What does it mean to stretch watercolor paper? Why and how would you do it?

The main reason people stretch their watercolor paper, is because when it gets wet, as you paint, it expands creating cockles or wrinkles. These can make painting difficult for some people. By stretching your paper, the cockles are greatly reduced or removed completely. Whether or not you stretch your paper depends a lot on your skill level. Also, the type of painting you are doing may determine whether to stretch or not.

I rarely stretch watercolor paper smaller than a full sheet, but it is worth knowing how to do it.

There are a number of different stretching techniques  – I use a couple but not all.

Here are the main methods I know of:

Using gum tape to stretch watercolor paper

The most common, certainly in the past, was to thoroughly wet your paper for about 15 minutes. This allows the paper to expand fully. You then pick it up and allow most of the surface water to drip down off the paper.

The wet paper is then placed onto a waterproof backing board after which it is taped down around the edges. Two-inch wide gummed tape is used, which is dampened with water on the glue side. You then have to let this dry completely till the tape sticks to the board and paper, usually overnight.

This provides you with a very smooth surface to work on with minimal cockling. There are some problems with it however.

The main one is that you must wait quite a few hours for the paper and tape to dry. This means if you get the urge to paint, but don’t have some pre-stretched paper at hand, then you could lose your inspiration by the time the paper is ready.

Secondly, if you do not wet the tape enough it will not stick to your backing board. However, if you wet the tape too much, you risk the glue, from the tape, getting under your watercolor paper and sticking it to the board! This happened to me once, so I stopped using the technique not long after. I had to destroy my painting to get it off my backing board.

Thirdly, once your painting is finished you must cut your painting from the tape. You also have to remove the remaining tape from your backing board – not a quick thing to do, though I suppose if you used a waterproofed board you could just soak it in water till the tape loosens its hold. Half the tape will still be stuck to the edge of your painting, unless you cut it off, which is what I used to do.

There are many YouTube videos which show you this technique. Here is one:

Using staples

Stretched paper prior to covering staples with tape

This is like using gum tape, but instead of taping the paper to your board, you staple it — every two inches or less. This has the advantage over the gum tape technique that it is very quick, and you can start painting straight away.

I make sure my drawing is done before I wet the paper as otherwise I would have had to wait for it to dry before I could draw on it.

I also place masking tape over the staples, this gives me as nice edge once the painting is finished and the tape is removed.

As I use Gator Board — which is made of two thin veneers of compressed wood on either side of a foam core — it is very easy to remove the staples when the painting is completed.

It is important that the staples are not too far apart or when the paper dries it will be pulled through the staples and most of the benefit of stretching will be lost.

Soaking paper then drying the painting surface

For this method, you soak your paper in a bath tub or bucket for about 10 to 15 minutes. You then lift it out and lay it onto a waterproof board after which the painting surface is dried with a clean cloth towel.

Once the surface is dry, but with the rest of the paper still very wet, you can begin painting. You can also tape the edges down with masking tape if you want to have a nice border around your finished work.

This technique is quite good as it allows you to start painting relatively quickly, and the wet paper stops any cockling (wrinkling). It also permits you to keep working on your wet-on-wet passages quite a bit longer. The wet paint does not soak into the paper as much as it is already quite wet. Also, as the top surface has been dried, you are still able to create sharp edges or use dry-brush techniques.

Just thoroughly wetting the back

North Coast Sunset – I thoroughly wet the back of the paper

I often use this method to stretch watercolor paper as it is simple and quick. It allows me to get painting as soon as possible. Basically, this technique involves using a brush to thoroughly wet the back of my paper, once I have completed my initial drawing.

After wetting the back, I lay the paper down onto a waterproof surface, and I begin panting straight away. This is an excellent technique for anyone who finds their paper drying too fast. It also allows you to gently lift the paper and give it a light spray underneath to keep it damp.

To understand why this method works, you have to realise that when you paint onto dry paper the water in your paint mixture dissipates in two ways. Firstly, it dries through evaporation, however, it is also absorbed by the dry paper underneath. Because of these two processes, the painting surface can dry quite quickly, which can be a problem for less experienced artists – or when painting is a very hot environment. However, with this system, as the paper is quite wet below the painting surface, you mainly have to contend with surface evaporation — hence giving you more time to work on your wet-on-wet passages.

Using canvas stretchers and staples

This is an interesting technique to stretch watercolor paper. I found it in a book by Ewa Karpinska, where the wet watercolor paper was fixed to wooden canvas stretchers. One big advantage of this technique is that as the paper dries you can easily spray the back to keep the moisture content under control. You must be careful you do not damage the paper surface as you work however, as it effectively has no backing board.

I am sure there are other systems to stretch watercolor paper, but these are the main ones I have come across. If you know of any others, please let me know.