" " wisno wood furniture finishing: Rubbing and polishing for high gloss finish.

Saturday, November 17, 2012

Rubbing and polishing for high gloss finish.

The rubbing process is the other method to make the high gloss finish instead of using the full gloss top coat. This rubbing process is process to finish the finishing layer to make the perfectly flat and smooth surface. We already posted article about the information about the rubbing process at 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 form the finishing layer. The finishing layer surface need to be even and flat. The finishing is also need 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 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 lbs double pad sanding machine. It is needed to do the sanding and compounding.  Make sure the machine has a good shape, working well and has a flat pad
  • Hand block.
It is small board with a pad at 1 side. It is used to do sanding for some area where is difficult to be done by the rubbing machine.  


  • Buffing machine.
It is spinning wheel with buff pads. It is used to eliminate the sanding mark from the sanding and compounding. There are some buff pad type 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 grade # 1000 and # 1500. 
  • Scotch brite.
Scotch brite is needed to do the compounding. There are some type of scotch brite that might be able to be  used, but normally we used 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 compound can be used. The waterbed compound is the most used, because it is quite inexpensive and easy in the application.
  •  Polishing compound.
It is work similar with rubbing compound, but with finer grade.
  • compressed air.
To run the rubbing machine we need the compressed air. The pressure needed is 6 bars with consumption is about 600-800 liter/minute. The buffing machine is available in air powered or electrical powered. If the air powered is used, then it also need  the compressed air with the volume and pressure is 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 is arisen in the sanding process. The rubbing lubricant usually is available at the finishing sore.  But if we can,t find it, we can simply use the mix of water and soap.

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

The step by step of rubbing process to for high gloss finish
  • Wet sanding.
It is the first process that is critical at the process of rubbing. The objective of this process is to provide the flat, level and even finish surface. Sanding by hand will require lot of energy, time and risk for inconsistency; then the rubbing machine is needed. Wet the surface with the 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 on. The dry surface will raise the heat and make the sandpaper is stacked with coating.  It will lead to the deep scratching or sand mark To see how to do the we sanding we can see the video attached.


 wet sanding

After some cycles sop the machine, wipe and dry 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 prefect surface has not achieved yet.  We can use hand block to sand some areas that are difficult to be cleaned with 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 with 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 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 rubbing machine white scotch brite as the pad.  Remove the sandpaper from the rubbing machine pad 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 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 lustrous for the finish.  This step will produce a flat surface and a smooth and flat surface with soft and attractive appearance. The gloss resulting at this step ranging 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 form the scotch brite or sandpaper from the previous process.Attache 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 finish surface 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 is left from the buff wool.
To eliminate the swirl marks, then we need to repeat the buffing but with softer pad. Take off the white pad then replace 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

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