Hello everyone, I have the following question.
I have a Tormek SJ-250 Japanese water stone (4000 grit) and Tormek - PA70 polishing paste (3000 grit, if I'm not mistaken). Does it make sense to use a coarser polishing paste after using the water stone with 4000 grit?
Not really. However, there are many different grit standards and it depends on the actual grain size. I think you would be better off with a 2 micron or finer honing compound. One solution is to use a metal polishing paste which is usually super fine.
Welcome to the forum, Johann. My thoughts will probably differ from many on the forum. Please note that I am not saying that other thoughts are wrong, just that mine differ.
I think relying entirely on grit size is an oversimplification. Over the years, I have heard several grit numbers for PA-70. I have also noticed that the 360 grit DC diamond wheels cut faster than the 220 grit SG wheels. I have no special training in abrasives; I am just basing this on my observations.
Here is my suggestion to answer your question: Sharpen two chisels around 3/4" width. The two sizes don't have to be identical, as long as they are close. The backs don't even have to be polished for this test. Go through your normal sharpening sequence:
1) SG graded coarse.
2) SG graded fine (do not skip this step)
3) SJ
I suggest using two chisels because the large bevels are very visible. Add using the leather honing wheel with PA-70 to one chisel. Compare the scratch patterns of the two chisels.
Continue with sharpening using the leather honing wheel and PA-70 on half the tools. You will answer your own question.
Keep us posted.
Ken