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Very interesting stuff about the texture of the top grain telegraphing - or not- through the finish. I'm learning a lot in this thread. Thanks, Todd, Kevin, Rick, and everybody.

Speaking of good stuff, I PM'd Kevin a few days ago about some of the questions I was asking earlier in this thread. I had a feeling he'd have some helpful experience to share if I tapped on his virtual shoulder. In his typically generous fashion, he wrote a thorough and very helpful response, and told me I could go ahead and copy it here for y'all's benefit. Here it is:


Hey Todd,
   
   Concerning your questions regarding polyester finishes being able to
prevent denting of the wood underneath, I'd have to say that it is really no
more durable than any other well applied finish in those cases.

   I have had a successful repair business that has run in waves since the
70s. If I was extremely busy building my own guitars, I would allow the
repair business to take a back burner and vice versa, but I always have
some repairs going on in my shop.

   It's my experience that the incidents in which the wood under a finish is
actually affected and either scratched or dented consititute only a small
percentage of finish repairs. Most finish repairs are surface scratches or
chips or even dents that affect only the finish so they can be easily
addressed according to the finish material.

   In the event that the wood is damaged under any finish, it's essential that
you have as deep of an understanding of the finish material that is in
place as possible. Knowing the finish is key to being able to repair
efficiently and with as little evidence of your repair as possible.

    I've done such repairs on guitars with every finish available today and
have had to be patient as I've learned their respective characteristics and
the quirky ways in which they behave when repaired.

    Poly is the most temperamental of all in my opinion since there is
never a chemical or molecular bond between the existing finish and the
repair layers, but a physical or mechanical bond. Whenever that's the
case, the most important thing to know is the preparation process before
the new repair layers are applied in order to avoid witness lines or
feathering indication.

    I usually remove the damaged finish if it is into the wood and prep the
surrounding area by sanding it to 1000 grit and then make sure that my
touch up falls well within that sanded area. Before applying any poly, I
like to use a poly sealer which will also serve as an adhesion promoter
between the new and old material.

    Once you level and pull back your new touch up, you'll be able to
feather the poly into the existing finish with very little to no witness lines.

    There is no finish that is going to prevent the denting of the wood that
comes from an aggressive strummer or carelessness, but poly has proven
itself to be highly resistant to surface breakage or scratches that will
make it into other finishes quickly.

All the Best,
Kevin Gallagher

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Rick,
   Can you explain what type of bridge is being used as you glue them
directly to the finish using CA glue.

   Is it a typical acoustic style bridge with either holes and pins or a
pinless design or is it a string through design on you solid bodies? My
question is whether the load created by the string tension is borne
completely by the glue joint between the bridge and the finish on the top
or by the ferrules in the back of the body.

   I don't know if I could have enough confidence in a CA to poly finish
glue joint to trust it under the tension of a set of acoustic guitar strings. If
that's your application, you're a braver man than I when it comes to CA
glue. If it's the latter of the two applications, I could do it since the load
would be displayed more as pressure down on the saddle and would
actually aid in keeping the bridge in place as the load is borne by the
ferrules in the back of the body and slightly by the edge of the holes
through which the strings emerge at the top of the bridge.

   Sorry, but humor me with a little explanation when you have a minute.
Whatever you're doing is obviously working on your wonderful guitars.

   Oh. I really enjoyed the ad trailers for your MTV deal. I look forward to
seeing it.

Thanks,
Kevin Gallagher/Omega Guitars

I've repaired too many Asian guitars with lifted bridges, where the finish is still stuck to the bridge, but the finish itself lifted from the top, to ever attempt it. I suspect that dep cold temperatures are the main culprit, since most of these saw exposure to deep cold. What i hate most is that the finish rarely comes off only within the bridge's footprint, but rather, it usually takes a larger area wit it. Not nice....


I know it works, but I've seen it's dark side, up close, also.


The telegraphing can also be the result of fine sanding; when we get to 320 or finner, the harder lines don't get cut down, while the softer pulpy area does get sanded. Sort of a burnishing effect. I also see it right after buffing, so either the heat generated(which does not harm the finish) or the actual pressure of my buffing causes it, but either way, i see nice grain telegraphing on all my instruments.

A note on the appearance; polyester often looks much thicker than it is, because it has this great ability t flow -to- an edge, instead of away from as nitro and waterbornes do, and this lends to nicely rounded edges and an overall "soft" look, which our mind
 sees as 'thick'.

And on repairability, my take on 'shop dings' is to completely refinish the plate. If it's the top, the top gets re-done, if the sides, the back, whatever. I just re-finish to the nearest break, usually the bindings, and don;t think twice about it. It's much faster than nitro ever was, since I can ding today, strip ad re-finish tonight, and buff tomorrow, and keep on my merry way. Takes less time, and is a complete repair.

carry-on....

The trick is in enhancing the adhesion of the finish to the wood. We do that by first putting two thin coats of Waterlox on the tops (and just about everything else) and allowing that to completely dry. In the paint industry, this is called "tie coat" as it enhances adhesion of further coats of finish. From my research it seems that the tung oil bonds particularly well to lignin, and the phenolic resin bonds particularly well to cellulose, helping subsequent coats bond to the wood.

Then we shoot on McFadden's rosewood sealer...two coats...on everything, scuff that with maroon Scotch-Brite, and then shoot on three coats of McFadden polyester thinned 25% with MEK and cured with cobalt drier and MEKP.

The only one I've had lift did so because it was not fitted properly...it was the first that one of my employees had done.   

The bridge is one of my long "stiletto" style Renaissance bridges and it has pins. I've also done this on straight pull non-pin uke bridges.   

I have to say that we do have incredibly good finish adhesion. We can rout or drill right through the finish without it lifting or delaminating.   We're going to start routing pickup holes after finish rubout on some solid body instruments; that's what they used to do at Parker Guitars in the old days.

Hey...er Grump and/or Rick and/or others...

Has anyone done neck re-sets on the Asian guitars where they have been finished with the neck attached? That fillet, or meniscus of thickened finish at the junction has always bothered me. I was wondering how you make the guitar look "right" after cutting through the finish and removing the neck.

_________________
JJ
Napa, CA
http://www.DonohueGuitars.com

I seriously doubt that it's worth the time to make cheap guitars look right.   And is "right" to have that fillet of polyester in there?   Same issue on Gibsons and Guilds, though with them it's worth a half-hearted attempt at finish touch-up. Still, there are few things less rewarding than touching up instruments that should not have been built that way in the first place.   

Yeah, I have a bad attitude about that issue...

OK then...forget the cheap guitars. There seems to be a significant number of custom builders who do this as a matter of choice. I have 2 questions:
1) What advantage is there in finishing with the neck attached?

2) How are neck resets handled?

I share the attitude about this as well but never have heard the other side of the debate. Anybody interested in expanding the body of knowledge.

_________________
JJ
Napa, CA
http://www.DonohueGuitars.com

Wow, is this ever a fantastic thread...

Thanks to Rick, Kevin, Ma..er, Grumpy and all for your contributions here. I feel like I'm getting a good introductory education on this. Great questions, great answers, fantastic information.

I'd love to hear more on Lance McCollum's 2-part material. Lance?

[QUOTE=Rick Turner] I have to say that we do have incredibly good finish adhesion. We can rout or drill right through the finish without it lifting or delaminating.   We're going to start routing pickup holes after finish rubout on some solid body instruments; that's what they used to do at Parker Guitars in the old days. [/QUOTE]

Well, if drilling and reaming through a finish won't shred it, then that's one really tough finish with great adhesion. Thanks for that great insight Rick.

This is one of those things that make me go "Hmmmmmm....." with a great curiosity.

Bar none, the most beautiful finish I've ever seen on a guitar is done by Kim Walker. I don't know much about it, but I hear it's majorly labor-intensive.

My problem? Like so many others here, I want it all...the perfect finish. Perhaps we're not meant it though, otherwise we wouldn't keep seeking and learning and experiencing new things, which just builds character in our lives.

Oops...had a small pseudo-philosophical rush there... sorry.

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

    I, too, use a tie coat that promotes the adhesion to the wood of
whatever I put over it and the material used varies according to the
subsequent coating just as you'd stated.

    For my UV cured poly from McFadden, I use something that was shared
with me by another builder who had used it for several years before me
and it really creates and aggressive bond between the finish and the wood
underneath.

    He asked that I keep it between us since he had spent loads of time
coming up with it so I'll leave it up to him to pop in here and post what it
is if he'd like. It is about as unconventional as I could imagine at the time,
but it was amazing to me how well it did and continues to work for me.

    As far as I know he and I are the only ones using it with the UV stuff so
far. He had shared it with a few of the other guys using the material and
they chose to continue with their current methods and materials and
several have continued to experience some of the typical delamination
problems with the finish.

   I do all drilling, cutting and routing on any of my guitars after finish just
because this process has enabled me to with no trouble, but I was careful
to do as much of it as possible prior to finish before to avoid the lifting
and delamination that you mentioned.

   I have several Parker Fly models and can really appreciate Ken's efforts
to get a great finish. They are my main guitars for both live and studio
stuff. Anything that they try at Parker Guitars is worth some attention.

    Now if I can just land that piece (or two) built by Rick Turner, I'll have
the ultimate guitar arsenal. Sometime in the future.

   I feel the same way about investing time into cheap guitars. It's just not
worth it so I explain the acceptable outcome to the customer and let them
decide if they want to spend more on a repair than the guitar is actually
worth.

    As far as resetting necks on overseas guitars with that smooth, thick
finish buildup at the neck joint, I cut it, square it off as cleanly as possible
that sides of the heel and level it where the neck meets the body and do
the reset. If there's a slight gap in the finish where the glob used to be
when I'm done, I make sure that it is to a similar gloss level to the rest of
the guitar and move on. That buildup is rediculous and is just allowed for
time sake in production as they pump them out.

    I finish necks and bodies separately to avoid the cutting and necessary
finish work in the event of a neck reset being necessary down the road,
but a well apllied thin finish is much easier to work with on a guitar that
was finished assembled than on one of those cheap guitars.

Thanks again,
Kevin Gallagher/Omega Guitars

The more I read about this technique with that material and that technique with this material, the less interested I am to even get involved in guitar finishing,,,,,,,,,,and I actually have half a clue about this stuff! 

A couple of my questions in this thread have slipped through the cracks, so I'll copy them here in hopes that you guys will address them.

First, for Grumpy, in reference to your first post about your experience with polyester, I asked:

Another thing you said is that it "shrinks with the top". I'm not sure if I understand what you mean by this. Can you elaborate/clarify? [Is this the grain telegraphing issue that's been discussed since?]

Can you describe what you mean by "pick tracks"?


Second, for Rick, I had a follow up question about repairing a polyester finish:

Now, thinking a bit beyond a little ding that might happen before the guitar is in the customer's possession...

Do you recommend CA for finish repairs on polyester in general - work that goes beyond drop filling a ding? For example, say I get a guitar back for a warranty repair of some kind that includes touching up the finish. Is it just as well that I continue to use CA, or would I be better off equipping (and educating) myself to work with the polyester finish material itself for future repairs?

[Again, the scenario I'm considering is farming out polyester finishing to Addam, and my question is about what I'd be getting myself into with regard to doing finish repairs on these guitars.]


Thanks!

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Re. finish repair...most problems are solved with CA. The stuff does not burn in, and you will get witness lines if you try to spot finish touch up by spraying.   I have to say that I just don't find this being a real world issue though.   I've been using polyester for about 17 years...going back to when Pat Wilkins was doing my work...and I don't get instruments back needing finish work we can't handle.   We've done some major rebuilding of necks, etc., and for those I just mask off the body and refinish the neck.   The results are fine.

Again I have to say that I think that nitro is nowhere near as repairable as folks think it is. In my real world, the repairability issue is no reason not to use polyester.   

Perhaps the ultimate guitar finish would be polyester for back, sides, and neck, and French polish for the top.

I've got an upcoming "R&D project" working with the classical guitar builder Monica Esparza...she displayed at H'burg in that island with Tom Ribbecke and Fred Carlson...and that is what I'm proposing for the finish.

She and I are going to combine 150 years of guitar making into one instrument...a classical guitar with her interpretation of the Romanillos style with my approach to engineering the structure of the guitar.

I want to combine polyester with FP on that guitar.

Rick: any reason you say poly for the neck? Simply a durability issue? Maybe it's a personal thing, but a french polished or oiled neck is far more comfortable to me than any gloss sprayed finish. I've only done 5 of each (roughly), but the difference is marked.

[QUOTE=Rick Turner] Re. finish repair...most problems are solved with CA. The stuff does not burn in, and you will get witness lines if you try to spot finish touch up by spraying.   I have to say that I just don't find this being a real world issue though.   I've been using polyester for about 17 years...going back to when Pat Wilkins was doing my work...and I don't get instruments back needing finish work we can't handle.   We've done some major rebuilding of necks, etc., and for those I just mask off the body and refinish the neck.   The results are fine.

In my real world, the repairability issue is no reason not to use polyester.   

Perhaps the ultimate guitar finish would be polyester for back, sides, and neck, and French polish for the top.[/QUOTE]

Thanks, Rick. That's helpful. In my case (farming out the finish to Addam, and not being set up to work with polyester in my shop), I suppose if I had finish repair work on one of my guitars that couldn't be solved with CA, I could send it back to Addam.

Like Mattia, I'm interested in your preference for polyester on the neck rather than FP or oil.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Polyester actually feels very nice on necks. Not grabby like nitro at all. More so than FP, for sure, but still better than expected.

'pick tracks": skid marks left by the pick scraping the top


'shrinking': yes, telegraphing of the grain lines


May as well add that this stuff can be brushed-on. I tried just for fun, and it went rather well. Harder to keep track of the buildup, so spraying is way better, but it -can- be brushed. On my FP necks(about half of them are), I brush the headplate with polyester instead of messing the gun up for such a small job if I'm not shooting anything else.

I'll also add that I've moved away from  McFadden's and now use Chemcraft's system, including their sealer, which I don't have to wait for it to dry, and scuff before the top coats. Shoot the sealer, and 20 minutes later, I topcoat directly. I find the finish dries harder(more nitro-like) and buffs to a better gloss, more readily, also.

Can't edit? WTF?

 Rick, I've had issues with a cedar tops and lifting bridges. I may try your method on one of these, next time. Do you scuff the finish under the bridge area, or do you just clean it with the acetone and glue the bridge to the glossy finish?

The volatile oils in cedar do the same thing that rosewood oils do...they prevent polyester from curing. They are the anti-catalyst.   We do one or two coats of Waterlox and then two coats of the McFadden rosewood sealer allowed to dry well before scuffing and shooting the polyester.   If you're shooting poly on barely cured sealer, the sealer may not be doing the job of locking in the cedar oils.   

I've done the brush-on thing, too, and I used to brush on a coat and then squeegee it off as a pore filler. Now I'm using West Systems Epoxy for pore fill, and it's great. I think an ideal schedule would be Waterlox, West epoxy pore fill, sand back, Waterlox, Rosewood sealer (on all wood), polyester...three coats.

I have to handle my stains and bursts differently as I cannot risk sanding back to bare wood. On those I don't use the epoxy pore filler and I do an extra day with three coats of polyester.   The first day of poly becomes the fill coat process.

Where does one find Waterlox?

www.waterlox.com

It's basically a long oil varnish with tung oil and resins. It can be used as a finish or as a pre-sealer/tie coat under other finishes.   

It looks fantastic on bridges and fingerboards, by the way.

I don't have an issue with the poly curing on the cedar, and have excellent adhesion there. But I've had a few bridges lift on the cedar, usually taking a dusting of wood with them. It could be that your method of gluing the bridge to the finish would "fix" this for me, is what I'm thinking.

I used to wait at least 24hrs. for the McFadden sealer to cure before topping, but the Chemcraft guy assured me I could top their's in 20 minutes, and I am seeing excellent results here, also, even on Cocobolo(the ultimate test of adhesion...) though I haven't used anything under the sealer(it "wets" the wood as well as anything I've seen, so i haven't bothered{yet <bg>})

Smooth or scuff under the bridge?

I just clean the buffed surface really well with superglue solvent.   A light scuff probably isn't a bad idea, though.

Cedar can be weird. The bonds between the cedar fibers and cells do not seem particularly strong.   I do think that doing a finish on it like this may help achieve the strongest bond, though, as the Waterlox is really bonding into the wood.   

I see this process as being analogous to really high quality chrome plating on steel where they first lay down copper, then nickel, then the chrome. Each layer bonds particularly well to what is under it, and any porosity in a layer is taken care of by the next.   Chrome directly on steel works...for a while...and then chips, peels, and flakes off.   

Thanks, Maestro.

Careful with that...Maestro Alex Gregory will come after you and sue you for using his name in vain! He patented the seven string guitar, you know...

Google him...

A character...

Actually, what would probably work great would be to mask the poly finish on the top, cut out a section slightly smaller than the bridge, and lightly bead blast it. Or it could be CNC laser etched. That's what they did on the carbon fiber fingerboards on Parker Fly guitars...laser etched the bond line.

Sir Grumpy:

If you would, what Chemcraft product are you using?
I see pre and post catalyzed, as well as a reslack polyester. Sorry to be dense.

Thanks.

_________________
Eagles may soar, but weasels don't get sucked into jet engines.