Official Luthiers Forum!

Hi All,
I've really enjoyed some of the recent threads, especially on wood prep and finishing. Didn't want to hijak, so here goes my question. A few folks here mentioned a brand of sandpaper (a 3M product, I think) that they used DRY for final sanding before buffing. It was a no-load paper, and they benefit they talked about was the lack of wet-sand slurry. Was wondering if anyone could comment on that final 320 or 400 up to 1200 or 2000 sanding just before the buff wheel? I'm slowly ascending the learning curve with a fuji mite-4 and KTM9, and have one curing right now waiting final finish. Any advice would be appreciated. (this was the one i sanded through MUCH quicker than I thought possible, so back to the spray booth it was!)

thanks,
Dave F

If you are using a buffing wheel or an arbor there is no sense in sanding out to 2000 or even 1200. You can start with Menzerna P204 after 600 grit sanding, or if you use 113GZ pre-polish you only need to sand out at 400, that's what I do. It's also what the large manufacturers do.The whole level sanding process is basically one step done dry with a typical no load paper. Buffing goes much quicker than sanding.

Here is a link to Menzerna's info on polishing painted surfaces.
http://www.menzerna.com/fileadmin/user_ ... hure_E.pdf

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I think this is the stuff you're looking for: http://www.stewmac.com/Luthier_Tools/To ... paper.html

I've used it on waterborne finishes and it works really well. Get a brush or something to dust it off with and it will work even better. You'll have to brush it often but if you do so, you can get good results.

_________________
http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

+1 for 3M Gold Fre-cut. It lasts a long time, and I believe it's non-stearated so contamination between coats of waterborne isn't a problem. Have you tried EM-6000? I tried the KTM9 and found is much harder to work with.

Cheers, M

Brian, are you saying you only sand out to 400 and then use the wheel with the pre-polish and intensive polish? How long do you spend buffing each paste?

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

I'd like to know too, Brian.

And how many different buffs do you have?

Thanks all. I thought it was the fre-cut, but not sure.
No, I haven't tried EM6000. Just finishing my first water-based ever, with KTM, but will give it a try. Guess I'll have to build another guitar. ;-0

Lots of variable to sort through learning a new finish system. Air flow, pattern, proper thinning, rate of sweeps....all affect what you lay down. I'm just starting to figure out what's what, and what I'm doing right, and what I'm doing wrong. (so far the latter is leading the former)

When I finish the KTM, maybe I'll try the EM6k.

Thanks again, all comments were helpful and give me something to think about.

Yes, I level sand at 400. I sand to remove 90% of the surface texture, the rest will come out in the buffing. I run 4 sets of buffs & compounds. Menzerna compounds 113GZ, P204, GW16 & Atol6 in that order. I spend the most time with the first compound and each successive compound goes quicker than the one before. I always keep the previous buff on the other side of my arbor so if I see something that I missed I can skip back a compound and catch it without any fuss. The average guitar takes me about 2.5 hours to level sand and buff.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Brian, I find that amazing!
I have struggled for years trying to figure out the right combo for sanding and buffing EM6000 to get a scratch-free finish.
Currently I block sand dry with P800 Fre-Cut Gold, (takes hours) then wet sand with with wet and dry using mineral oil - 1000 - 1500 - 2000, then hit it with micromesh and oil - 3200 - 4000 - 6000, then have at it with the buffer.
I start with the P204.
Looks great, but takes all bloody day.
Looks like I am going to have to get me some 113GZ.....

I have to agree Brian. I have been dry sanding to 800 and wet sanding to 2000 then using the 113GZ and next the GW16. Always looked at first like I was going backwards and now I guess I find out I was. Ends up Ok but Looks like I am going to try to adjust my schedule.

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

Dang it. Now I know I'm going to have to get a buffer - just have to figure out how to shoe-horn it into my shop.

_________________
Steve Smith
"Music is what feelings sound like"

Funny how when friends or other parents stop by and want to see the shop, they pay no attention to the nice chisels, pre-war stanley planes, drum sanders.....and pop their eyes out at the BUFFER!? Apparently, that is what solidifies that I am some kind of expert in the minds of "civilians".

Thanks for all the great comments. I'm going to stop dry sanding at 400 and double check my buffing compounds again.

It'd be great to hear how it goes with the new technique.. Don't forget to stay focused and maintain a death grip on that guitar when running that buffer!

Best, M

Be advised... P-grade paper is in reality courser than what you expect. That is, P800 is 400 grit in ANSI. This has got me in trouble before. With P800 you can easily sand through your finish. Check out this conversion chart.

http://www.fine-tools.com/G10019.htm

_________________
Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Brian,

What size wheels do you run, and how thick are they?

Good question and are you using P or ANSI grit paper?

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

P 400 paper, Menzerna is a european co. and that is the european grading system.

I run 14" buffs, two 1" wide side by side for most things but strip down to single buffs for tight cutaways etc.

As to the hold on with a "deathgrip", I found wearing a set of modern work gloves provides a firm hold with less grip pressure.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

I also wear Atlas gloves when buffing. Nice and grippy!

Brian, thanks for clearing that up.

Steve,
I am glad you brought this up. Until I discovered a similar chart a few years back, I was skipping back and forth between the P and the ANSI and did not understand what was happening. I might sand to 600 ANSI, and then go to a sheet of P800, thinking I was progressing, when actually it was like dropping back to 400 ANSI. I drove me crazy until someone pointed out the difference. It gets worse as the grits get finer. 800 ANSI is the same as P2000.

I am amazed that there is not more emphasis, as to the type grit, when a grit is referred to in literature or websites. Most of them just seem to assume you know which grit they are referencing.

And then you have to add Micro-mesh and others to the confusion: P800 is the same as ANSI 400, F360, J700, and MM1500. I think my brain just exploded.

Sorry, I did not intend to hijack. Carry on

James

Yes, I find it very confusing because almost no one tells us what system they are referring to when they discuss grades of sandpaper. I just checked my shop and everything out there is listed as P grades, so I have been sanding with coarser grades than intended. Also, if P grades are European, why is all my USA sandpaper listed in P grades?
Mike

Started out that way I guess now it crosses over. FWIW, I use P grade because it is more uniform in particle size and to me seems to give a better i.e. smoother surface.

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

It's kinda like metric and SAE. Be aware and know how to convert - good thread. Print out the chart and post it in your shop.

_________________
Steve Smith
"Music is what feelings sound like"

Brian, do you use the same buffing schedule for nitro, as waterborne, as poly?

Thanks, Michael

For the most part yes. I run 4 different finishes out of my shop, French polish, nitro, epoxy urethane & conversion varnish. The FP is the only one that does not follow this buffing schedule. I do not do any waterborne but if i did it would follow this schedule. The differences in how the different coatings are run through the process comes in the buffing process. The softer coatings like fresh nitro will often need buffed harder than a harder coating like conversion varnish. A harder coating is easier to buff through than a softer one.

A common mistake most make with a buffing arbor is not using the compound correctly. Most will apply to much compound at a time and do so to infrequently. Aside from the 113GZ you should not see a lot of compound build up on your wheel. If you are running the wheel on the bar of compound for more than 10 seconds to load it you are overloading it and wasting compound as well as adversely affecting quality of the cut. Buffing to long between applications will also greatly degrade quality of the work. You want the compound to do the work, not the cotton of the wheel itself.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

So I tried this on my last guitar and "lo and behold" - an amazingly shiny finish. Not that I didn't trust you Brian but it sure did amaze me. AND it was so much easier than what I have been doing. Thanks for the advice.

_________________
"I've been had again"
Tim Benware
Creedmoor, NC