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Hello All

I have been using this product lately and I can't get constant results with it.

I was wondering if anybody could share their sanding technique, which is of course the key to success. Here is how I do it:

-I apply the lacquer by brush, over Z-Poxy.
-I apply about 9 coats, then rough sand with wet or dry 400 grit (with water) after a 24 hour wait.
-I apply another 3 coats, then let dry for 10 days.
-I wet sand starting with 800 grit, up to 6000, no buffing (I don't like power tools...)
-I finish by applying a product called "Nu Finish", which gives a pretty good shine.

The problem is that sometimes I get visible sand marks, which seem to be 400 grit leftovers. This seems strange because I applied more coats after the 400 grit sanding, and the product is suppose to "burn in" with the previous coats, which would in theory make the 400 grit sanding marks vanish.

A couple of points about my sanding technique:

-I use tap water with a few drops of dish soap in it;
-I use a hard rubber sanding block at first, then move to the soft foam block (the one that comes with the Micromesh kit)
-I sand with the grain only, at every grit.

As I mentionned, sometimes I get sanding lines (with the grain, which is my sanding pattern) visible.

I would like to know about your techniques if possible, with regard to things like:

-Sanding patterns (with the grain or in cercles)
-Sanding sequence
-Glossing techniques.

Looking forward to reading about your experiences with this product, or any other waterboarne finishes.

Cheers

Pat

One possible explanation for the 400 grit scratches- Ultima shrinks back a lot, so much that three thin coats may shrink down into the scratches left by the 400 grit paper. It seems like three coats should be enough to fill them in, so i dont know if i trust my own theory, but USL lays down and sands so easily that i usually do pretty much all my sanding wth 600 and finer paper.

I have not brushed on an entire finish, but i do often use a brush for little touch ups, and i have come to the conclusion that USL does not like to cooperate when i brush it on. KTM-9 brushes on pretty well for me, but i always have a mess with USL.

Your schedule seems fine, one thing i do differently is i sand perpendicular to the grain every other grit, ending up with the grain. It is really easy to see if there are any scratches left running at right angles to the ones you are making with the current grit, no scratches hiding with the grain waiting to show up in when everything is super shiny.

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Ithaca, NY

Hum.......one thing I notice in your schedule is this



That is a lot of coats (by brush none the less) to be sanding after only 24 hours. My guess is that the lower coats have not even off gassed or cured enough in that time frame to sand well.

This of course does not explain your sanding scratches issue.

I would do less coats in a day, like 3 max by brushing, I spray 5 max a day, if I have the time, but usually only 3. Next day, do a lite scuff sand, just to knock any dust or nubs down, than apply another 2-3 coats. Repeat this till you have done 8-10 coats. Let that site for at least 1 week, and longer is better. Than do your level sanding and buffing. Brushing usually applies much more material than spraying so you should only need the 8-10 coats total. I usually spray 13-15 coats and it gets pretty thin once the leveling is done.

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Hi Pat

I am in the process of trying USL for the first time and I'm experiencing some
of your problems exactly. I'm in my 5th week of trying to get past this point.

The guitar in question is my take on a Martin Norman Blake, Engelman top
Wenge back & sides.

I filled pores with Mirror Coat, finishing with a thinned coat of same.
I'm working in a basement and as I am not set up for spray yet I opted to apply
by foam brush as I saw Robbie O'Brien do on his DVD.

Here's the schedule
Applied 9 coats, with a few light leveling sands included.
Hung for 2 weeks.
Jeff at Wood Essence said it should rub out well dry so I
leveled with 800 then 1000-1500 with Mirka paper (on the same Micromesh supplied block as you)
Then moved through the Micromesh to 12000.
It looked very good on the bench until I picked it up and looked along the finish while facing a window.
I saw exactly what you were in terms of sanding scratches.
Went through the whole sanding schedule again, same result.
At this point I was cutting through in a few tiny spots.
Another observation was that at some points the finish started acting differently. It seemed to soften
all of a sudden, it would show fingerprints that didn't want to come out and it was impossible to get
a consistent sheen.

I phoned Jeff for advice and he seemed to think that I didn't have enough coats on top of the last sanding
I did. He suggested 3 more coats. He also indicated that if the finish started doing strange things to let
it hang another day or 2.

So I McGivered a spray area and set up to spray using a CH gun that I already had and Jeff felt would be OK.
I should say at this point I have close to zero experience with spraying, but managed to get 4 reasonable
coats applied, "orange peely" but fairly level.
I have let this cure another 2 weeks and began the rubout yesterday and I can't say I'm feeling all that confident.
I'm up to 1500 on the back and dang if the finish start going snaky on me again, so I set it aside.

It would seem that there is a common denominator in our problem.
It would be cool to fig. it out, I for one am beginning to regret opting for USL
over my initially intended Tru Oil.

A few more questions & observations.

1. My shop is fairly cool I keep it in the 60-65 range and humidity 45-50%
2. I find it hard to verbalize what I'm seeing, but it seems the scratches left
from each grit are coarser than they should be.
3. At what grit should scratches be hard to see?
4. As I wanted to give this a try, I only ordered a quart. This meant, I believe, I got USL
rather than EM6000, which I would have received in a gal. At least it's labelled as such.

Hope this is helpful in some way Pat.

Later
Bob

I forgot to mention that those 9 coats are applied over a 3 day period.


Bob said:


That seems to be exactly what I am experiencing, but not on every guitar

I am going to try different sanding strategies today and see how they turn out.

Pat

Bob,

I'm no finishing expert so take this with a grain of salt.......but if your sand down through your finish to a point where your finish is soft, I would worry that a) my first coats hadn't cured enough before applying another coat over them or b) that I had either some kind of incompatibility or contamination on the surface or introduced by the gun, sandpaper, etc.

I'm curious, is your sandpaper sterate free? I'm unsure if this matters or not but I'm curious.

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Hi Darryl

Thx for the reply.
I think coats were OK as far as dry, 3 coats a day, should be good
according to the manufacturer.
As far as the paper goes I used Mirka on the same suppliers advice,
but I don't really know if it is sterate free. Good question! I'll find out.

Later
Bob

Hey Pat

I'm wondering about sanding to 1500 then going to
Meguiars #'s 4,2, & 9 mirror glaze polishing compounds?

Any thoughts?

Bob

Eureka!!!!

I tried all sorts of sanding tips and suggestions, to no avail. I was still not happy with the results.

I then decided to sand down the whole guitar and start anew. Bummer...

I thought that as long as I was going to start over, might as well experiement a bit on the varnish, since it was going to go anyways. I divided the back in 4 sections, and started to work.

And the answer is : You gotta buff, man!!!

Here is how I managed:

-Sanded dry with the grain with 800 grit (3M Wet or Dry, the stuff you find in the auto care centers).
-Then went to 1000 and 1500, still dry and with the grain.
-2000, wet and in circles until I could see only circle sanding marks on the surface (I guess with the grain would have probably worked to, but I'll stick to this for the moment)
-Finally, took out the old foam buffing pads and buffing compounds I got from Stew-Mac a couple of years ago. I had tried it then a couple of times and it didn't really work for me then. Since I knew that this was an experiment anyways, I decided to apply more pressure than I did back then (my fear of buffing through the finish was gone, since I knew it was going to be sanded out anyways).
-I used the medium compound first, and after a couple of minutes I noticed the circle marks started to disappear. I carried on until they were all gone and then went to the fine compound. A nice and shinny surface started to appear, with no sanding marks at all. A little bit of New Finish polishing compound to top it off, and there you have it! A excellent, high gloss and sanding mark free surface.

Since the finish was starting to get a little thin, I decided to level it with 800 grit all over. I am going to let it rest until tomorrow and then start applying 3 coats a day for 3 days, then let dry for at least a week and then go through the process I just described. Hopefully it will come out as it just did.

I guess circumstances are forcing me to join the "buffing crowd" after all...

I hope this will help you get good results as well. I will give you an update when I proceed further in 10 days or so.

Cheers, and thanks to everyone for the advice.

Pat

I'm glad it worked out for you Pat.

I unfortunately have to disagree with you on the "buffing is the answer" though. It's very important to make sure the larger sanding scratches are totally removed by the next level of sanding/polishing.

If you start with 400 to level, than all the 400 need to be removed by the 600, than the 600 by the 800 etc... all the way up to the polishing/buffing stage as that is also just a refinement of the scratch pattern (on a microscopic level)

I bet you were more diligent in your sanding this time around and that's why you didn't get any former grit scratches appearing.

Polishing compound will never be able to remove a 400 grit sanding scratch. It's just to fine of a scratch pattern.

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I agree with Rod for the most part but it is possible to remove 400 scratches with 800-1000 ect but to do so would be so much work that you would get frustrated before you got there. it is by far best and easier to be diligently progressive in your level sanding. Far less work in far less time.

I agree Michael that one can remove 400 scratches with 800-1000 but that usually makes for slight dips in the finish and one can also find themselves with the great pleasure of sand through trying to get rid of that 400 scratch (I know because I've done it )

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"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

Rod said:



I totally agree with the part about removing all the scratches from the precedent sanding level. Been doing that for years!

Somehow, this problem occured when the scratches from the early grits seems to reappear further on down the road. This seemed to be compounded by wet sanding, which normally leads to the opposite (from my experience, it just makes it easier to remove previous scratches). Although I normally go the French Polishing road, I have used waterbased lacquer on at lest 6 or 7 guitars before and for some reason, my previous sanding routing would just not work on this one. I have finished without buffing before and the results were fine. This time, it just wouldn't work.

I am sure that there is an explanation for this, but in this particular case buffing seemed to be the cure. I am sorry if I offended the good folks who would rather keep buffing out of the equation (I know, I was one of them until just a few hours ago ), but I guess this old dog is not quite old enough not to learn new tricks. As for the records, I still have a few misgivings about using a power tool on a guitar at the late stage of the game, but I just learned that it can be done successfully if the situation requires it. This is a win/win situation

Ciao

Pat

FWIW

Buffing using a RO buffer and Maguiars compounds #4,#2, and #9 swirl remover
after sanding to micromesh 4000 corrected my problem.

Also strange finish behavior was indeed corrected by hanging another couple of days.

Cheers
Bob

This post is well timed as I'm at the same point.

The one thing I can stress is patience.
USL seems to be an extremely forgiving finish, but it still requires some skill and a TON of patience.

I'm not quite at wits end with the learning curve on this finish system, but overall, the things I'm learning are going to REALLY help with the next guitar.

Five weeks seems like an eternity to get a finish applied, but if you want perfect results, then that is what might take.
The next one will surely take less time.
Just remember to write everything down and share everything here so someone can find it in the archives when they get to this point somewhere down the road.

My issue was in sanding before a session was fully cured. Three days should do it. I sanded at two and the dreaded blue haze formed. It wasn't a big deal, but I did have to shut off the lights in the shop and put it away for another day.

As for the forgiveness level, I found a few spots where I sanded through to bare wood (long story about the results of a sprayer issue after two weeks of spraying and leveling on the final coat, don't ask.) If I hadn't worked with this stuff before I wouldn't have known that I could just reseal it with shellac, brush a few swipes of finish on with a cotton ball, let it cure, level it off, repeat the cotton ball trick the next day and make it look like it never happened. AMAZING burn in properties! It was a pain in the butt, but I'm glad I didn't freak out and try to sand the whole thing down to start over.

By the way, the longer the cure, the better this finish buffs out.
I had an issue with one I did about a year ago and finally got around to dealing with it a few weeks ago.
After drop filling a couple pores with CA, I resanded, and rebuffed the whole thing. It looks better than EVER.


Dave