All mediums can be easily corrected, except watercolor. This alone scares many artists away from using this medium, especially those that like to nit-pick. Yet the enchantment of watercolor is the spontaneity and “happy” accidents. This unpredictability is what can create enchanting effects. This tutorial will give you some insight on how to correct watercolor as much as is possible. First I’d like to give you ideas on how you can diminish the need to correct.
A. As a rule of thumb do not over-layer wet paint on top of dry paint unless it is to sculpt out accents and darks. This will result to “scabs” which is very unpleasant in this medium. In any case if you wish to add paint on top of a preexistent layer, wet the surface first.
B. Resort to non-staining pigments such as Hooker’s Green and Alizarin Crimson and use substitutes that can be easily sprayed out.
C. If an area is detail sensitive such as the eyes in a portrait, apply some Lifting Preparation from Winsor and Newton first. This will block some of the fierce adherence of the watercolor to cotton fibers of the watercolor paper. That will enable you to remove paint more easily so you can start over.
D. Avoid glazing unless absolutely necessary, especially on cold-pressed paper. Glazing will deteriorate edges and detail and can lift part of the first layer off which will mix with the new layer resulting into mud. Rough paper gives you more tolerance but I still do not recommend it.
E. Keep a small sheet next to your painting to run tests before going directly to the paper. That way you can adjust your color before it is too late. Remember watercolor dries lighter than it appears when wet.
I have found that the easiest and best way to remove watercolor is by using a garden spray bottle that has a jet stream capability, which means that when you squirt the water there should be a decent thrust, somewhat like a power car washer connected to a garden hose. I recommend that you do not scrub off the paint because the paper will start to peel like bread crumbs. There will always be a ghostly image of what was there earlier, but this can be easily covered with the new paint.
If, after all these suggestions, you do not resolve the problem, implement pastels, especially PanPastels, a fairly new medium, which are extremely compatible with watercolor. In fact you cannot even detect its application. The reason for this is because the pigments are more pulverized than ordinary stick pastels and the applicators force the very fine particles right down into the fibers. You can freshen up an overworked watercolor. You can add delicate highlights to trees and bushes. Some purists argue against adding a dry medium to a watercolor, yet they allow for gouache and acrylics just because they are liquefied with water. They are still opaque so, in my view, where do we draw the line? You owe it to your viewers to give them the most beautiful rendition you can even if it means adding other mediums. Just mention,“Mixed Media” if the need arises.