EM6000 acting weird... or I'm an idoit?

[Ryan Mazzocco]

I've just tried using EM6000 water borne acrylic lacquer for the first time. I've seen other instruments with it and it is beautiful. But I seem to be having some issues with it. I spent a couple days with Joe Mendel and he gave me a step by step tutorial a couple months ago but my results are not nearly as nice as his.
I sprayed it on 3 guitars last week, but really only seem to be having this issue on one. It's a torrified sitka spruce/Black walnut dread. As per Joe's instruction, I applied 2 coats of shellac (Zinsser), waited overnight, level sanded, then sprayed 10 coats of EM6000. Today I started sanding and noticed that there seemed to be deep pits and ravines in which the wet sanding slurry collected and turned an opaque white. I can't seem to get it out of there. If I wet the surface with water the white goes away and it looks fine, though not yet level. but as soon as it dries the white comes back. It's really bad in one spot, the bass side upper bout and around the soundhole affecting the rosette area as well, but a little bit in other areas of the guitar, while other large parts seem totally normal.
It doesn't seem to want to sand out easily, it might have go to bare wood, I don't know...
Does anyone know what may have caused this? How can I prevent it in the future and what seems the best fix?

[Bob Gramann]

Was the Zinsser shellac Sealcoat? That's the only one that is dewaxed. I'm wondering if your finish is delaminating because it won't bond to shellac with wax in it.

When I have sanding residue in pits (like unfilled pores), the vacuum cleaner usually removes it. Then, I go back and fill the pits before I try finishing again.

I usually spray 6 coats of EM6000 over two days, level sand that the 3rd day, then spray 6 more coats over the next two days. I wait at least 10 days before the final level sanding and polishing. I'm in the process of doing one now where I compressed the job into two 6 coat days. It seems to be going fine, but I won't know for sure for at least 9 more days. I have completed many dozen guitars using Em6000 (and its precursers PSL and USL). I use dewaxed shellac flakes with Everclear alcohol for the base coats. I have never seen what you are showing. The shellac is likely to seed when sanding. The EM6000 will form seeds if it is sanded too soon or vigorously enough that it gets hot.

Looking again at your photos, it appears that your lacquer has crazed. That could be from the aforementioned waxed shellac or from shooting too many coats too fast or from changing temperature issues. If it really is crazing, you will need to go back to the beginning (and you will need to worry about the other two guitars that haven't shown problems yet). Good luck.

Overall, I like the EM6000. I think it is worth the time and trouble to dial it in. You get a pretty reasonable finish without toxic fumes (you still need a respirator when you spray). And, it will burn into itself when you do repairs.

I did try the Target high build lacquer. With that, I had crazing problems. That was the end of that experiment.

[Ryan Mazzocco]

Thanks Bob. I just used the regular zinsser shellac. That's what Joe used so I figured it would be okay. I do know that there was an uneven build up of the shellac in the offending area due to a sag in the first coat. I sanded it down but there was still a little bit thicker in that spot. I didn't think it would be a problem since I was going to sand it all again anyway after many coats. but perhaps it is a problem. Like I say, about 75% of the guitar is problem free.
I did shoot more coats in a less amount of time than you did, but still well within the parameters set forth in the directions on the can. And the temperature was kept relatively constant as far as I can recall.
but maybe I should look into getting the wax free shellac and adjusting my schedule.

[Bob Gramann]

I apply the shellac with a pad as in french polish. Generally, I shellac and reshellac as necessary while I'm preparing the surface. In the end, my shellac coat is very thin. The wax or the shellac thickness or both could have caused the crazing. Good luck.

[Barry Daniels]

Were the 10 coats applied in one day? If so, that is too much, too quick. And the shellac needs to be wax free.

[Ryan Mazzocco]

I just got off the phone with Jeff from target coatings and he confirmed that the waxy shellac is the problem. I don't know why Joe has never had this problem but he won't be using it anymore either. In fact Jeff said the 6000 will go on the bare wood just fine with no sealer. Also, no need to start over. The damage has already been done and Since the white disappears with lacquer over it I can just keep adding coats and level sanding until done.
Thanks everyone

[Bob Gramann]

EM 6000 does go on bare wood with no adhesion issues, but it will raise the grain. You can sand back to level after a couple of coats and then go on, but I find the shellac is convenient for many reasons.

[Ryan Mazzocco]

That makes sense, since it's water... of course it would raise the grain. I'd rather not mess with that too.

[Randy Roberts]

I have no experience with EM6000, but would like to address the shellac.

The Zinsser shellac is not dewaxed.
The Zinsser SealCoat sanding sealer is supposed to be dewaxed, and has often been suggested on a number of forums as a convenient replacement for making your own shellac.

As I've been tied up for a while with furniture projects, and going through shellac more than usual, I decided I'd go to the SealCoat for those.

Just to be on the safe side I filtered it through paper coffee filters just in case there might still be some wax present.
I happened to notice after a bottle had sat on the shelf for 3 months undisturbed that there was the characteristic whitish accumulation at the bottom of the glass bottle typical of wax. So.

I'll only be using made-it-myself shellac (flakes and Everclear for me) from now on anything as important as an instrument, and I'll let it sit for a while and then decant what I use off the top in case filtering doesn't get all the wax out.

For what it's worth...

[Chuck Tweedy]

yep - its the wax.
The waterborne was pulling away over the surface (that it was not sticking to) as it dried. Created those cracks.
Not sure why anyone would every use shellac from a can when it is so easy to make from flakes - that you know the quality of.

[Randy Roberts]

It's kinda a guy thing Chuck.... can you spell L...a...z...y ?

[Eric Knapp]

yep - its the wax.
The waterborne was pulling away over the surface (that it was not sticking to) as it dried. Created those cracks.
Not sure why anyone would every use shellac from a can when it is so easy to make from flakes - that you know the quality of.

I'm sure many ask this question often, but I don't know. Where do you get the flakes and solvent? What kind of containers do you use?

And one answer to why some would use SealCoat from a can is that I have no experience and little time. I just want to try some shellac to see what it's like and to start learning. I'm not using it on a guitar or a piece of fine furniture. I'm just using it for some simple things to get going.

Thanks,

-Eric

[Steve Sawyer]

Eric - most anyplace that offers woodworking tools & supplies will have flake shellac, and in multiple colors. Woodcraft, Rockler, Peachtree, Amazon, Hartville Tool, and I wouldn't be surprised if LMI, StewMac and other lutherie suppliers don't all carry it.

Solvent can be denatured alcohol from the hardware store.

Dewaxed Garnet Shellac Flakes 1/8 Lb. Or (2 Ounce) https://www.amazon.com/dp/B00WLB0ITY/re ... qyb1QR5M77

[David King]

If the WB varnish is raising the grain you might consider wiping all the wood with a damp sponge first and sanding down that raised grain (when dry) before you apply the WB. We aren't building violins here (they don't believe in sandpaper apparently) so we can do what it takes to get it right.

[Randolph Rhett]

You can order both pre-mixed and flakes from shellacfinishes.com. The seal-Lac is regular dewaxed shellac. If you French polish, I'm a big fan of the Royal Lac for the top coats.

[Randy Roberts]

Eric,

One good way to make your own shellac was posted here years ago by Al Carruth.

I really like it because it's simple, and works.

Get your shellac flakes.
blonde or platinum blonde will probably be the most versatile for you, but it works for any shellac including buttons, etc. Proportions of flakes to alcohol is really of very little importance, you can always dilute it out with more alcohol.

Get some alcohol.
If you are in a state that you can purchase 95% Ethanol, such as Everclear, I'd recommend using that. Not the cheapest way to go, but it will flash off faster than weaker strength alcohols that are diluted with water, and, important to me at least, you aren't inhaling the toxic denaturants like methanol that are in denatured alcohol. (Ages ago I could get 95% Ethanol by writing a prescription for it, and the pharmacy could get it by the gallon at about 3 dollars a gallon because there is an exemption to the usual taxation and control mechanism for medical uses. In this day and age of big chain pharmacy, you can't find a pharmacist that has a clue what you're talking about. They just point you to the liquor section.)

Steal a pair of nylons or panty hose from your significant other.
put the shellac flakes, buttons, whatever, in the foot of the stocking, tie a knot in it, and suspend the pouch of shellac in the alcohol. A wide mouth jar with a screw lid will let you do this the easiest, but, if you are patient, you can pour a little of the alcohol out of the Everclear bottle to make room, stick the foot of the nylon down into the bottle neck, and funnel the flakes down into the stocking. It helps, (a lot) if your first grind the flakes up in a coffee bean grinder to let them flow down the funnel. Screw the cap back on, with the stocking suspended at the top of the jar or bottle.

The dissolved shellac will flow downward, creating a current in the jar that brings the weaker strength alcohol up to the flakes. Once the flakes are all dissolved, any debris, sticks, and bug butts in the flakes are trapped in the stocking and you can just lift it out.

You can then pour the shellac through a paper coffee filter to filter out any wax, or just let the bottle sit for a while and the wax will settle to the bottom of the bottle, and you can decant off the clear upper portion to use.

[Steve Sawyer]

You can then pour the shellac through a paper coffee filter to filter out any wax, or just let the bottle sit for a while and the wax will settle to the bottom of the bottle, and you can decant off the clear upper portion to use.

I didn't know that wax was an issue when making shellac from flakes. At least, I've never given it a thought when mixing it up for use on furniture. I always thought that being de-waxed was one of the advantages of mixing up your own from flakes.

[Peter Wilcox]

I think raw shellac from the bug contains wax. The wax has to be removed to make it "de-waxed." You can buy the flakes either with wax or de-waxed.

I get mine here: https://www.shellac.net/Shellac_ordering_list.html

[Jim McConkey]

From Peter's source (good outfit, same place I get mine):

"Wax content provides some flexibility & moisture resistance. 'Waxy' shellacs are a good choice when the finish will be shellac only."

"Use a Dewaxed shellac for a universal sealer / primer and as a transitional coating between dissimilar finishes. Use a Dewaxed Shellac when the topcoat, for extra water & alcohol resistance, will be a varnish, lacquer or urethane."

[Randy Roberts]

One point I was trying to make was to not assume anything, whether Zinsser seal coat, or flakes "de-waxed" or not .

Trusting that someone else did a thorough job for you is one way of asking for trouble.

As a dead president once said "trust, but verify"