View Full Version : Spray shellac first coat
I'm nearing completion on my #1. Things are looking good. I've opted for alchol dyes and a french polish finish. I've been working a bit with practice pieces and one thing I've noticed is that after I rub and spray on my sunburst, the first application of shellac rubs out a bit of the stain (both alcohol based). After that initial layer is down, things are fine as the stain is sealed in. However, especially on the spruce (pine for my practice bits) this leaves noticable blotchiness and streaking that isn't there after the staining is complete.
Is there any reason that I shouldn't thin down my shellac and spray the initial coat directly on the instrument to accomplish this sealing? Will this somehow hinder the ultimate adhesion of the finish to the wood? Thanks in advance for your thoughts.
Dudenbostel (http://www.diynetwork.com/diy/hb_musical_instruments/article/0,2033,DIY_13881_2886513,00.html) does it.
I've done it on the last 2 instruments I made and it almost eliminated the 'smearing' issue. I used Bullseye can shellac, but putting a thinned down cut in your spray gun (along with a leveling agent/retarder) shouldn't be a problem and will probably allow you to get a thinner/more uniform coat than brushed.
I do it all the time.
Be sure to spray a very light coat. The thinned shellac will run "like a freight train" if you spray too heavy, taking your stain with it leaving dark sag lines.
The only theoretical down side to it would be that in the French polish technique, you are really forcing the shellac into the wood and therefore the adhesion may be better with the padded on shellac. However as you're doing this over the dyed wood, it would tend to smear the colors.
I sometimes spray a thin coat of shellac inside my acoustic guitars, doing the backs and sides. Works fine if not overdone.
I spray a thin coat of shellac after staining also. It seals the color and provides protection for the color while I scrape the binding.
I then varnish, level and then french polish, it seems to me it would take a long time to build up to a final thickness using just french polish.
I sometimes use vinyl sealer. A light coat. Then as far as I've found you can do as you please over it. Out of curiousity, who sunburst dyes the wood (whatever way), seals with shellac, scrapes the binding, and then continues with shellac, french polish, with no barrier coat in between and doesn't expect color bleeding problems? Must be some very light fast drying undercoats if applied by hand. I believe even Gibson used varnish over the dye before FP. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif??
I do this on most everything stained. I use vinyl sealer on bare wood with lacquer. Be careful with the spray can shellac. It can give you some LARGE drops that will leave a spot in the color. Very light coats!! Even the layers after can cut through down to the color layer if you are not careful. Alcohol soluable materials will re-dissolve easily. Why not some color in the shellac if you spray with a gun? Could add a little depth to the appearance too.
One approach to this "problem" is to use water based dyes. They are supposed to be more light fast than the solvent based ones, and the alcohol won't dissolve them near as much as the solvent based dyes.
But with water based stains the grain may rise if the wood wasn't prepared properly.
If the wood is stained just on the very surface (e.g. airbrushed alcohol based stain that dries right on the top of the fibers) you can get the "washed" spots, but is the stain is applied by hand, the color is deep in the wood and the spots are less likely.
I use airbrush for applying shellac and it works great both on sprayed and rubbed stain.
I use hand rubbed water based dyes AND spray shellac as a base, but I also sand to 220 grit, then raise/wack the grain with 320 grit about 4 times.
Most say 320 is overkill, but I find that it helps, especially on the spruce, to get more even staining. I always worried that alcohol based stains would smear easily/easier than water based. Heck with water based dyes you can almost wipe your binding down with acetone instead of scraping and get away with it (almost, but not quite)
I also use a bit of colored shellac brushed with a small, flat, artists brush to darken/even out the vignette, the points, etc.
This will sound completely counter-intuitive, but I like to seal color with McFaddens lacquer no matter what I'm going to use for the final coats.
Shellac will much more likely cause bleed unless you really get that thin coat on. Heavy laquer will bleed it too, but sets up so much more quickly it's usually not a problem. THEN I use a shellac coat if I'm going the varnish direction because it's so compatable with any finish medium.
Dale, the vinyl sealer is actually much the same I think, lacquer with vinyl mixed in.
I have been useing hide glue to seal in the stain.It's been used for centuries on fiddles and it works great.It leaves the grain on the spruce more sparkly and seals better than anything.It's easy to apply,peels off the binding with a fingernail, and you end up putting on a lot less varnish to do the sealing. With each coat of varnish the previous coats will solve a little and they settle together as one coat making a long process of filling. Hide glue does it in one coat and isn't solved by the next varnish coats. Try it outand report back here. I'd like to hear others experiences.I first did it on a blonde mando because I was afraid of haveing two different woods with two different absorbtion rates. The hide glue made the different woods work like one wood because of the common sealer. It works great.
Jim, you may be right. I should look on the can! But it smells like lacquer. I also use McFaddens as a sealer, and like you, if I'm going to varnish I use shellac over the lacquer because everything seems to bond well with it.
I have been useing hide glue to seal in the stain.It's been used for centuries
I LIKE THAT IDEA. Will have to try that out next time. And now that you mention it, that may be what's under the varnish on my Loar. It is certainly a thin layer of something hard and shiny.
Do I understand correctlt that you are putting hide glue on after staining? I have heard of doing that before staining but not after. Does the cut matter much? Would you mind explaining your process a little more?
But if you use hide glue, wouldn't the instrument smell like hooves and snouts?
I stain it like usual, then apply a thinish coat of freshly made hide glue with a hogs hair brush.The staining process kinda burnishes the wood and the grain doesn't raise all that much. It has worked real nicely on my last several mandos. Also I think there is something acoustical happening too. My stuff has a more clear sound,maybe brighter. Not sure. Like I said it's been used in the fiddle world for about 400 years. I'll try to include a tight pic of my latest top to get some feedback. I think the effects are good, visually and acoustically.
I make mine smell like Jello,strawberry is my favorite!
I like the smell of lac bug excrement...
Darryl, you can test if it is hide glue by touching it with moist finger. If it's hide glue it would feel sticky and would wear off rather easily. And hide glue wouldn't be as shiny, IMO.
Shiny ?. Do you mean under varnish?I think hide glue under varnish looks like it sparkles some. Also, old hide glue can take forever to solve and get tacky.I'm including a pic I took at Loar fest that got me thinking. This looks like a hide glue sealer to me. The way the varnish darkens and the way it has peeled off the wood reminds me a great deal of very old German violin work I've seen a million times. The Germans almost always sealed with hide glue.
Shiny ?. Do you mean under varnish?
I do not think any of it shows now, but will check to see for photo op. When I got the mando, perspiration had deteriorated the varnish on the back in the armpit area. Maybe 3/4" x 3" at the edge. There was a thin, hard, shiny coat of something directly under the varnish. That coat was not affected. The varnish went from perfect to soft and sticky as you approached the affected area and then to non-existant revealing that undercoat. I simply french polished it and you cannot tell anymore.
All I can with any certainty is that there are two different material on it. Something over the stain and then varnish
Darryl, it got sticky? that's interesting. Thanks
Maybe it was from the armpit.
I found this site very informative for varnish technique. Their current preference is to use epoxy over the entire instrument. Hide glue sounds more traditional!
In the violin world this coat of something under the varnish would be called a "ground", and there are many, many formulae for them.
Darryl, it got sticky? that's interesting. Thanks
maybe not exactly sticky, but soft and "fingernail-able"
would ANYONE coat their mandolin in EPOXY!!!!!? I hate the stuff and don't use it on anything.I'd bet my life that Loar didn't use much either.
Rick was it you that posted the mineral ground stuff a year or so ago?
I like the hide glue wash idea but how heavy a cut do you use? And how do you get it to be clear?
make i thin sollution, like you would for sizing....maybe milk thickness. just brush it on..it goes on clear.let it dry for 1-2 hours, sand it(400-600 grit) and start varnishing.
Not me on the mineral sizing, but if you go a-Googling in the violin stratosphere for something like "varnish ground", you'll find more than you want to know from some very opinionated people.
My Loar has just about every kind of wear spots on it you could imagine. It is all original finish and appears to have never been frenched since new.
# On the top where your arm would rub it is worn down to the wood. In that area the wood is shinny like the wood was sealed and still is sealed with something. Perhaps hide glue like mentioned. It is very evident that the stain did not penitrate into the wood. On the edges of this wear area, a somewhat sharp line has been created from finish to no finish.
# On the back of the mando the french polish layer is virtualy gone in most areas leaving the oil varnish exposed. In one area it looks as if the varnish was wiped on as opposed to being brushed on. The texture of the varnish finish there is smooth but more like it was raged on with long strokes. Other areas of the back where the varnish is thicker, it appears to have a more polished look. There isn't any real bare spots on the back so I cannot tell if the stain penitrated into the wood but my gut feeling is it did in order to get the grain contrast.
The neck looks yet a little different. I appears like some of the base color stains penitrated the wood yet the darker stain is laying on top of a sealed surface.
#In my opinion, Not just one method was used to finish the whole instrument.
And I'll go further to say that as with every maker from Amati on down, the finish process changes all the time. There's not one builder who can say they've never tried anything but what they're useing now.It's kinda hard to say what was used with just a small sample. Makes it impossible to say any one thing for certain, and that makes all this even more fun I think.
There was a thin, hard, shiny coat of something directly under the varnish. That coat was not affected. The varnish went from perfect to soft and sticky as you approached the affected area and then to non-existant revealing that undercoat. I simply french polished it and you cannot tell anymore.
Darryl, could be the french polish layer (often pretty thick on Loars) that got soft. The waxe shellac can become sticky with perspiration. Shellac will dissolve in bases and perspiration contains some urea, which also turns the wood yellow after prolonged contact. The shiny layer can be just the oil varnish.
On the subject of violins most luthiers claim there is something under the varnish of Strads, but great many of them have tons of polish (shellac, propolis etc...) on them, so it's hard to tell if there was ANY mysterious ground used. Some of the micro scans show the layers, but what they describe as ground could be as well the original varnish under all the polishes.
Thirdly, I like the idea of hide glue as a sealer. But you should consider that hide glue of twenties wasn't the water clear stuff most of you, guys, use. It was caramel colored, often not very clear. I have similar hide glue made witout the microfiltration and it leaves yellow colored coat on the wood. What I like is that the grain on Loars is generally not showing like on modern mandolins. Could be any or all of the next three reasons:
a) cut of the wood
b) colors used were not perfectly clear and didn't penetrate the wood deeply
c) sealer under/over colors that wasn't perfectly clear.
Hide glue or gelatin was one of the favorite sealers under or over the colors during the era.
HOGO, that could be, but I really cannot tell.
FWIW, Paganoni uses epoxy to seal coat his prior to varnish. The top finish on most of the earlier ones is epoxy only, as his only varnished the sides and back. I varnished my no. 29 top right after I got it
It very complex, but there is something underneith these great violins.Most of them anyway.On really bashed up instruemnts it is hard to say what is there but on pure instruments it very clear to see a clear layer under the colored layer that the colored layer has a hard time adhering to.That is why they develop those beautiful wear patterens.Even on lesser violins (Testore, Grancino, etc) there is something under the colored layers most of the time.The ground to me is what goes on the wood first, then there is a layer that comes between the ground and the color. It may just be polish(still talking violins) but something is there for sure, may be accidental or purposeful who knows.In the case of mandos I think it's a fine idea to borrow something from the violin world.And like I said earlier, I'm sure that I'll change what I'm doing soon enough for no real reason other than to try something else.
Not long ago I had a Loar in for repair that had previous water damage from many years ago. If it had hide glue under the finish there would have been no finish left. The finish that is on the instrument looks to me to be original and pretty durable. There are a few very small areas where bare wood is exposed, but the surrounding finish is evenly worn to feather out at the bare spots and it is polished from wear.
I have seen a couple violins that had finish just flaking off. My suspicion is that they had hide glue as an undercoat to the finish and they got damp. Hide glue will always take up water if it is available, and when it does it swells up several times it's dry state.
Michael you're right about all that. If you put plaster of paris or chalk or ground silica into the hide glue it will change it some chemically. There are a lot of additives you can use that will not keep hide glue permanent but will help it adhere better and last longer.I know the plaster idea sounds crazy but it works well and doesn't effect the look of varnish over the top. It is a little cloudy in the jar but goes on almost perfectly clear. I'm not saying that Loar did this, there where however a few German violin makers working in the Gibson factory at some point and have wondered what amount of their experiences varnishing large quantities of instruments stayed in use. The Germans loved what they call "ising glass" or hide glue and silicates (ground glass). Again, not saying it was used by Loar but it works and I think it makes more sense than drowning an instrument in epoxy.
I spray a thin thin coat of lacquer first then use shellac,never a bleeding problem.
PS: I like the smell of Lac bug goo too, unfortunatly bugs do too. While coating outdoors I have had little winged buddies fly into the lac and flap thier wings and really **** me off! #Shellac kinda smells like honey, may work well for diareah, better check with doctor first, could cause a "compaction in your lower fraction" http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif