Expert: Thomas - 3/27/2011

Question
Hello Thomas,
I am a hobbiest wood worker and am teaching myself how to inlay MOP in my work. Recently I bought some pink MOP blanks that came with longitudinal machining grooves in them which I need to remove. What kind of compound will do that and what do you recommend as a polish? I have a Dremmel, a large buffing wheel and various kinds of sand paper. I just don't know anything about the compounds.
Thank you for your help.
Arthur

Answer
Arthur, mother-of-pearl is relatively easy to polish. First you need to remove the deep scratches and in your case, the machining grooves.  Keep in mind that removing a groove or scratch means taking the entire surface down to the level of the bottom of the groove. If this will leave the material too thin, consider sawing away the grooved area if that leaves enough mop for the intended inlay. A jewelers saw blade (perhaps a 1 down to a 1/0 in a coping saw frame will work to saw the mop even if dulling the blade quick quickly ( use water to lube).

Mother-of-pearl dust will irritate if breathed and sanding should be done wet.  While I use lots of wet/dry silicon papers for some wood work the sanding is generally done dry except for special finishing situations. If you have the right grade (grit) wet/dry papers you can start right away to sand down the pearl blanks. If not, consider an auto parts store for sand papers.  Papers for auto body work come in grades finer than the general hardware store variety of wet/dry sandpaper. Also, while at the auto supply store, ask for plastic polishing compound, the kind for the final shine. This is generally a solid wax based compound in a cardboard tube or similar container. The plastic buffing compound will put a wonderful shine on mop. A jewelery polish which works well is called Fabulustre©, a white compound. You do not want to get these compounds in the grain of wood since the color might be hard to get out.

You might want to use the Dremel™ for sanding but will kick up dust and it is easy with small wheels or sanding rolls to leave ripples in the surface.  Start by wrapping sandpaper on a flat stick and working it wet by hand on the mop. To remove a lot of material quickly, use 220 grit, not that coarse but it cuts the pearl fairly quickly. If not quick enough, go with a 100 grit but try not to go coarser than that because you have to take out the sanding marks  step by step to get to the finish.

Progress through 600 grit, skipping a grade if it works for you. Try the plastic polish on a rounded felt buff or even a slightly firm cotton buff.  Wipe off and check out the shine. If more sanding is needed, step back to the grit you skipped then go on. Generally, a 600 sanded finish will polish quite well. If for some reason it shines but shows sanding lines, go over with 1000 grit, wet and gently. Rinse and dry the mop and look at the surface as you turn it at angles in the light to see the entire surface clearly. Does all look uniform and the same gentle frosted (somewhat shiny) surface?  Correct any sanding lines you see.  

When using the plastic polishing compound, this is generally used dry and is not cutting the pearl. The surface is being brought together for a shine but is not being sanded. Do not run the Dremel™ polishing wheel at full speed but rather start sort of slow and see the results. Add compound as needed. You will pick up a feel for speed and pressure to use to get the shine working up quickly. Keep the buff moving around on the entire piece as you go.

Arthur, there you are! : )  Now all you have to do is fit the inlay and see the results of your labor.

With wood working and some experience with the Dremel™ rotary tool, I believe you can sand and polish the mother-of-pearl with wonderful success. Once you work one piece it will be easier from then on. There are not really any surprises to watch out for with this material. Just keep it wet and keep the dust down; polish gently and do not let the material get very hot while polishing.

If you need to ask more on this subject, feel free to use a follow-up question. Oh, if you get a chance and want to do it, please rate the answer so I will know how well I am doing out there. Fair enough?


God Bless and Peace.  Thomas.