Principles of Manufacturing Copyright © Texas Education Agency, All rights reserved 1

Finishing is the application of a protective coating to a project. This is a fun and easy way to transform a project into a beautiful piece of usable art. 2 Copyright © Texas Education Agency, All rights reserved

The following slides will explain finishing the different projects produced in manufacturing labs. These projects could include:  wood projects  metal projects  plastic projects 3 Copyright © Texas Education Agency, All rights reserved

Wood takes the most steps to finish. Metal is usually painted a color of your choice. Plastics will be polished to a luster with a buffer and polishing compound. 4 Copyright © Texas Education Agency, All rights reserved

 sandpaper  steel wool  brush (bristle, foam, china bristle)  rubber gloves  dust mask  soft dustless cloth  stain (color of personal choice)  primer  paint (can or spray)  oil finish  clear finish  buffing compound 5 Copyright © Texas Education Agency, All rights reserved

The best finish is begun by sanding all surfaces of the wood project. A stained or clear finish will magnify any surface flaws. 6 Copyright © Texas Education Agency, All rights reserved

This removes all the machine marks or cuts made while producing the part. Always sand with the grain of the wood. Sanding across the grain will scratch the wood. 7 Copyright © Texas Education Agency, All rights reserved

Start sanding with a coarse (80 – 100 grit) of sandpaper if you did sanding before assembling. The planer that smoothes the surfaces of the wood leaves tiny cup cuts on the surface of the wood. The coarse sanding will remove these marks. 8 Copyright © Texas Education Agency, All rights reserved

Coarse sand until the machine and saw cuts are removed. Use medium (120 – 180 grit) sandpaper to remove the coarse scratches made by the coarse sandpaper. 9 Copyright © Texas Education Agency, All rights reserved

When the medium sanding is finished it is time to use the smooth 220 grit sandpaper to fine sand the wood. These sanding steps will allow you to put on a smooth finish. 10 Copyright © Texas Education Agency, All rights reserved

Place the brush in the finish or paint about 1/3 the length of the brush. Brush from the center of the surface to the edges. Use long strokes with the wood grain. Lift the brush slowly when you near the edge of material. 11 Copyright © Texas Education Agency, All rights reserved

On large panels start on the back side. Do not reach over wet finish or paint. When painting vertical surfaces start at the top, brushing to the bottom. Use a different brush for each kind of finish. (stain, clear finish or paint) 12 Copyright © Texas Education Agency, All rights reserved

Staining is adding color to the wood to bring out the wood grain pattern. 13 Copyright © Texas Education Agency, All rights reserved

Select the color of stain that you like. Test stain color on scrape piece of wood to see the true color you will be using. Clean the surfaces to remove dust by using a clean, lint free rag. Apply stain with chosen brush or rag. (wear plastic gloves) 14 Copyright © Texas Education Agency, All rights reserved

Allow stain to dry for 5 to 15 minutes. The longer it stays on the wood the darker the color. Wipe off excess stain with a clean rag. Allow the stain to dry overnight. 15 Copyright © Texas Education Agency, All rights reserved

Apply finish in a well ventilated area. Wear a respirator and eye protection while finishing. Use a china bristle brush and brush on a thin, even coat; not a thick heavy coat. Allow the finish to dry for 12 hours between coats. 16 Copyright © Texas Education Agency, All rights reserved

Apply two to three coats of finish, building up a thicker, more protective coat. Sand the finish lightly with 220 grit sandpaper between coats to smooth the surface and remove any imperfections in the coat finish. 17 Copyright © Texas Education Agency, All rights reserved

The preparation for finishing will have to be completed before you start to prime. Clean the surfaces of the wood with a clean, lint free cloth. This removes any dust left from sanding. 18 Copyright © Texas Education Agency, All rights reserved

Apply a coat of water base primer to seal the wood. This allows the paint to cover the wood grain quicker. Allow the primer to dry. Check the container for drying time.( usually 30 minutes) 19 Copyright © Texas Education Agency, All rights reserved

Brush the paint on in long, smooth strokes. Start in the center and paint to the outside of the surface. Clean any drips with a dry brush (a brush that has painted the surface and needs to be reloaded with paint) 20 Copyright © Texas Education Agency, All rights reserved

Allow paint to dry 12 hours before recoating. Apply two or more to achieve the effect you want. 21 Copyright © Texas Education Agency, All rights reserved

Shake the can well to mix the finish or paint. Hold can 8” to 12” away from the surface and move it parallel to the surface. Spray so you will not reach over a fresh coat of finish or paint. 22 Copyright © Texas Education Agency, All rights reserved

Metal should be sanded smooth. Sandpaper for metal is called wet and dry paper. ( grit) The finer grit used the higher polished the metal will get. For painting you will need to sand with 350 grit. 23 Copyright © Texas Education Agency, All rights reserved

Most metal projects could be spray painted. Some projects could be polished and sprayed with a clear finish. 24 Copyright © Texas Education Agency, All rights reserved

The edges of the plastic will have to be sanded using at least 220 grit paper. The finer the sandpaper you use the less buffing you will need to do. A buffer is used only for plastic to keep metal bits in polishing wheels from scratching the plastic. 25 Copyright © Texas Education Agency, All rights reserved

Apply a buffing compound to the buffing wheel. Use the bottom edge of the wheel to buff. Be careful with the corners. They can get caught in the wheel and it will jerk the plastic out of your hand. 26 Copyright © Texas Education Agency, All rights reserved

Websites for finishing and Painting ing.html wood- finishing/?WT.mc_id=BasicsofWoodFinishingMarquee projects/trim/staining-trim/wood-finishing-tips 27 Copyright © Texas Education Agency, All rights reserved