Water base finish effecting top and back seams

[Bryan Bear]

I am trying a water base finish (poly whey) for the first time and having some trouble. Anticipating problems with water, I sealed with a few spit coats of shellac so I am confused as to what is going on. The finish is building fine and I’m happy with it so, though I'm still getting used to it. The problem is that all the plate seams, which were joined with HHG, are showing a distinct line in the finish. The joints are good, without the color/grain change, I couldn’t locate them by eye until I started finishing. Obviously, water is getting into the wood and swelling it. I assume the joints themselves are not compromised, but I am not sure if I should keep building and then level sand, or if that will cause more problems. How long do I need to wait before I level so that I know moisture is equilibrated? After I level sand, I will need to do at least one more coat (won’t I?) will this just reintroduce the problem (or is the problem caused by the first application and sealed thereafter)? I know a lot of you have used various water based finishes before (not necessarily poly whey), how common is this problem and what are the solutions?

[Rodger Knox]

Did you raise the grain before/while you were doing the shellac? A thin coat of shellac will usually raise the grain some, and then I sand that smooth. The second coat may rasie the grain a bit also, if it does I sand that smooth and put on another coat. I haven't done any water based finishes, so I can't help with that.

[Bryan Bear]

Well Rodger, I actually changed horses mid stream (I'm fighting a deadline and doing all the things we warn against, like testing on the instrument).

I first tried egg white pore fill for the first time ever, that raised the grain but had no visible effect on the seams. I needed to do another session but I instead decided to do a pumice pore fill. I did my wash coats and any grain raising was ground down during the pumiceing. Again, no problem with he glue lines.

[Randy Roberts]

How long did you let the seam dry before you sanded the top down?

If you sanded soon after joining, or if you had humidity fluctuations between when it was joined and when you sanded, the glue may have contracted some more after sanding, or the wood may have swelled thicker in relation to the glue after you sanded.

[Bryan Bear]

The plates were joined for at least a week (likely more) before they were thicknessed. I have heard of problems with that very thing and even though I have never experienced it, I always wait a good deal of time.

[Bob Gramann]

I've had the same problem with some woods (particularly Sycamore) and Target EM6000. I've level sanded the finish and resprayed 3 coats. Sometimes, the grain raises again even though it's under 12 coats of finish. I let it cure for a few cays and level it and polish it. Generally, there's no further problems. Good luck.

[Bryan Bear]

Tonight I will level sand everything again and see where I end up. I'm not sure if I should do more shellac after I level or not. I'm considering gong down to bare wood since it builds well enough.

[Michael Lewis]

Apparently your wood is not sealed. You need more than a 'spit coat'.

[Barry Daniels]

The problem is that if you sand level, you will probably remove all finish on the raised glue line so the next wet coat you lay down will possibly swell the glue line yet again.

[Bryan Bear]

Barry, I'm not sure it is the glue line that was raised or if it was lower than the surface. It is so thin that I just can't tell; I can see it but even dragging my fingernail across it, I can barely feel it and can't be sure if it is a bump or a valley (my guess is valley).

Last night I sanded back to level and am moving forward. Once I got it level, I did two more shellac sessions. Once that was dry, I did a very light test coat (of poly whey) on the back. The coat was so light that it wasn't even enough to really self level. The good news is that i don't see any evidence of the joint this morning. The surface looks rougher than it did before though due to the unleveled coat. I put a similar very thin coat on the top this morning, we will see how that looks when I get home. I'm hoping that I can get another very thin coat or two on and then knock it back with some 400 and proceed as normal. Fortunately, I didn't sand through to bare wood when I leveled.

[Chuck Tweedy]

Barry, I'm not sure it is the glue line that was raised or if it was lower than the surface. It is so thin that I just can't tell; I can see it but even dragging my fingernail across it, I can barely feel it and can't be sure if it is a bump or a valley (my guess is valley).

Then you just did not have enough build to hide the joint. You might be over thinking this...

[Bryan Bear]

Then you just did not have enough build to hide the joint. You might be over thinking this...

'Tis possible, I have been accused of making things more difficult in the past <G>. I'm not sure I take your meaning though. I had done a pumice pore fill and there was no trace of glue line. If the offending line was a valley (as I think it was), I'm not sure why it would build differently there. It is possible that more coats wold have filled it, but why was it there? If it shoes up again, perhaps I'll just build more and level, then polish. Hopefully, it won't return.

Still, I'd like to know what happened so I can avoid it in the future.

[Gordon Bellerose]

I use waterbased products in my shop. I live in Canada and we have a lot of trouble finding a lot of oil based finishes, because of anti VOC laws.
I find that any flaw in the woodwork gets magnified a lot, under the clear coats.
I had a small crack in a maple solid body that I couldn't see until I had about 3 or 4 coats of clear on it.
Had to sand it all off, fill the crack and start over.

I'm not saying your wood work was flawed, just saying that he waterbased clear acts like a magnifying glass.

[Bryan Bear]

This is a good time to update this project/problem. The charity this is intended for is an on going fund raising effort and we decided to just put it off until the next raffle so I would have time to get the finish to my satisfaction. Armed with more time, I continued to build more coats and not worry about the seams for a while. I built up to a point where I knew I had much more thickness than I wanted for the final finish. But for the seam issues, I was really liking the gloss this product gave. Then I let it set for a week or so. Yesterday I level sanded the top and back plate. The seams are now once again completely level; you have to follow the grain to even find them. I'm not really sure what was going on, it seems like the area of the seams were repelling the finish but not totally. Once the tiny ridge was sanded away, there is ample product over the glue line.

Now I have to face a new learning curve. I've only used tru-oil or FP up until now (with FP being what I have the most experience with). Level sanding and bringing back the gloss is new to me. I leveled to 600 and got the finish nice and thin but naturally the gloss is gone. I polished a small section of the back with my micro mesh pads from stew Mac up through 6000 and buffed by hand with mcgwires 7. That area is nice and level with a soft sheen. It is not nearly as glossy as the product was before I sanded. So I have to either figure out a schedule for bringing the gloss back up or try to come back and leave one final perfect coat. This is looking like it is going to be just as (if not more) time consuming than FP. The work is easier on the shoulder but more tedious. At this point, I'm not sure which way I will go in the future.

[Bob Gramann]

With EM6000, I use P800 paper to level, the LMI fcut polish to start bringing back the sheen, and the StewMac swirl remover to get to final gloss. The sheen is limited only by my patience. That said, I'm usually happy with a less than glass shine.

[Bob Menzel]

I've been following some very interesting forum discussions here, and there, about finishes. These discussions have led me to read everything I can find on the topic, and though I've only seen the tip of the iceberg, my head is swimming.

Not sure where I read this but regarding PU's (oil or water based) it was 'suggested' that they will never be as glossy (after rub out) as they were after the last coat has dried. I don't take that to mean that you can't get a really nice finish with them, but from what you guys are saying, you've got to put some effort into it.

Bryan: How would you compare Tru-Oil and Poly Whey: from the stand point of finish appearance and the time and effort it took to get you there?

[Bryan Bear]

Bob, I would love to answer your question about tru-oil v. poly whey, but I just can't formulate an informed response. I have learned a lot since I last used tru-oil and my results and expectations are better now across the board, that coupled with not yet having completed anything with poly whey makes it too much of an apples to oranges conundrum. Please take the following comments with a huge grain of salt as most of it will be speculation based on too few data points and general impressions.

Work involved - I would say that tru-oil was perhaps less work inasmuch as I didn't Do a lot of leveling after final wood prep. I knocked the tru-oil back with steel wool between coats but that was no big deal. I just kept adding thin coats until I gave up and called it done. I was too afraid of witness lines to do anything else. I will say that it took way longer to build up a finish because of the wait time between coats. With Poly whey, I could lay on a ton of finish in a day or so because it dries pretty quick. I was however unable to get really nice even coats; it goes on thicker than tru-oil, it does level out nicely but I still couldn't get a totally even final coat. Also, it took some getting used to to avoid drips and runs on the curved sides. I would say all of this was my own fault for having bad technique though. The real extra time for poly whey looks to come in the form of leveling and buffing. Again, my lack of experience will be a big factor.

Appearance - Too early to say. I feel like the Tru-oil allows for a warmer and deeper look, but the trade off is that my final surface (back then) was not as good as I would want now. Poly Whey had a nice gloss before leveling and I liked the look, even if slightly less than the deeper looking Tru-oil. It looked a little bit more dipped in plastic than the natural depth of Tru-oil, though it should be noted that I was going intentionally thick at that point to allow for a lot of leveling. The problem is that I'm not sure I will be able to get that shine back. If I could have the final finish as glossy as it is when dry, but as level as it is when sanded, I would happily trade it for the Tru-oil look.

You didn't ask but durability - It seams like the poly whey might be a bit more scratch resistant but I can't say for sure. The reason I wanted to try this product is because I wanted to have another weapon in the arsenal for instruments that are unlikely to get the care that FP deserves. . .

Hopefully I'll get the hang of polishing this back up. I'd be lying if I said I hadn't considered doing FP on top of it. This of course would be totally throwing in the towel and negating the whole purpose of using Poly whey.

[Gordon Bellerose]

I have used water-based clear for all of my builds. The way I get the gloss look is this way.

While I'm laying the clear coats on, I scuff sand with 400 grit every 3 or 4 coats.
After about 12 coats, I put the guitar up to cure for a week. The reason behind so many coats is that water-based lacquer builds in layers much thinner than oil-based.
I start wetsanding with 600 grit , then go to 1000, and then to 1500.
At that point I go to stewmac medium buffing compound on a foam buffing pad.
Then I go to fine, on a new pad, and lastly I use swirl remover on yet another pad.
The finish comes out with a really deep gloss finish.

[Bryan Bear]

Update:

Life happened, this has set on my bench alone since late August or September, I honestly don't remember when I last worked on it. Last night I broke down and sanded much of the finish off. I was hoping to get it down to just a very thin layer that I could just french polish over (leaving the poly-whey in the pores to save a bit of time). A wipe with naptha revealed a few spots sand throughs. so how to proceed? I see the following options:

1) Seal with shellac and french polish (I assume that will not hide the sandthroughs but wishful thinking and all that. . .).
2) Go to bare wood every where, and french polish.
3) Seal with Poly-whey and FP over that.
4) Give Poly-whey another chance. I really wanted to like this stuff. I would love to have a non FP option that doesn't require spraying and horrible smells. I don't want to give up on this product if the only real reason is my incompetence/inexperience with a new technique. That said, I have had a few problems with it so far and cringe at the thought of sanding it down again!

Thoughts?

[Michael Lewis]

Bryan, have you thought about brushing oil varnish? No special tools required, and it makes a durable and attractive finish. It does smell for a bit but there is no water in it to swell your wood and make it distort. Epiphanes CLEAR GLOSS VARNISH has proven to be a reliable and quick drying solution for finishing. Use the cheap foam brushed and throw them away after each coat. very nice finish.