Official Luthiers Forum!

I just received a great supply of MOP from DePaul supply and am going to start working on a rosette. Can somebody tell me a good way to trim the ends? Also, what type of glue would you use for inlaying MOP in a rosette, and how do you cover up the cracks? Can you use MOP dust to fill cracks?

How do you shine MOP? Do you treat it just like your finish and sand/polish, etc? Any other pointers working with MOP would be greatly appreciated.

Thanks!

John

John, I don't have a ton of experience with MOP except for my logos on the headstocks. But I'll give you what I can. I would fit the MOP to the cavity and when satisfied, float in thin CA. That's what I've done and it's worked very well. I'm not sure I would try to hide a crack. It doesn't seam like you'll have much luck, though I could be wrong. I've found that if you don't try to clean it up it just looks like a vane and appears natural. Yes on treating it like finish. Just sand flush and finish/sand as you would wood.
Other pointers. DON"T BREATHE THE DUST. It will kill you. Have a respirator on while cutting and sanding it.
That's about all I know about it. You might email Craig Lavin, I really knows his shell

Seal the surrounding area with shelac before beginning or the CA could discolor your top. I use LMI white glue and or CA for my rosette work. Leave your pearl just a shade high then run it through the thickness sander to level everything.

_________________
tim...
http://www.mcknightguitars.com

You can't "trim" mother of pearl, or any pearl. It's either cut, file, or if it's abalam, some people work it with dremmels and cutters, and sand the edges smooth. As far as joints between pearl go, there is very little to do to hide them. They are either tight, engraved into the pattern, or you have to design the piece with the joints in mind.
Pearl dust is not going to do anything for you. differing pieces of pearl frm different orientations are goign to refract diffeently as well, so unless you plan out carefully the complete pattern it will flash oddly. Some pieces may look dead, while others are bright.

You need to start your rosette as any inlay- design it out on paper, then cut it out with a jewelers saw, file-fit the ends, and if your dopping it into a pre-made route, just drop it in, and fill with thin liquidy CA. Let it dry overnight, sand level starting at 80, then 120, go to 220, end with 320, finish. NO need to go higher than 320 with a finish over it.
Fire away if you need to .
Craig

_________________
www.handcraftinlay.com

I don't seem to be able to let this go, despite way too much bad
experience. The misinformation keeps coming up and I always jump on it.
Never learn. So here I go, once more:

Pearl dust isn't poison.

It's better not to inhale it (true of virtually any solid, I think), but it's not
poison. According to OSHA, it's a "nuisance dust," not as toxic as wood
dust. People working in clouds of dust -- the people who grind the shells
into flat blanks without benefit of dust collection or any sort of mask --
sometimes have what I understand to be an allergic reaction. That's bad.
Don't get a job in any of those SE Asian sweatshops. Other full-time
grinders report more frequent sinus infections and other minor irritation-
linked problems.

Note: Full-time. These people are immersed in dust every day, for many
hours! All the readers of this forum together couldn't create that much
dust with our little jewelers' saws and 4/0 blades!

Most of the professional cutters -- Larry Robinson, David Nichols, et al --
I don't know about you, Craig -- don't wear a mask since then they can't
blow dust off the cutting line. I often use a regular nuisance-dust mask
when I'm cutting a fair amount of pearl at one time, and I have a tiny
pump that blows the line clear for me. But I wear the mask for comfort
more than for any documented health hazard.

Like a lot of woodshop practices, you have to make your own choices
about the level of safety you need (my safety fetish is the tablesaw; I think
mine covets my fingers). But be accurate about your personal risk
assessments.

John,

I assume you are using the curved MOP strips that DePaul sells specifically for rosettes, so they are already an appropriate radius, and all you need to worry about is making the joints purdy where the pieces meet.

Its as simple as this:

First, make sure the channel has been coated with shellac.

Second, Choose your first strip and place it in the rosette channel. Take your second strip and put it next to the first one in the channel, and guestimate how much you have to file off the inside/outside corner of the first piece to make it match the first piece for a clean joint. Then just remove the second piece from the channel, take an ordinary file, and file the edge of the second piece until it fits nicely against the first piece. Continue with the subsequent pieces. I don't worry about the joint at the top of the rosette because it goes under the fretboard. I'm slow, and the whole process takes me maybe an hour.

Third, with all of them in there snugly, superglue them in. When the glue dries, run it through the thickness sander until everything's flush. (Your shell material should have been a hair thicker than the depth of the rosette channel.)

Sand and laquer as you do with the rest of the top.

Hi Rick.
I use a shop vac to constantly pull the dust away from me during cutting. It keeps the lines perfectly free of any buildup. This is how Larry R does it as well. Larry doesn't wear a mask, but he also states that he doesn't see any pearl dust rising up in his halide lamps, due to his strong shop vac which leads outdoors, so he feels safe not wearing one. Grit I believe does not wear a mask during cutting, as of course very small pieces can get sucked in. Larry just re-cuts anything sucked in. You can of course put a screen in front of the thing, but whatever..
I do wear a mask as well as use my 5HP shop vac. I really rather not, but I dive frequently for photography, so I rather not risk anything that might effect my ability to do that.
Craig L

_________________
www.handcraftinlay.com

nuisance dust?? Like asbestos shell dust will cut the lining of the lung and cause silicosis. Of course a well designed dust collection will eliminate this problem. However if you don't have a good dust collection system for cutting pearl or any shell you are putting your self at risk. Just as you do if you work wood with out protection. If you don't have a collection system that pulls the dust away be smart wear a mask.MichaelP38421.3918402778

Michael -- are you saying that shell dust is asbestos?

I use to have the same strong feelings about inhaling the dust as some of you. In fact, I routinely contributed to forum threads like this one - many a time I've recited the silicosis connection.

But, I relaxed my views a little after an M.D. on another forum responded to my silicosis dissertation. He explained, in a convincing way, that silicosis cannot be attributed to inhaling shell dust. I wish I recalled the details so I could disseminate them now.

I think one contributing factor leading to the inflation of the shell dust problem is that in the past (the good ol' days??) some aquatic creatures including shells (directly or indirectly) were harvested after first releasing a cyanide agent into the water, to stun the faster species and to release the huge foot of the abalone. Of course, inhaling cyanide tainted dust would probably be a concern for everyone. But, supposedly, that practice isn't performed any more.

Nowadays, I've evolved to view more like that of Rick. That sort of approach, probably seeming lax to some, is likely fine for luthiers doing an occasional inlay. Continuous exposure, day in and day out, is another matter because of the cumulative build-up of dust in the lungs. I feel it's best not to inhale any kind of foreign material, and so for shell I prefer to prevent that with either a mask, or collecting dust before it reaches your lungs using a vacuum. A piece of pantyhose over the inlet of a shopvac goes a long way in rescuing small inlays that occasionally get sucked into the bowels of your shopvac.

Plus, then you have most of the pantyhose left over for other fun things!
;-)

Pete

Sorry guys, I didn't mean to start this big safty first thread. I wasn't implying that MOP dust is toxic (though any foreign material entered into the lungs is basically toxic) I was just stating that it is very unhealthy to breathe. As is spruce dust, as is lawn mowing dust...
Rick it would be rude of me to call you foolish but if you think that not taking any safety measures is fine, well, that's just foolish. Sure there are people in third world countries breathing it all day every day. But I would like to see studies on those people's breathing in about 20 years.
What I was trying to say to John is just be safe. A vacuum is great, a respirator is great, but going completely unprotected is not so great.

Paul,

I'm not at all sorry that you started the thread! It's a topic that surfaces
from time to time, and I think it's valuable to us all to visit safety issues
often. As I said, everyone has to make their own choices about safety.

I will be defensive enough to point out that I agreed with you to some
extent -- that inhaling any solid is not good, that a dust mask is
appropriate (though it has drawbacks regarding convenience and
accuracy). I never said that "not taking any safety measures is fine". I
know that I'm foolish in many ways but I don't think this is a good
example.

My point is just that shell dust is not poisonous -- and there's no report
in the scientific literature of it killing anyone. It's an irritant and can cause
problems if exposure is great enough or if you're particularly susceptible.
But it isn't asbestos and it doesn't contain toxins in an available form or
at a measurable level. Use the level of protection you think appropriate
given the actual evidence, that's all I'm saying.

I have to admit, this is good news to me -- I'm one of those crazy over board worry warts. I get worried when I send a top through my thickness sander to level a rosette and its connected to my dust collector for crying out loud!

Great Thread guys!

_________________
Support the OLF! Bookmark our STEWMAC link Today!
Lance@LuthiersForum.com

[QUOTE=Rick Davis] Michael -- are you saying that shell dust is asbestos?[/QUOTE] I have answered twice but for some reason the server don't like me No... I was saying that shell dust cuts the lining of the lungs like the fibers of asbestos does. My opinion that it is important to know the risks and precautions need to work safely with shell. I adore working with this material. I don’t have down draft dust collection, I use a shop vac and a small compressor to blow dust off the cut line, and I wear a mask. I agree that shell dust is not a toxic agent, nor is it a known cancer causing agent. However it does offer real health issues that need to be addressed if you intend to work with it.

John
To shead a little more light on one of your first questions, I square up the ends of those pearl strips, whether they are curved or otherwise, using regular wire cutters that have had the face gound off so that the cutting edge is flush with the face. (I did that on the belt sander) The pearl just snips off cleanly with a very flat cut. Its easy and quick and I get a cleaner joint that I do trying to file the ends square.

John

I like that idea JK. I use my bench grinder, just install one piece then grind on the other end until it mates up. I've done all of two rosettes so far. And they look good even the Mop one. But I like simple. Any particular brand on those dikes?

Great idea John. Thanks!

_________________
Dave Rector
Rector Guitars

Sears Dikes I think. Nothing special. But by grinding the outside curved surface to the point where that edge breaks on the outside of the cutters, and by polishing that surface to reflective smoothness, you can see how square the end cut is.

Its surprising how cleanly the pearl cuts.

I use a fine back saw (either a "blitz" or an exacto brand) to cut the ends of the strips for the rosettes.
I made a little jig (actually a "mitre box") that the curved section of abalone fits in with a slot for the saw to cut the pieces ends square. I'm pretty sure this is from C and N's book-Has always worrked great for me.Brad Goodman38422.2964699074