Official Luthiers Forum!

Ok so here's the update on my experience with KTM-9, I sprayed the Koa guitar and only did about 8 coats and let it cure as an experiment. Took some good 3M 800 gold paper and sanded it flat with a cork block, then took it to the polishing wheel with medium and then fine Menzerna polish.

It's shiny but it's still got little scratches all over it, with McFaddens I used Meguire's #9 swirl remover and they vanished. But on the KTM it seemed to fog things a little, so is there another step to getting a good high gloss with KTM-9? I orderd some of Stew-Mac's swirl remover and one of their pads to see if that would work.

I might take it back over to the polisher again and see if I can get them out, I will say that other than this the finish looks wonderful, it's deep and clear and looks really nice and warm. I have two more in the closet that are ready for final polishing but I want to figure this one out first before I do them..

Any advice would be greatly appreciated...

Cheers

-Paul-

P.S. I'll post some pictures once the tuners come in...

_________________
-Paul-

Patriot Guitars

I think you're seeing sanding scratches from the 800
grit. You'll need Menzerna coarse compound to get
them out, the medium compound just isn't
aggressive enough. KTM-9 really likes to hold onto
those scratches, and it doesn't burnish at all - you
have to mill every last scratch out.

I've recently started using the Menzerna paste
compounds that Grizzly sells, and they're better than
the hard wax bars. They're a little messy, you just
wipe a blob on the surface and start buffing so the
wheel takes up the compound, so some of it will end
up in your hair, the ceiling, etc. But they're more
agressive and generate less heat.

Here's my latest rub out sequence, which I have not
tried on KTM-9 yet but I think it should work fine:

1) Level with Mirka Q-Silver 600 grit on a random
orbit sander. Get it dead flat, no shiny spots left.

2) Hand sand wet with 1500 grit wet-or-dry, against
the grain. I cut a hard foam sanding block about 2" x
3", cut a piece of sandpaper about 1/4" bigger than
that all around, and stick it to the block with
double-sided tape. Don't crease the paper or you'll
sand ridges into the finish. Use plenty of water and
light-moderate pressure. Wipe off the slurry when it
starts to drag and add more clean water.

3) Buff with coarse Menzerna paste with the grain
until the 1500 grit scratches are all gone.

4) Buff with medium Menzerna paste against the
grain until the coarse compound scratches are all
gone.

5) Buff with fine Menzerna paste with the grain until
the medium compound scratches are all gone.

At each stage, you can best see what you've
accomplished by bouncing the light of a naked light
bulb off the finish. Look across the surface in the
direction of the scratches you're trying to remove.

I usually go with 600 then 1200 and possibly a rub with 2000 before I go to the wheel and it really polishes uo nice.

_________________
Tickle your guitar daily, and it'll tickle you back.

Paul,


I just finished testing the KTM9 against the catalyzed high gloss urethane I usually use on a bunch of different exotic sample boards and here are my results.

I dry sanded both products to 800 grit. I normally wet sand the cat urethane but since the other side of the board was the KTM9 I decided to dry sand both of them.
I used the Menzerna compounds from grizzly and a dedicated buffing wheel for each grit. I started at the 800 grit compound then went to fine and super fine. For the last buffing and to remove the residue from the compounds I put a dab of regular turtles car wax on the sample board and quickly buffed to a high sheen. I know that Doolin sands to higher grits before going to the buffing wheel and I did this on some boards as well. However, I found that 800 grit was sufficient if you use the correct compound to remove the sanding marks.
My results were better than expected from the KTM9. I put the high gloss urethane on one side of the board and KTM9 on the other. Sometimes I really have to look hard to remember which is which. There is one drawback to the KTM9 that I found. I can finish a piece in 4 days with the cat urethane and KTM9 needs at least 7 to 14 days cure time alone.
Hope this helps.

[QUOTE=John How] I usually go with 600 then 1200 and possibly a rub with 2000 before I go to the wheel and it really polishes uo nice.[/QUOTE]

same here except I use Micro-Mesh 6000-12000 instead of wet-dry 600-2000 on my last leveling session. I think I leave a more consistent depth of scratch with Micro-Mesh than with standard wet-dry paper. This makes buffing out the final scratches more uniform and quicker. I use an orbital with 5" Micro-Mesh pads. The micro-Mesh pads are more expensive but last a lot longer and produce less heat. MichaelP38398.5069097222

Ok so I'll try sanding down with a finer paper, need to order some good 1000 and 1500, I don't like wet sanding unless I have too, with the 3M gold papers I don't get clogging at all (it helps to wait 2 weeks for the finish to cure as well), I use a micro-fiber tac rag as I'm proceeding which helps too.

I'll play with it tonight and see what happens..

Thanks all..

-Paul-

_________________
-Paul-

Patriot Guitars

WOOOOOO HOOOOOOO

I took the guitar apart tonight, pulled out some 1500 a good cork sanding block and a little soapy water and went to town. Then loaded up the buffer with some polish and put the spurs to her REAL GOOD!!!

The result is what I was looking for, I think I was being a little too gentle on the finish so this time I let it heat up a bit as I polished, in fact it was sparkling just from the medium compound and I knew at that point I had a winner.

Since I only have one buffer I stick with the medium and fine, Mike do you think that following to extra fine would make a difference??

So I'm now %100 sold on KTM-9 (just ordered a gallon of the stuff), it polished out perfectly and I challenge anyone to tell me it's a water based finish by looking at the results. It looks just as deep and warm as McFaddens and really started to sparkle once I let the buffer heat things up a little. I'm one very happy builder, the epoxy did the trick with the Koa and the finish is really nice and level, if I could I'd give you all a big ol bear hug

Thanks for the advice gang..

-Pauil-Sprockett38399.0639467593

_________________
-Paul-

Patriot Guitars

I only have one buffer too, so I leave the coarse
wheel on the left and switch between the medium
and the fine on the right. The fine paste gets it pretty
darn shiny, but I've also used Finesse-It on a foam
pad on my ROS as a last step, to get out the
directional sheen. I didn't find the Menzerna extra fine
to be very effective.

Ok so I'm in the same ballpark then, I found the coarse to be too rough and medium to be just right for getting the initial shine on the instrument and the finishing it off with the fine. I really hate changing wheels when I'm buffing so my setup is perfect for the lazy like me

I have some Finesse-It on the way here so I can give it a try as well as some of the stew-mac polish, I'll see how they work

I think the real trick for me was too let the finish warm up under the buffer, I don't know if that helps the KTM with hardness but it sure made it more shiny. On shellac it's the only way to get a really good hard finish and some lacquers harden up more when you heat them while polishing, I just don't have enough experience yet with KTM to know for sure.

Thanks for the advice Mike.

-Paul-

_________________
-Paul-

Patriot Guitars

Paul If you want to make the buff out a little less intense try finial prep-sanding with the Micro-Mesh 8000 then 12000 pads on a ROS. You can get the round pads at https://www.micro-surface.com. In fact I find that after the 12000 Micro-Mesh (finer than 2000 wet-dry paper) that I have a nice satin finish prior to any buffing. For high gloss finish I go straight to the med menzerna after final sanding with the Micro-Mesh and skip the coarse all together. This allows me to work with just 2 wheels, one for medium and one for fine. and Like Mike (What a pleasure it is to have him with us on this forum) I polish out the directional glaze with a foam pad on the ROS. But I use the ultra fine Maguire's polishMichaelP38399.4783333333