cover the excess adhesive on the sides of your painting to prevent this from happening.
As Home Craftology is now using poured glue canvas, this shouldn't be much of a problem for our customers. Poured glue doesn't extend as far as a double sided adhesive does. However if you feel that there's a need to still use one, please do so as you know what works best for you.
Another useful trick for portioning your poured glue canvas is by using washi tape. With the plastic covering still in place, you create your own grid lines using washi tape. The size of your grid lines would really depend on your preference. Once you're ready to work on a section, just cut off the square grid that you'll be working on. You can cut the edge of the plastic cover and peel off following the washi tape as markers.
Here's a sample photo from our customer Sara wherein she used washi tape around the edges of her canvas.