Leave the moldings in the installation room for at least 48 hours, without removing them. Maintain a stable temperature, avoid excessive heat and humidity. This step prevents future warping of the wood. Make sure walls and ceilings are clean, dry and dust. Repair imperfections: fill holes, smooth uneven surfaces. Remove the wallpaper from the molding attachment points. Apply an undercoat if necessary. Proper preparation guarantees optimal and lasting results. Take the time you need for this crucial step. Fill knots, holes and cracks with wood filler if necessary. Let it dry. Sand to obtain a smooth surface. Apply a primer to all sides of the doorframe molding. Installation height: generally between 70 cm and 1.10 m from the ground. In some cases, the picture rail can be installed at 2/3 from the ground to install very high base frames. Draw a level line on the wall at the desired height. Cut the picture rail to the required length. For 90° right angles, make 45-degree cuts on each piece of picture rail (caution: use a protractor if the angles are not 90°). Apply polyurethane glue to the back of the picture rail. Position it on the drawn line. Fix with headless nails every 50 cm, alternating top and bottom. Make an acrylic joint between the wall and the picture rail, between the different pieces, and fill the holes in the tips. Lightly sand the surface for better adhesion. Use a quality wood paint suitable for the type of wood (hardwood, softwood, etc.). Apply two thin coats, sanding between each application. Allow to dry completely between applications. Use the material adapted to the profile of your picture rail: small roller or fine brush. Use the same finish or color as your baseboards and walls for a unified look, or a different color to highlight the feature. Coordinate the style of the picture rail with that of the other moldings and furniture