Official Luthiers Forum!

Welcome to the forum, Vijay!

Never boring to any of us who are trying or using Royal-Lac. Great product, and very easy to use if you are not spraying.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Welcome Vijay!

I have a question.

How is it for touch ups and repairs? Does it burn in to previous layers to leave no witness lines?

Thank you for the warm welcome, Waddy, and thank you for the praise for Royal-Lac. Have you tried spraying Royal-Lac as described by Tim?


In response to a question from Ed Bond:

I'll post what Tim McKnight had to say. His observations are accurate.

Don Williams wrote:
I'm also curious about burn-in, and how difficult it may be to repair, as well as how tough it is in resisting body chemistry and scratches, etc. When I think shellac, I think " FRAGILE ! ".

Tim McKnight wrote:
It will burn in if you catch it within 2-3 weeks. After a month you will have to abrade it to get good adhesion. I've not seen any witness marks after repairs.

"Its very abrasion resistant after a month. You can scratch it with your fingernails and it won't leave a mark. However, you can DENT the wood under the finish so this tells me the finish is flexible.

Adhesion is excellent. Michael Bashkin and I both did cross hatch adhesion tests and neither of us could get it to delaminate or flake off."

Vijay: A bit of explanation as to why it is repairable in the first 2-3 weeks; Royal-Lac is not catalyzed, hence it cross links over time as the solvents evaporate. Therefore during this time period, it is very much like a thermoplastic finish. Quite readily reactivated with a new coat. After solvents have evaporated, it sets up like a thermoset finish.

Thanks, guess I missed that tidbit...

Tim,

This is great info, but for #5, you didn't say for how many days you apply the 4 coats per day...
Is this for one day (4 coats) or two days (8 coats), or even more days?

I'm currently laying down a few barrier coats of shellac now and will begin spraying Royal Lac in the next day or so.
In spite of aggressive pore filling, I'm having issues with the shellac sinking into the pores, as if the pore fill (CA Glue) is also shrinking, so I've had to go a bit thicker with the barrier coats.

Things I've learned in the process:

1. Brushing shellac is problematic, even with a really good brush.
2. I suck at brushing shellac on the surface, and then being able to get the inconsistent thickness of shellac sanded level!
3. No matter how hard you try, any tiny impression in shellac will not fill with more shellac. The shellac simply pulls away from the tiny divot.
4. Pore filling is a pain in the butt.

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"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."

Hi Don,
Patient and accurate pore filling is KEY. Use epoxy and not CA. Use as many coats of epoxy as needed to get a perfectly FLAT surface BEFORE applying RL. I follow my schedule as outlined above and copied again below with NO additional coats between steps 5 & 6:

5. Spray 4 coats of Royal-Lac per day at 3-4 hour intervals and let dry for 2 days.
6. Spray 4 coats again in a day and let it cure for 1 week.
7. Level (block) sand with 320 grit leaving a very thin film of Royal-Lac on the surface.
8. Spray 4 coats at 2 hour intervals and let dry for 10 days

(12 total coats)

RL won't fill pores in and of itself because its too thin and shrinks into them compounding the problem. If you start with a perfectly flat base and then build the RL on top of that it will make your life a lot easier.

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tim...
http://www.mcknightguitars.com

Ah... thanks Tim. Your wording in #5 led me to believe that you shot four coats per day for more than one day. I guess you meant "Spray four coats of Royal Lac on Day 1 and let dry for two days". That makes sense now.

I think that mostly I'm experiencing small pits from brushing, and then not sanding flat enough before brushing or spraying more shellac. (This is sealer, not RL) I have to be more aggressive with my sanding I think. One thing is for certain... you can't drop-fill tiny pits in shellac. It won't go in there. You almost have to sand it all back and re-apply your base coats if you get them.

Do you feel that the PSA discs are better than velcro discs for this purpose? I'm thinking I may buy a flat PSA base for my electric RO sander. If I do, should I be using a firm or soft base?

Thanks!

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"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."

Don,

I use H&L on a firm sponge OEM pad on my ROs. I've never had luck with PSA discs. Over time they go air born across the shop like a ninja throwing a razor edged Frisbee.

You can drop fill gaps or voids using a plastic tooth pick, dipped in RL, then dab RL into the small pores or pits using the point of the tooth pick.

I suspect you may be applying it too thick and the small pores or pits (solvent pops) are left as the solvent trapped under the thick layer of finish escapes on the surface. Thinner is better.

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tim...
http://www.mcknightguitars.com

Tim, I have yet to apply any RL, as I've been dealing with the shellac sealer, which I brushed on instead of spraying.
I was going to start yesterday, but wasn't quite ready, and today I've been dealing with a split cast iron waste pipe that's leaking sewer gases into the basement shop. ICK.
I decided to try my luck with the Klingspor sanding discs on my Bosch RO sander, and ordered the H&L no-holes version. Hopefully, they will speed things up a bit. Too bad, I actually find wet sanding by hand somewhat relaxing. Except that it kills my arm after a few seconds. Getting old!

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"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."

Eat more spinach PopEye!

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tim...
http://www.mcknightguitars.com

Spinach? Gross.

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"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 have experienced some serious cracking problems with spraying Royal Lac. I have notified Vijay and I'm confident we can find a solution so please don't think I am bad mouthing this product. Until we find the root cause of this failure please discontinue spraying RL. The problem is localized ONLY on softwood tops. We have not had any problems with the finish cracking on hardwood back and sides so it has to be related to how the softwood tops move under temperature swings.

It could be related to the spraying process since we have not had any reports of RL cracking with brush or hand applications.

Its worth mentioning that I subjected these guitars to ~2 months of cold storage inside guitar cases. The temperatures dropped into the teens. This was a test to see how the finish would fare. Before using RL I had conducted some sample tests using my deep freezer but I never saw any hint of cold checking. I slowly brought the cases up to 65*F over the course of ~6 hours before opening the cases. The guitars were up to temperature and were not cold when I opened the cases so it can't be from temperature shock cold checking. The cracks run along and cross the grain and run randomly all over four tops (Adi, Englemann, Sitka and Redwood).

I'll update this thread as I learn more. Until then I have 4 necks and bridges to remove

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tim...
http://www.mcknightguitars.com

Great timing - I just sprayed the first coat on my BRW OM before your post and PM !

I strongly suspect that
a) the cracks happened when frozen prior to warming them back up or when they cycled during that time in the case, or
b) the mix needs some sort of plasticizer, or
c) intentionally keeping instruments in sub-freezing conditions is simply not a good idea! <G>

I'm going to continue the process, and see how things turn out, but I may pad the finish onto the top.
It doesn't make sense to me that the method of application would make a difference in the finish cracking or not cracking.
This has to be temperature related, or perhaps the solids content had something to do with it. Vijay will figure it out, I'm sure.

Best of luck with the neck & bridge removal / refinishing Tim...

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"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."

BTW,
I really like the look of the first coat. The color and transparency are everything I'd hoped for.
I was a bit taken back by the color of the finish in the can, but felt it was just the right thing!
It was very clear, with a strong red hue to it - which won't break my heart any going on top of the brick-red Brazilian.

Thanks Tim!

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"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."

Bummer man...

Tim, just curious: How stable was your cold storage for humidity? Could it have been hum swings that caused the cracking?
Mike

Tim and I have exchanged emails about the problem. By looking at the photographs that he sent, I noticed that all cracks were along the grain. Please correct me if I am wrong, Tim.
There are two ways a finish will crack. 1) If the finish fails due to temperature or humidity or 2) if the wood movement is excessive.
For scenario 1) The cracks will always be random and without any pattern. It will look like a river as it drains into the ocean creating small deltas. This is caused when during the curing process, the glass transition temperature (Tg) of the finish is pushed up speedily into the glassy realm of the polymer by use of a catalyst or temperature. The goal of every formulation is to push the Tg up in a controlled manner to dry fast enough during a short period of time and then retard it. The fact is that Tg is continuously moving up slowly with time. With pure shellac it moves rather slowly and with synthetic finishes, faster. Hence once shellac reaches the glassy state after 50++ years it starts to crack. Synthetic finishes will crack much faster.
Tim's photographs do not show this type of cracking. Hence I can confidently say that it is not a finish failure.
Scenario 2) Long cracks along the grain are seen when there is excessive wood movement due to temperature and humidity. Two areas of concern - 1) if the finish is not flexible, it will crack. 2) If the finish has partially cured and is still in the curing stage and the wood is subjected to one extreme temperature, it will crack. I believe that in Tim's case, it is the latter. Due to higher solids content, Royal-Lac needed more time to cure and it would have been fine if it had cured at room temperature (finish will be in equilibrium) and then subjected to cold temperature in the loft. But unfortunately it was still in the last leg of the curing stage and was subjected to cold. Due to the cold, the wood shrunk and so did the finish. When seen at a molecular level, the molecules got packed together tighter minus their chains. As the temperature increased, the finish could not keep up with the expansion since it was resting at one extreme end of the equilibrium scale.
Royal-Lac does not have any plasticizers and there is no need for any as long as it is first cured and then subjected to temperature and humidity. I am continually testing and so far I have not had any failures. My latest test is one where I have a test piece out in the open since first week of October. We have had rain, Santa Anna winds, cold and hot temps over the last 6 months now. No failure.
Tim's method of spraying is not the issue here. His technique allows him to atomize Royal-Lac effectively so that it dries faster. In this case he is using atomization or crudely put - evaporation of the solvent in driving up the Tg.
To sum it up, I can say that when using higher solids content Royal-Lac, reduce number of coats per day and give more time for cure.
Please feel free to email me and ask questions anytime. I am willing to get into greater details if need be.
Many thanks to Tim for his unending support. I wish I can help him fix the four instruments!
Vijay

Thanks to both Tim and Vijay for keeping us abreast of the changes and expectations. So far, I have sprayed two coats today, and will do one more coat later this evening and let it sit for a few days before applying more per Vijay's advice.
I will try to report back with my findings and post some pictures along the way if I am brave enough to post them here.
It's my first instrument in several years, so perhaps not as perfect as I would like.

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"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'm also very impressed with Vijay. Not from a technical stand-point, but from a service stand-point. He was very gracious with me over the phone a few days ago, and my order arrived nicely packed today. I can't wait to start working with the products.

Tim, Did you seal the soundboards with epoxy as well?

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Stay with the happy people.
--Reynolds Large

I have been testing Royal Lac for Vijay for over a year now. I have done many sample boards and the maple guitar you see in the video I did for him. All look just fine and have not had any issues as mentioned by Tim. It is asking a lot of any finish to be able to go from sub zero temps and back to higher temps without affecting the finish. They would probably also have major issues with the instrument itself. If some one were to contact me saying that they had wood movement sufficient enough to cause finish damage it would not be covered under my warranty.

French polish finishing is a large part of my business.

Even traditional French polish finishes are not immune to crazing. In my career, I've had one guitar with crazing over much of the top. I've seen a handful of tops with some small areas of crazing. I think these problems were related to rate of application (building up too fast).

There is a Mil-Spec for crazing in lacquer finishes. It involves spraying lacquer on a metal plate, and subjecting it to temperature extremes. Maybe that could be a starting point for evaluating new guitar finishes.

I have no experience with "Royal Lac". I use Vijay's shellac flakes dissolved in SDA 23A.

I bought shellac from a variety of suppliers, and dealt with a variety of problems, before settling on Vijay's company. I have always been pleased with his products, and with his customer service.

I think we all know this...
I can't speak for Tim, but I think he was doing this as part of his testing because he wanted to have a finish that could withstand those kinds of conditions so that his customers didn't have to worry about the occasional lapse of memory or judgement.

I feel terrible for him that he now has to re-do those instruments...

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"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."

Tim has my sympathy too - I just stripped the lacquer off of two and it's a suck job for sure.

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Steve Smith
"Music is what feelings sound like"

Vijay and I have been corresponding about Tim's experience and per Vijay's request I have put my sample boards into the freezer to see if I can reproduce the issue. I put a rosewood board and a spruce board into the freezer today for six hours. The spruce is just a chunk of bracewood but the rosewood is the thickness I would use for a back. Both of them look fine after freezing and coming back to room temperature. See attached pics. These boards were done about a year ago though. Also, the spruce board never had the finished leveled and buffed. It is as I applied it. The rosewood sample was leveled and buffed.