Shapton Glass Stones and swirl marks after lapping, am I doing something wrong?

I am just trying to get a set of stones in shape so I can learn to hone with them. After going through nearly all of them I noticed light scratches in one, so I re-did the pencil grid and lapped on the GDLP again. Now what I have noticed is that once the stones dry I can see the lapping pattern in parts of the stone, as if there is something stuck on the GDLP or I am just seeing the lapping pattern... but only in spots. Its like there is a tiny grain on the DGLP causing the marks in spots.

I can only see these scratches after the stone is dry and held up to light at the right angle. They seem like they are larger than the grit should allow.

And I don't have anything to compare with, now. How can I tell if these swirls are OK, if the GDLP has some flaws in it? or something is stuck on it that does not seem to get removed when cleaned.
I can see scratch marks in the 1k,4k,16k and have not checked all other stones yet.

Could the GDLP be flawed? (I got it used) Or am I doing something wrong?

I am lapping with a good splash of water, figure 8 motion with light pressure and lapping until a pencil grid is removed, the first few stones seemed to all be high in the middle and it would take a while for the edges to hone flat. But now that they are dry I am seeing these scuff marks,, but not sure if its normal. As they can be very hard to see, light has to be just right.

Idea's?

- E

Lap under running water JMO

This comes and goes but can be prevented for the most part with post use cleaning. As long as you are lapping with running water and cleaning off your stones after use (I use Barkeeper's friend and a 3M scotchpad and water, of course) I would not worry about it. Remember how nasty looking some strops can get but still produce awesome results.

I have a set of Shapton GS stones (1K-30K) and lap them with a GDLP. I have noticed some marking on some of the hones after lapping that could be described as swirling, but they haven't affected performance of the hones as far as I can tell. As has been pointed out already, I always lap under running water to flush out any loose particles between the lapping plate and the hone.

If it is inconvenient to lap under runing water, at least thoroughly clean the plate (a bristle brush helps) after use, and place the hone on top of the plate while lapping - any small bits then get a chance to fall into the troughs, hopefully.

As long as the marks are below the level of the surface (which they will be) and light, then its probably nothing to worry about - I see them on mine, too. Finishing lapping with long up/down strokes rather than figure of eights or circles reduces the impact of the lines even further.

If you really want them to be spotless, rub the hones together as a final measure, but make sure you really clean the surfaces down.

Regards,
Neil

I was cleaning the GDLP after lapping every stone. Looking at the swirl marks it seems like there was/is a bit of grit stuck in a few very specific spots. Or a sharp point on the plate, as the scratch pattern is a whole bunch of figure 8's centered in one spot.
Which you would get if there was a bump on the plate that did not move, alot of the stone is flat and swirl free but the same location in other stones has the figure 8 swirl.

I took a dry stone and put it on the Dry DGLP and shifted it side to side by a few MM, And I could see what looked like the "spot" that may have something stuck or sticking out in a few points. I cannot feel it but it leaves a mark on the stone and I can see some residue from the stone on the GDLP.

Is it possible something is stuck in the DGLP causing this? If it was just lack of water or general swirl marks that were consistent over the entire stone I wouldn't question it so much. But the swirl marks are centered in an area and are consistent with there being debris fixed to the DGLP.

You might also check the edges of the GDLP. I have a large dmt325 that had a bur on the edge of the steel plate that made contact with the stones, a quick touch-up with a file fixed it. I still see small swirls like you are talking about when I lap my Shapton's, which is not very often as they don't need it often.

The DGLP is 325 grit, so a bit of marks would be natural.
As shooter says, check the edges on it, and if they are fine, I would say you are seeing what is a natural pattern of 325 grit scuff marks.

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Originally Posted by Charon

I was cleaning the GDLP after lapping every stone. Looking at the swirl marks it seems like there was/is a bit of grit stuck in a few very specific spots. Or a sharp point on the plate, as the scratch pattern is a whole bunch of figure 8's centered in one spot.
Which you would get if there was a bump on the plate that did not move, alot of the stone is flat and swirl free but the same location in other stones has the figure 8 swirl.

I took a dry stone and put it on the Dry DGLP and shifted it side to side by a few MM, And I could see what looked like the "spot" that may have something stuck or sticking out in a few points. I cannot feel it but it leaves a mark on the stone and I can see some residue from the stone on the GDLP.

Is it possible something is stuck in the DGLP causing this? If it was just lack of water or general swirl marks that were consistent over the entire stone I wouldn't question it so much. But the swirl marks are centered in an area and are consistent with there being debris fixed to the DGLP.

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High spots on the plate will scratch like this.

I use them on a regular basis. I don't use the DGLP, I use a DMT and haven't had any problems. I would check the DGLP.