Fixing mistakes

Mt. Hayes and the Alaska Range, by Carol L. Douglas
Sometimes when we rework old oil paintings, thereā€™s a temptation to repaint the entire surface. The new paint looks lush and full; the old paint is dull and thin. Thatā€™s particularly true when you never got past thin layers in the first place. That old turpentine-thinned paint has oxidized. The drying leaves a pitted surface on the top of the paint, which appears chalky and grey.  
You can bring the color back up in these passages by varnishing, but you really shouldnā€™t paint into varnish or medium, no matter what you might have read elsewhere. The ā€œfat over leanā€ rule applies even to old paintings.
If your painting is thoroughly dry, you can brush a light coating of turpentine or mineral spirits over the painting. That will bring up the colors of the oxidized passages long enough for you to make your corrections. It ought to stem the urge to repaint the whole thing. Of course, if large areas of your paintings are oxidizing, youā€™re not using medium correctly.
On Friday I shot an extremely short video of myself changing the color of the traps in a tree line. I sent this to a reader who was wondering how much paint to use in this correction phase. It doesnā€™t have much in the line of production values, but it might be helpful.
The painting of Mt. Hayes and the eastern Alaska Range was painted near Delta Junction, Alaska. It was early in our trans-Canada trip. Although it appeared surface dry when I wrapped it, the thicker white paint in the river and sky squished and flattened under the weight of subsequent paintings.
This was a simple resurfacing jobā€”and that was a very good thing, since I have no reference photos. It also gave me the chance to adjust the color of the Tanana River, which looks like light chocolate milk, itā€™s carrying so much silt.
Lake of the Woods, by Carol L. Douglas
Iā€™d realized after I left Lake of the Woods in western Ontario that Iā€™d never actually finished painting in the sky. This was a very simple fix, but I used the moment to add a little warmth to the water in the foreground.
In the last painting, I corrected a lie. Iā€™d intended to paint a house surrounded by fields and a windbreak, but couldnā€™t find the right combination of side road, farm and fields. In real life, my subject was fronted by a low waste area of reeds but Iā€™d edited that out.
Windbreak, by Carol L. Douglas
When the glaciers from the last ice age receded, they left behind millions of shallow depressions. These wetlands are known as ā€˜prairie potholes.ā€™ They are significant resources for plant and animal life and support millions of breeding waterfowl, whose numbers are being threatened as the potholes are drained for large-scale farming. I really shouldnā€™t have excised them from the one scene in which they appear, and it makes me consider whether I want to add a studio painting that does the potholes justice.
I expected that deleting the field and reinstating the reeds would take me a long time, but it was done in fifteen minutes or so. I will probably incise a little more texture into the reeds, but itā€™s never going to be my favorite painting.