Official Luthiers Forum!

The feedback from the gentlemen on General Finishes EnduroVar II (EV2) is that while the manufacturer dramatically improved spray finish handling, they unacceptably altered coat-to-coat adhesion and wetting characteristics such that the stuff far less attractive for guitar work. While the initial coupons done with EV2 showed much more lacquer-like spray behavior and less amber toner (a real issue on some woods), further use and some cedar and redwood-topped projects revealed the issues noted below.

- The window in which to recoat without sanding is much, much smaller... if not done immediately upon flash-off, failures of adhesion and witness lines were seen in well-dried samples. Original EnduroVar (EV1) tolerated recoats within 60 to 90 minutes (depending on temperature and RH) without binding problems, allowing a two day application schedule when sprayed. With EV2, the short reapplication window suggests sanding between every coat, which drags out finish application to a week or more.

- Wetting characteristics of EV2 were changed such that color on clean cedar or redwood tended towards a mottled appearance. EV1 wetted out more evenly on these woods.

- Sand-out and buff remained about the same, with initial leveling within 48 hours desirable to avoid the chore of the bulk of the sanding done when fully hardened.

In summary, Mr. Greven's EV1 schedule and techniques appear to be less than fully applicable to EV2, and the boys are working up High Performance as a possible replacement for neck and waterbased refinishes.

_________________
For the times they are a changin'

- Bob Dylan

Bad news for me, my favored finish.
Good job I'm working on a cunning plan....

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Are they still making EV1 available?

Thank you for sharing your findings.

M

Woodie,
Thank you for the information on EV2.
I found that with original Endurovar recoating when just dry to the touch and before the finish had cured gave better results than allowing the finish to cure and fully cross link. When I did a recoat on a neck a few days after original application - even with scuff sanding the finish did not stick to the old very well.
There are no perfect finishes. Learning their application and limitations is just part of being a finisher.

Thanks for the info on EV2. I've been hoping to hear some firsthand experience with it.

Do you have an opinion about how their observations with spraying EV2 might bear on brushing it on?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Thanks Woodie,
I've learned so much from you and you have always been gracious enough to answer my questions.

Just an empirical assessment from a small batch of 15 ukuleles that have had EnduroVar II (4 coats) and High Performance (4 coats) on top of that. And ,oh yes, they were over 3 coats of Silvertip epoxy pore filler. The finish has been on about 4 months now and I have not experienced any adhesion problems that I have noticed.
I brushed the finish layers on with a foam brush and allowed about 50-60 minutes in between coats. They were placed in a temperature controlled closet at 77°-79°F between coats and for 24 hours after the last coat.
I did wait 2 months before finish sanding the instruments and buffing them. Also, two of the ukuleles had Redwood tops.

Anyway, I certainly don't claim to know all the answers, but so far so good.

_________________
Formerly know as Mandodiddle.

I am using endurovar 2 on two current builds and am just finishing with the last coat. I did notice that it sprays pretty well (similar to em6000 that I used on several guitars). I followed the instructions from General of allowing to dry 2+ hours between coats and then lightly sanding with a nonwoven pad or fine sandpaper and things seemed to go well (though it is tough to judge the thickness of the coats).

I do have a question for those with experience through cure and buffing though, and it deals with witness lines. In leveling the coats I noticed a time or two where I sanded through one coat and into the next I would get some witness marks. Has experience shown that these go away when doing the final buff (Menzerna compounds on an arbor buffer) or will they still be evident? I have seen them stay or go depending on the finish so it would be nice to hear from prior experience to know what to expect.

Can't vouch for EV2. But I have buffed out EV1 after 2 months drying of first coats without witness line (sand through).

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

That's pretty concerning that both you and Woodie are reporting seeing witness lines with EV2. I haven't seen any at all with EV1.

I hope someone can answer your question as to whether witness lines go away or not with the final buffing.

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Why did you go with 4 coats of High Performance over the EV2 rather than use EV2 for all the coats? Does the High Performance finish have some benefits over EV2?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

J, I basically got this process from talking with John Greven. The EnduroVar II goes on a little thicker and gives the wood a slight amber tint (which I like). The High Performance goes on a little smoother and is a tougher coat, both physically and chemically as I understand it.

_________________
Formerly know as Mandodiddle.

When John Greven gave a presentation to the Seattle Luthiers Group just about four years ago, he didn't mention using High Performance so maybe that's a recent addition to his method.

Were the witness lines you saw when level sanding between coats just in the EV2, or did you see them when level sanding the High Performance too?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I will just add this. I have seen some witness lines, but they seem to buff out nicely. I really don't know if it was in the EV2 or the HP. My guess is it was when I sanded through the 4 coats of HP and got into the EV2.

And maybe I'm missing something (probably), but couldn't the witness lines be taken care of by just applying the next coat sooner?

_________________
Formerly know as Mandodiddle.

Yes, I've sprayed EV1, like that - 3 base coats, level, 3/4 top and B&S, leave to cure, level and buff.
But I've also left some coats for several days or more (up to about 3/4 weeks) but with a full sand, (not just a scuff) before successful re-coats, no adhesion problems.
- I hear that!

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Here is a brief article by one of my favorite finishing pundits, which may obliquely explain why recoating water based finishes before they have fully cross linked may not be a bad idea, and possibly reduce "witness line" problems:
https://www.woodshopnews.com/columns-bl ... durability

Hi Colin,
When I recoated a fully cured EV1 finish I just scuff sanded the old finish. Fully sanding the the surface as you did is probably a much better way to go - it may provide a better "toothed" surface for the new finish to mechanically bind to.
I will apply several coats one day, not allowing the finish to fully cure between coats, let it dry overnight, level sand it the next day, then apply several coats the next day, again recoating before the finish fully cures between coats, then allow it to cure before sanding and buffing. When doing the final sand and buff I don't think I am cutting through the second day's coating.
I have only used EV1, so EV2 may behave differently.

At some point before my current supply of EV1 runs out, I expect I'll do some testing of EV2 as a brush-on rather than a spray-on finish. I know what to look for with regard to witness lines, but I'm wondering what to look out for with adhesion failure. Do you know how it presented itself when they did their testing of EV2? Would it be something like the finish lifting and forming blisters? About how long after application did the failure take to show up? Did the adhesion failure happen passively with the test panels just sitting there or was some sort of mechanical stress required to get the finish to fail?

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I once saw a video of a finishing pro aggressively test a panel for coat adhesion by taking a knife and scoring the panel in a checkerboard pattern, then pressing down strips of duck tape and ripping them off.

Ok, that makes sense that a mechanical test like that would be used. I don't have a sense of how strong finish adhesion is typically. I wonder if most or all finishes used on guitars would be expected to have no problem passing a test like that.

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

If duck tape can pull off a layer of finish, I would think that would be a problem. It might be OK for a few years but eventually it would start peeling off in high wear areas.

Conversely, if nothing peels off with the tape, you could assume that you've got good adhesion.

I will see if there are some photos of the test coupons and the classical that was refinished recently. My understanding was that the refinish went well, but the time between coats was kept to a bare minimum (a few minutes between the last flash-off and recoat, so perhaps 30-45 minutes between coats). Despite that, the final two coats on the guitar were sanded off due to multiple areas of adhesion failure... no apparent reason. As a result, the final finish thickness was less than the targeted 2.5 mil before buff-out.

_________________
For the times they are a changin'

- Bob Dylan

I’d be quite pleased with less than 2.5 before buff out, as long as it didn’t burn through…

Yes, Woodie G, please show us and let us know what is going on.
Thanks

_________________
Formerly know as Mandodiddle.

Just an update. As long as I stay in the High Performance layers the finish looks great. However, if I finish sand through the top 4 High Performance layers and get into the Enduro-Var II layers there are definite witness lines that will not sand out. The good results I got earlier are when I stayed in the High Performance layers.

_________________
Formerly know as Mandodiddle.