When I reinforced my carport, I added pressure-treated 2x4 bracing. The ends were cut at an angle, so I sprayed on a heavy coat of Copper-Green® Brown wood preservative on the exposed ends, and let them dry, before assembling the reinforcement.
Copper-Green Brown will turn wood brown. This is exactly what I wanted; the resulting color matches the brown color of the rest of the pressure-treated carport framing. Other varieties are available, including "green" and "clear".
Copper-Green is for exterior use only. Only apply it in a well ventilated area; wear a mask to avoid breathing it; and wear eye-protection while applying it. Both the copper and the napthenate are toxic, so follow the labelling to "Wash thoroughly with soap and water after handling and before eating. Remove contaminated clothing and wash clothing before reuse."
It smells nasty, and the smell lingers for several days. (The smell does go away eventually.) The smell is because the product is copper napthenate. Napthenates are aromatic hydrocarbons that can make crude oil acidic. Napthenates help the copper penetrate the wood, and cause the copper to bond directly to the cellulose in the wood. This means the treatment will last indefinitely; it will not be washed off by rain. "It is not easily lost from the wood by leaching." The Material Safety Data Sheet (MSDS) is on-line.