I have just polished a piece of synthetic corundum with Gearloose's new Matrix lap. When I read about this lap I was keen to try it because I've never had any success using the traditional ceramic lap . I know I'm no orphan but then I also know facetors who swear by their ceramic lap.
Gearloose ( Jon Rolfe) describes the Matrix lap as being a "microporous ceramic composite" lap.
I was surprised when I first looked at the Matrix lap because it had quite a rough surface , unlike the hard surface of the traditional ceramic lap. My first step was to smear some light oil on the lap and some 60,000 diamond mixture and dress the lap with a piece of corundum boule with the lap running at fairly slow speed. I did this for about 5 minutes.
Following Jon's advice I then washed the lap with warm water, Morning Fresh and a new stiff nail brush and rinsed it well and dried it.
I then tried to polish some facets on a piece of synthetic corundum that had previously been pre-polished. The results were not good - under the 10x loupe there were many small scratches. I also noticed that on the edge of the facets was a small of residue of white powder which I think came from the lap.
I then applied more oil to the lap and some 60,000 diamond powder and repeated the use of the corundum boule, again for about 5 minutes, and then repeated the washing of the lap.
I went back to the faceted stone and repeated the pre-polish with 3000 Battstick on a Battlap.
I then applied some Diastix 60,000 to the Matrix lap . I found it was difficult to get a decent spread of the Diastix so I added a few drops of light oil and spread the diamond evenly with my finger. I wiped the lap gently with a tissue and tried again to polish the corundum.
I got great polished facets in a very short time - the largest facets may have taken 30 seconds , the smaller ones much less. And the facets were nice and flat. It worked better that the BA5T lap that I have used in the past.
So Gearloose has another winner . The Matrix lap polishes corundum quickly and well.
At this stage I haven't tried softer material on the lap nor have I used Oxide polishes. I caution that this is the result on only one stone and will have to be repeated before I could say it will always work.
Like all faceting , it is essential to get a good pre-polish. I have two pre-polish laps , both Battlaps , one with 3000 diamond and the other with 8,000.
And like most new laps the Matrix requires some preparation. In my case I used light oil and plenty of 60,000 diamond with a corundum boule. Other facetors may find other methods works equally well or better.
So if you want a lap to polish hard stones like corundum I can report that the Matrix has been excellent.
I'm sure that as more facetors try this lap there will be more tips and hints about the usefulness of this lap.
P.S. I got my toughest critic (my wife) to look at the polished facets under our Gemmological microscope ( 40x) and she agreed they were good.
It's a warm fuzzy feeling when something new works so well.
PPS I use the nickname "Scratchie" because it has taken me years to learn how to avoid scratches !!
John
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