Official Luthiers Forum!

What is your approach in flat sanding lacquer considering CAMI and FEPA grits during the process?
I have been starting with P1200 which is equivalent to 3M's 600 CAMI grit.
I have amassed a great selection of both grades (Kovax, Mirka, 3M ect), but using both in the same sanding schedule (converting/ equivalence/ best practice) is starting to concern me in respect to the "quality" and thickness of the final finish, in regard to the sandpaper I used (US or P graded). P1200 is equivalent to US 600 grit, and I am questioning what to even start with now.



Many of these grading systems charts are available, are they all correct?
https://abrasives-south.com/wp-content/ ... 8x1324.jpg
https://www.abrasiveresource.com/v/vspf ... arison.pdf

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Measure Twice,

Karl Borum

Micron size.
You should be able to find a chart listing micron size for the various systems.
I have one I printed out many years ago. I can intermingle systems that way.
I find it helpful.

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Jim Watts
http://jameswattsguitars.com

Just within the last month I finally got all of my sandpaper changed out so I'm only using P grade. I got tired of using the chart to see what was what. All told it probably cost me about $200 since I only use the good stuff. I think it was worth it.

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Steve Smith
"Music is what feelings sound like"

I'm with you Steve. I stay with P grade for finishing and Cami/micron for sharpening on my 1" x 42" belt sander and Veritas powered sharpener. Less confusion for me for sure.

For sanding finish materials I like to use micron discs. The "grit" is on a Mylar backing and is of a uniform size so the sanding scratches are more uniformly sized. You can wash and dry the discs so they last longer than regular sandpaper. For finer sanding the Trizact discs work well, also on Mylar and fairly long lasting.
For sanding wood I still use Cami and P grade papers.

when you get info finishing this is a whole new ball game. Look up asilex paper you won't turn back this stuff is amazing

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

What is a good schedule for lacquer using the micron scale ?

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Measure Twice,

Karl Borum

I like to go 60 micron (remove orange peel),30 micron (flatten), 15 micron , green trizact, blue trizact, (remove scratches) then buffing compounds (polish).

Micron chart:
https://support.wickededgeusa.com/porta ... sion-chart

Being uniformly sized particles, when the micron scratches start disappearing the rest quickly follow, and then it's time to move to the next size down.

Are these micro grades always used dry?

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Measure Twice,

Karl Borum

I like to use them wet with an orbital sander set at a slower speed for the flat surfaces, and by hand (or with a hand held block) for the last centimeter near the edges. Trying to sand up to the edge with a powered sander usually leads to burn throughs for me. A small amount of detergent in the water seems to help. The discs are on Mylar film and hold together even when wet and can be washed and dried for reuse several times.
Trizact is used wet also and behaves similarly.

Thanks for replies, its new territory for me. I have multiple different books, LMI's verbose Lacquering instruction and JJ's finishing class on-line, and they all use traditional wet sanding paper and schedules. Bet this is going to cost me $$$

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Measure Twice,

Karl Borum

If you go to an auto parts store that sells auto paint you may find 5" micron and trizact discs you can buy by the piece. You probably only need one each to finish a guitar (possibly a couple of guitars).

I'll give the auto paint and supply store a whirl. I used to go there to buy Wet or Dry by the sheet.....almost forgot!

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Measure Twice,

Karl Borum

Would the 3m Brand of micro graded paperbe appropriate (lacquer flattening/ finishing)?
Assilex/ Tolex are confusing to me.

Excerpt:
The superior flexibility of the non-woven, tear-resistant synthetic backing on this Polishing Paper allows for fast and easy finishing and polishing of numerous materials, even on highly contoured surfaces. They are excellent for finishing jewelry and precious metals. They will remove scratches and restores transparency to acrylic and polycarbonate windows on buses, aircraft and trains. They are ideal for plastic, polyurethanes, fiberglass, solid surface composites and wood. Their precision micron grading provides a uniform, consistent finish which shortens hand-sanding and buffing time, reduces finishing steps and saves time. They can be easily cut into strips. They can be used wet or dry. These sheets will not load or clog easily, and can be washed with soap and water. Polishing paper available with micron graded silicon carbide or aluminum oxide minerals. Sheets are color-coded for easy identification.

Set includes the following grades:

30 micron (600 grit) Silicon Carbide, Army Green
15 micron (1200 grit) Silicon Carbide, Grey
9 micron (1800 grit) Aluminum Oxide, Sky Blue
3 micron (8000 grit) Aluminum Oxide, Pink
2 micron (10,000 grit) Aluminum Oxide, Aqua Blue
1 micron (14,000 grit) Aluminum Oxide, Ivory.
All sheets are Non PSA (Pressure Sensitive Adhesive). All sheets are 8-1/2" x 11".

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Measure Twice,

Karl Borum

The 3M brand materials I have worked with have always been first rate, if a little bit more expensive than some other brands. With the small quantities most of us would use over the course of a year it probably doesn't matter. I haven't used the finest grades mentioned (usually go to polishing compounds) but I would be interested in how they might work out.