Rubbing and Polishing for High Gloss Finish.

The rubbing process is the other method to make the high gloss finish. It is the finishing process on the finishing layer to create the glossy look. To reach the high gloss finish, we can actually do with a high gloss top coat. After a certain layer of clear coat and enough film built, we can apply a high-gloss top coat to make a high-gloss finish. But we can get a better-looking high gloss finish with the rubbing process. The rubbing process is the process to finish the finishing layer to make the perfectly flat and smooth surface. We already posted an article about the rubbing process in our previous article: rubbing and polishing. While in this post we want to share about the high gloss rubbing process in more detail with step-by-step explanation and video application.

Preparation of the finishing layer.
 

To do the high gloss finish rubbing, we need the good preparation from the finishing film. The finishing layer surface needs to be even and flat. The finishing also must have sufficient thickness and completely dry coating film. For the NC finishing system, we normally do rubbing minimum 24 hours after the last top coat application. While for the AC or PU system, we need to wait for 3 or 4 days to let the coating dry completely. 

 black paint finish panel

The materials and tools 

• Rubbing Machine.

It is a 30 lb. double pad sanding machine. It is needed to do the sanding and compounding. Make sure the machine has a good shape, is working well, and has a flat pad. 

• Hand block.

It is a small board with a pad on 1 side. It is used to do sanding for some areas where it is difficult to do by the rubbing machine. 

• Buffing machine.

It is a spinning wheel with buff pads. It is used to eliminate the sanding mark from the sanding and compounding. There are some buff pad types needed to do the high gloss rubbing, the white wool, the yellow, and the sponge. 

• Sandpaper

Sandpaper is the material used to sand the finish surface. The wet sanding is the best way to do sanding with high-grade sandpaper. We need the waterproof sandpaper with grades # 1000 and # 1500. 

• Scotch brite.

Scotch brite is needed to do the compounding. There are some types of scotch brite that might be able to be used, but normally we use the white scotch brite (the t-type scotch brite). 

 the white scotch brite for rubbing

• Rubbing compound.

Rubbing compound is material to remove the sanding marks from the wet sanding. There are some rubbing compounds that can be used. The waterbed compound is the most used because it is quite inexpensive and easy in the application.

•  Polishing compound.

It is similar to rubbing compound, but with a finer grade.

• compressed air.

To run the rubbing machine, we need the compressed air. The pressure needed is 6 bars, with consumption of about 600-800 liters/minute. The buffing machine is available in air-powered or electrical-powered. If the air powered is used, then it also needs the compressed air with the volume and pressure being about the same with the rubbing machine. 

• Rubbing lubricant.

It is the liquid that is used to help the wet sanding. This fluid serves to absorb heat that arises in the sanding process. There are some paint suppliers that provide the rubbing oil or rubbing lubricant that can be used. But if we can't find it, we can simply use the mix of water and soap. Use water and add some liquid soap or sampoo in the water, and it works well as rubbing lubricant.

• Rag.

The rag is needed to clean and wipe the liquid at every process of rubbing. The rag should be soft and absorb liquid well. 

The step-by-step of rubbing process to achieve a high gloss finish

• Wet sanding.

It is the first process that is a critical step to the process of rubbing. The objective of this process is to provide a flat, level, and even finished surface. Sanding by hand will require a lot of energy, time, and risk for inconsistency; then the rubbing machine is needed. Wet the surface with rubbing lubricant. Put the # 1000 grade sandpaper at the sanding machine pad, and then run the machine rubbing on the wet surface. Make sure that the surface finish is always wet when the sanding machine is applied. The dry surface will raise the heat and make the sandpaper stacked with coating. It will lead to the deep scratching or sand mark To see how to do the wet sanding, we can see the video attached.

 wet sanding

After some cycles of the machine movement, wipe and dry the surface, and check the sanding result. Make sure we got the flat and even surface. The wet sanding should remove the orange peel, dirt, pores, and grain. See the video here:

 cleaning and checking the wet sanding result

We may have to repeat the wet sanding step if the perfect surface has not been achieved yet. We can use a hand block to sand some areas that are difficult to be cleaned with a rubbing machine. 

 hand block sanding

After most of the pores are cleaned and no orange peel is left, then we can continue the sanding with the finer sandpaper. Put the #1500 sandpaper at the machine and repeat the wet sanding as the first wet sanding.
Clean and check the sanding result; make sure we got the smooth, even, and smooth surface. In this step we need a perfectly smooth, even, flat, and clean surface. Make sure there is no orange peel, dirt, hole, pores, grain, or deep scratches.

• Compounding.

It is the compound application to remove sanding marks from the wet sanding. The compounding process is done with a rubbing machine and white scotch brite as the pad. Remove the sandpaper from the rubbing machine pad and replace with the scotch brite. Mix the compound with water and pour it on the finish surface, and then run the machine rubbing on the surface. Run the machine for a few minutes; keep the surface wet during the compounding process. 

 compounding

Stop the machine and then dry the surface and check the surface. This step will reduce the sanding mark and bring the luster for the finish. This step will produce a flat surface and a smooth and flat surface with a soft and attractive appearance. The gloss resulting at this step ranges from 70 sheen to 90 sheen, depending on how long we run the machine and the type of scotch brite used. However, this step will leave vogue lines from scotch brite. If we want a finish with a clean, no sanding mark, then we need the polishing process.

• Polishing.

It is the process to eliminate the sanding mark from the scotch brite or sandpaper from the previous process. Attach the white wool pad at the buffing machine. Mix the polishing compound with water, and run the buff wheel to polish the surface. Run the buffing machine until the finished surface is clean and dry.

polishing with white wool pad

If we do this step properly, then we will get a high-gloss finish surface. The scotch brite or sandpaper mark will no longer exist, but there will be some thin swirl marks left from the buff wool.
To eliminate the swirl marks, then we need to repeat the buffing but with a softer pad. Take off the white pad, then replace it with the yellow pad. Then repeat the buffing process as the first buffing process

polishing with yellow wool pad

 polishing with sponge pad

Check the finish results obtained; when we did the whole process correctly, then we will get a high gloss surface with a clean, flat, and perfect surface. The sheen resulted is very high; about 95 to 100 sheen.

 the high gloss finish panel