Create bright blue with oils has been a fascination of artists for centuries because of the relationship both with the blue sky to the sea. In addition, the blue pigments made were very valuable in the middle Ages and the Renaissance, since the blue had a special meaning.
You must take into account the surface and the terrain on which you are painting. IF you paint a canvas with traditional white oil, you will set a bright white surface that will allow the light to reflect through the back layers on top. The white primed canvas will remain the point brightest in a paint and paint finely layered with blue make white plays a key role in keeping the clear and bright blue.
Choosing the right paint pigment for your determine the brightness of blue. The oils are made by mixing pigments with flaxseed, walnut or sunflower oil. Prussian blue and oversea will blend well with turpentine for a quick drying or oil for a slow and luminous drying. Try mixing turpentine and oil to create a faster drying coat that will retain its luminosity. Cerulean is a bright blue pigment that will be brighter than ultramarine or cobalt blue, but may not sit so well because of the opaque and intrinsic nature of the pigment.
Be aware of how the different colors will react in an optical way. The bright yellow or white will brighten the blue by setting it at the top. On the other hand, a deep black opaque or dark under the blue, will darken it. It is also possible to put the painting in layers with a drying technique called bonding colors. When painting with blue without mixing it with oil, you allow to see more the base paint and see through patches, giving quality to the work.
Relationship to canvas
As you paint, consider the other colors used in your painting. Blue may appear brighter according to adjacent colors. For example, mixing the cerulean with white next to an opaque black mountain will make the blue appear brighter due to the contrast created against the black. Also, take into account the relationship between the blue to the other bright colors in the painting. If the paint offers bright oranges and yellows, your blue may look darker by comparison. Look at the canvas as a whole to determine the relationship between the blue and your image in general.