I have a 25 year old home with exterior cedar siding. It was original coated with a grey semi-transparent stain, and recoated several times with the same. What are the recommended products / process to change the color? Type of primer? Type of paint / stain to use to change color? Is painting the only way to change color?
Here is a reference from Karl Crowder's Exterior Stain Page. His experience in exterior staining far exceeds my Knowledge. So I took the liberty to gather this info for you. I hope it helps in the project you are planning.
Evaluate The Condition Of The Wood
When choosing the best exterior wood stain for your project you will need to evaluate the surface first.
After a thorough pressure washing most of the loose and oxidized stain should be removed. Unfortunately, some stain will remain under the surface, but how much is remaining? Answering this question will determine which stain to use.
Siding will usually come clean, but soffits rarely see the sun and weather. So it is possible to use virtually any exterior wood stain color on the siding, but the same color or darker exterior stain will have to be used on the soffits. Keeping to one color for the body and soffits will make the application easier. Choosing a slightly darker color is the best compromise. Only a solid color stain can cover up the preexisting stain and offer a even look.
If any sheen remains on the stained surface, only the same type of exterior wood stain can be used. This sheen is typical of oil base stains. It is my belief that oil base stains should be used over oil base stains and acrylic over acrylic. The evaluation process is very specific to each home and has to be done before the actual exterior wood stain and color can be chosen.
All of these stains are available in many colors, with custom mixed colors possible. This is especially true for solid stains. Most manufactures have dozens of colors and multiple bases allowing for deep colors. The most popular colors I have used over the years are browns and reds or combinations of these. At my high altitude, in Colorado, the inclusion of brown into any color will provide more UV resistance.