Following are a few ways you can create cloud effects in your paintings. #1 will be if you have a lot of clouds, but also a lot of blue sky, and need to mask off the clouds.(USING NO MASKING FLUID) #2 will show what to do if you have a lot of sky and only a few clouds. And #3 will show mostly clouds with a few peeks of blue sky.
#1 Lots of sky/lots of big cloud formations.
If you want to mask off clouds so that you have some freedom to wash in lots of sky, here is one way. First, tear some tracing paper in the general size and shape of your cloud. Rip strips of masking tape and tape the tracing paper to the painting ripped side out. (This is to reduce the hard-edged look that masking things off often gets.) Leslie Macracken (who is BTW a man) suggests using a knife to cut the edges of the tape to the cloud shapes. I didn't care about the specific shapes enough to try that.
After I finishe taping, I still wanted to ensure soft edges, so I applied gum arabic (slightly thinned with water) to the edges of the tape and let it all dry.
I used a wash of cerulean and French ultramarine over the sky, painting dark at the top and getting lighter toward the horizon. There is a tiny bit of pink in the horizon too. I chose these colors for two reason. One is that they both lift nicely. Another is that I planned to use cerulean as part of my gray mixture.
While the sky is still wet, I BLOTTED around the cloud edges. (I'm still trying to prevent any hard eddges that I might have to soften later.)
While everything was drying I washed in a warm wash for the ground, using quin gold and cerulean.
I removed all the tape. And I'm pretty happy with how soft-edged the clouds are.
Then I begin to shade or gray the clouds. Rules of perspective are for skies too. As clouds recede in the distance, they become smaller, less distinct, less detail. Often the tops of the clouds will be more white as the sun hits them, and the bottoms will have the shadow colors. For my base shadow color is mixed cerulean and quin burnt orange. When I wanted to cool it a bit, I added French; to warm it I adde alizarin crimson.
The painting is about 3/4 complete. I've added detail to the clouds and warmed some in the foreground, and cooled some in the background. I added some trees to the horizon line using quin gold, french ultramarine, and alizarin. The pink in the sky is alizarin. I warmed large cloud at the top of the page with a little gold to tone down the white.
WHEN YOU HAVE JUST A LITTLE BLUE PEEKING THROUGH
The top of this small sample shows a nice easy way to show little peeks of blue poking through the clouds. Wet the area you want with water. With a little GUM ARABIC in your water, pick up some blue paint and paint into the area you have wet...BUT NOT TO THE EDGE where it is dry. Paint up to the last 1/4 to 1/2 inch of the edge, and let the water and gum arabic carry the paint to the edge of the cloud. It will create a soft edge such as the top two sky areas.
At the bottom is the gray I used with a little gum arabic in the paint. You can see how the gum arabic makes it disperse differently especially on the right.
The top of this picture I put a horizontal line of gum arabic from the jar. Below that I painted some blue and let it wash into the gum arabic area.
On the very bottom of the picture I just painted blue, and while wet, lifted the small cloud with paper towel and thirsty brush. You can also drip water and create a backrun for small, wispy clouds.
