Wiping varnish smoothness?

[HogTime]

I'm practicing on some test wood before staining and finishing my F5 build.

I've tried some Formby's High Gloss Tung Oil Finish (more accurately a wiping varnish, I've read) and like how easy it is to use. After about 12 coats on my maple test piece it has a nice gloss, looking straight on. However, at an angle I can see surface imperfections in the teeny grain features of the maple. It's also not as smooth feeling as some KTM-9 I brushed on. I'm assuming the thickness of the varnish layer is not enough to fill in the grain "valleys".

I started off rubbing the varnish in (like waxing a car), as the can says. Later read a web article that said just to wipe it on in a single pass. I did that the last few coats.

Due to my inexperience, I'm trying to stay away from spraying or brushing KTM-9, due to probable runs or brush marks.

I wonder if 12 coats (or more) of wiping (vs. rubbing) the Formby's would give me a smoother and acceptable surface?

Thanks,

[sunburst]

The surface is the wood. What I mean by that is; a wiped-on finish will follow the surface of the wood, not level it. A finish that is applied and sanded between coats can level the surface, but it is the sanding that does the leveling, and if you are simply wiping on successive coats of finish, it will always follow the wood surface and never level it.

[multidon]

If you want a perfectly smooth surface using that type of wipe on finish I believe you will have to apply some kind of grain filler first. Try that on a piece of scrap. There are different theories on what to use for grain filler; LMI, Stew Mac, and others sell a couple of different kinds. I used a wipe on varnish on a mahogany backed mandolin once without grain filler; It leaves the surface looking like it's full of pores. On this particular mandolin, a flat top, I liked the look. I don't believe it would look right on an F style though.

Here is some information on one type. Note that they use a dark color on a light wood to make the grain "pop". Never tried that though.

http://www.stewmac.com/freeinfo/Fini...es/i-5035.html

[Bill Snyder]

I would not think a grain filler of any kind would be necessary with maple.
Try hitting your test piece with some very fine sandpaper and put on a few more coats.

[Audio Artillery]

I would not think a grain filler of any kind would be necessary with maple.
Try hitting your test piece with some very fine sandpaper and put on a few more coats.

That's my thought too. Did you scrape or sand? What grit?

[HogTime]

Thanks for the comments.

My test wood is a flat piece of maple. Before putting on TransTint dye (mixed with water). I sanded with an orbital sander, using 100, 120, 150, 180 & 220. After the TransTint was applied I sanded with 220 to knock down the "fuzzies". Between coats of Formby's, I sometimes lightly sanded with 220.

I'll try a few more coats with some sanding in between.

Even though in this case, a picture isn't worth a 1000 words, here is my test piece. Two TransTint colors. Left 2 are 3 coats of KTM-9, right 2 are 12 coats of Formby's.


Thanks,

[Clinchriver]

I would have hand sanded with 320 with the grain before staining. On finish 600 is a good place to start and you have to be very careful not to sand through. Good luck finishing is the hardest part.

[Tavy]

220 definitely isn't far enough. I wouldn't use an orbital sander for anything other than rough sanding either - you want to sand with the grain to minimize the scratch marks. Most folks aim for 400 grit when applying something like shellac (which will fill anything finer than that), but for wipe on finishes, I would go right through the grits to 1200 or so - get the wood really really shiny smooth, and then apply the wipe on finish. Lest your heart is sinking at the thought of the work, be assured that it doesn't take much time for each level of grit, and when sanding by hand, don't go at it hard or you'll just make deeper scratches that'll need polishing out with the next grit - let the paper do the work!

[ardbeg]

Might be worth trying "Micromesh". It gives a wonderfully smooth surface, if you go through the grades as instructed.
I used Tru-oil to finish and was more than happy with the results.

[sunburst]

I sand to 220 before finishing, 320 at the finest. Anything finer is a waste of time... unless the finish is a very thin, "open pore" oil or oil varnish, and I don't do that on instruments.

[Tavy]

I sand to 220 before finishing, 320 at the finest. Anything finer is a waste of time... unless the finish is a very thin, "open pore" oil or oil varnish, and I don't do that on instruments.

That's what the OP was using - wipe on Tung oil - for shellac and other "thicker" finishes that flow into any sanding scratches I agree that sanding finer doesn't make much difference.

[sunburst]

Sanding scratches on the surfaces of most of the woods we normally use for instrument bodies and necks, thoroughly sanded to 220 grit, are no more obvious than the pores in the wood.
The OP is trying to figure out how to apply a smooth, level finish, and all the sanding in the world with the finest grits available will not sand away the pores in the wood. We have to decide on an pore finish or a full finish that fills the pores. In either case, 220 is enough, but for the open pore type finish, going to 320 can help.

It is very easy to, and common to not sand thoroughly. Many times the reason people think sanding to very fine grit paper is needed is because they haven't sanded thoroughly enough with the previous grits so they are still removing damage in the wood surface from previous milling, scraping and sanding procedures. The extra time spent with the finer grits could often be better spent sanding more thoroughly with the earlier, coarser grits. They cut faster and remove the damage to the wood surface faster and with less effort. I, for one, do not particularly like sanding, so I'd rather use coarser paper and get the work done faster and stop at the coarsest grit that achieves the desired result. For me, 220 is always enough for spruce and maple, and it's overkill for walnut, rosewood, or anything else with larger pores.
The way to determine that, BTW, is to prepare many samples of wood and sand each piece to a successive sandpaper grit. Finish all the pieces completely and then examine them. At some point, there will be no further improvement in the quality of the finish, and beyond that sandpaper grit, time and money is wasted. Many guitar factories have gone through that process and most of them find that 220 grit gives them the results they want.
The exception I mentioned above applies to situations where the wood itself is polished and a very thin coating is wiped on, or no applied finish at all. Fingerboards generally look fine sanded to 320, mandolin bridges, I sometimes sand to 1200 and then buff the wood itself. That is not the kind of finish I apply to instruments.

[HoGo]

Perhaps you need some grain rising. Wet the surface lightly and let dry thoroughly, then lightly sand again, repeat until very little grain shows back (some folks repeat up to 7 times, but twice or three times should do). Typical mistake of beginners is pressing too hard with sandpaper and grain gets compressed and lifts back when you apply your finish.
Yiou may consider layer of french polish on top to smooth things down...