You scuff up existing paint for two reasons. First, you want to get rid of any oil, grease or dirt trapped in the top layer of paint. This is the stuff that cleaners and degreasers can't get off. The second reason to scuff is to set up a physical bond for the new primer and paint to adhere to. You want to give the old paint some tooth so the new sticks better.
Hope this helps you in deciding complete exterior paint job, or partial trim only exterior paint job, saving painting costs when you can, from your local area painting contractor.
The lite version of Galkyd is simply thinner. I use it more than the other. I love it. Paintings I did 16 years ago using Galkyds look as pristine as the day I painted them. You'll also need a canvas and some paint. I buy a tube of red, green, blue, purple, yellow, brown, white and black. I prefer what's called Ivory Black and a soft mixing white as you'll add white to a lot of different colors to make lighter versions. From these basic colors you can make any exotic color by mixing them in combination's. Be creative and experiment. And don't be afraid of color, because color is the most popular in museums! The bright paintings are historically the crowd favorites. As for color variety from these basic colors, mix red and white to make pink, mix yellow with green to make lime green, white with blue to make light blue, white with black to make gray, etc. Use your common sense and play with it! You'll also need pencils, an eraser and some Turpentine or Turpentine substitute. Keep your brushes soaking in it in a plastic cup to keep them clean and ready for your next color choice.... and to keep them from drying out.
Materials and their application, every paint manufacturers paint will vary. If you are freshening up old walls and painting back to the existing color, the product doesn't have to be high end or have good coverage. If you need to paint a dark color over light color or light color over dark, you may want to consider purchasing a top quality paint to avoid multiple coats. I suggest Valspar, Pittsburgh or Benjamin Moore top of the line wall paint. These brands work well for straight out of the bucket use and are application friendly. Sherwin Williams is not my first choice because the coverage is poor and you will have to apply multiple coats but, it does apply, fluently. If you find a product does not apply well, maybe it is to heavy and/or sagging on the wall, you may need to thin the paint with a little water, this will reduce the coverage but make the paint flow better and lay down nicer on the surface. I do recommend latex paints for all applications, these days a good high end latex is as good as oil paint and your tools clean up much easier, it will also be less harsh on the respiratory system. The only situation I recommend oil paint, is as a primer/stain blocker over stains that "bleed" through the paint. You can get a stain blocking oil primer in a convenient spray can and spot prime any trouble areas before painting and in the case you need to prime all of the wall due to smoke or water damage, I recommend getting it in gallons and rolling it on where the stains are present. Don't forget proper ventilation and/or a respirator when using the oil based primers!
If paints have been allowed to stand and hard lumps or skin have formed, the skin or scum should be removed, after which the paint can be stirred and strained through screen wire or through one or two thicknesses of cheesecloth.
First consider the size of the painting. The more impressive the subject, the higher the emotions it appeals to, the bigger it is. Religious, mythological paintings are often huge - their massive energy makes you shiver. It is pretty understandable with figurative paintings like Rafael's "The Sistine Madonna", and more subtle with color field paintings of Mark Rothko. People are often overwhelmed with religious tremor in the presence of his artwork, and the size factors in. Also, the subject often calls for larger canvases - battle scenes need space and cannot be fitted into a smaller painting, while some subjects will get lost unless depicted in a smaller size.
When all of the spraying is complete, its time to remove all masking tape and paper and start touching up your entire home. This step is pretty time consuming because this is the final stage that really makes your home look good. The more time you spend here, the better your home will look.