Hammered Dulcimer design, construction, and unrelated stuff

Sunday, December 23, 2012

Spraying Shellac Revisited

I have been spraying shellac in production finishing of our hammered dulcimers for a year now, and have come up with a few more tricks, so thought I'd update.  Read the former post on the same topic, this is additional material to that.

I have found that shellac sprays best if it is mixed at an EXACT one pound cut.  This is pretty easy to do.  I have a jar that I dissolve the flakes in that is something less than one gallon, so just dump the flakes in, fill with alcohol, and stir several times the first day.  If I stir well a couple times within the first hour, the flakes will all be dissolved by the next day.  Then I filter the mix into a gallon jug, and top off with alcohol to get the right mix.  This is probably a little stronger than a one pound cut, but works best for me.

Jugs:  glass is best.  Milk jugs work, but are thin, and the shellac can actually find a weak spot, and eat through, and leak.  But you won't lose much, because the shellac dries, and is self healing.  I found a much heavier plastic jug that vinegar came in, and it has been working very well.

Since I had sprayed lacquer for so long, it took me quite a while to get the feel for the shellac.  I was putting it on too heavy.  So, one pound cut, spray light, and move fast.  Shellac goes on different than lacquer, it does not need to wet and flow out, so you wind up moving much faster than you'd think.  I am using about half the material I was, and getting a much better finish.  The surface may look a little pebbly, but give it a minute, and it will settle down, and gloss.  Go especially light on the first couple coats, which are your seal coats.  Much less grain raising that way.

Color:  I have gone to using just the Blond flakes that I still get from shellcshack.com.  They give just a little warm glow to the finish.  I no longer mix colors, but this is still a good trick for special finishes.  But production finishing, just the Blond.

Gun cleaning:  I clean after each time I spray, never leaving shellac sitting in the gun.  By cleaning, I mean, pour the remaining material back in the jug.  Put a little straight alcohol in the gun, shake it to get the alcohol all through the cup, then spray a little of the alcohol.  Pour the remaining alcohol into a separate container that I label "Gun Rinse".  Then pour a little more fresh alcohol in the cup, shake, then spray.  You can let the gun sit as long as you like now.  When getting ready to spray again, pour the alcohol in the cup into the gun rinse can.  The gun rinse alcohol can be used in mixing up the next batch of flakes, so you don't waste any of it.  It is a good idea to take your gun apart a couple times a year, and soak and thoroughly clean all the parts.

Shellac is harder, and more durable than lacquer.  I have switched to it completely.  I don't spray lacquer at all now.  So much better!  It is also more beautiful than lacquer.  I still use the Minwax Wipe On Poly as a sealer, as described in the former post.  It works great, and helps the shellac build faster.  I just wipe it on straight, and let sit overnight.  Then scuff lightly with 220 grit paper on a sanding block. For scuffing in between coats of shellac, I have found 400 grit best, wrap 1/4 sheet around a rubber sanding block, and move your hand slowly and with very light pressure, basically just the weight of the block and your hand.  Don't press down.  If you do it right, the paper won't load at all, but if you move your hand too fast, or press down too much you will generate heat, and the dust will load the paper.  I have a piece of carpet on my sanding bench, so just wipe the paper on that to get the dust off.  With a smooth couple of seal coats, I don't need to do much sanding, just go over it lightly to get the dust motes off.  If there is a rough spot, I can do more sanding there to get it smooth.

Final polish:  With the much better job of laying the finish on that I have developed, I don't need to rub out.  The gloss is there, just like I want.  So for the top of the dulcimer, I just pass over it VERY lightly with a worn out piece of 400 grit paper to remove any dust motes.  You can't see that I have done this, and it doesn't affect the gloss at all.  For the back and sides, I still love the feel and look of wax, so I sand a little better, then wax.  I probably wouldn't need to wax, just go over the whole dulcimer lightly with the worn out 400 grit.  I just really like the feel of the wax.  These are by far the best finishes I have done in over 20 years.

I have gotten good enough with my move fast, spray light technique that I have been able to drop the use of the bed of nails on the turntable, and go back to suspending the hammered dulcimer bodies from a string hanging from the ceiling of my spray room.  I worked this way for 20 years spraying lacquer, and it is much faster.  I can spray all around the body at once.  I do six at a time.  To do the whole finish on six dulcimer bodies used to require a little less than a gallon of lacquer mix.  Two quarts of sealer mix, and 2 quarts of semigloss mix.  With my move fast, spray light technique, I am down to just over a quart of 1 pound cut shellac to do the same job, and the finish is better.  So about 1/3 of the material, and shellac works out to be cheaper than lacquer.

So; shellac is harder, more durable, and better looking than lacquer.  It takes a little longer to apply, but the results are worth it.  I am using a lot less material than I would lacquer, and I believe this has translated into cheaper.  Shellac is safer, I don't need to keep 5 gallon buckets of hazardous materials around.  It is safer for the environment, safer for me.  It is also safer for customers since there are no chemical sensitivity issues.  It is better for the economy since I am not supporting a large chemical company, just small businesses like shellacshack.com, and the guys in India that produce the flakes.  It is a win/win/win/win situation.  What isn't to like here?

In going over these posts I realize I have left out something big.  Spraying shellac can be dangerous.  An aerosol mixture of alcohol is explosive.  Don't try it in your basement.  You either need to be outside in the open air, or you need explosion proof facilities inside.  There are two types: A spray booth, and a spray room.  A spray booth is a 3 sided box with a very large explosion proof exhaust fan in the back, and over spray arrestors to filter the air before it goes through the fan.  Large spray booths are where body shops paint your car, and they require a LOT of air to keep any of the aerosol spray mix from escaping into the shop.  A spray room uses a much smaller fan, but takes up a large foot print in your shop.  To be up to code, a spray room needs to be covered on the inside with 5/8" drywall, the lights need to be explosion proof, have an explosion proof fan to exhaust outside, and all electric switches need to be on the outside of the room.  This is what I have, and with the amount of spraying I do, it has been one of my best investments.  

Wednesday, May 2, 2012

Spraying Shellac

It was impossible to find any info on this on the net, and since I have been working on it very hard for several months, and have it figured out, thought I'd post my experience. I have been spraying lacquer on the hammered dulcimers that we build now for over 20 years. Figure I have finished at least 5,000 of them myself, so am pretty good with a spray gun. But lacquer is toxic, and even though I protect myself very well with a respirator, and complete HAZMAT suit, I still get a small dose. So I had been looking around for several years for a healthier alternative. Water based lacquer isn't feasible in my shop because it is temperature sensitive, and I can't maintain the warm environment year round. It is also a product of chemical companies, and works much the same as solvent based lacquers. But I finally found the right alternative... Shellac!

 Shellac is old fashioned. It is what was used before lacquers came along over 100 years ago. It has some advantages over lacquer, but it is different, so needs to be handled differently. But once you learn how it works, I think you'll like it as much as I do. One advantage is that it is totally nontoxic. Shellac is a natural material, produced by a bug that lives in India and Thailand. It is harvested by hand, and much of the processing is done by hand. It is edible, and you have eaten lots of it like in coatings on candy and medicine.

Shellac comes as flakes that you dissolve in denatured alcohol. I get my flakes from www.shellacshack.com. They come by the pound in several different colors and grades. Denatured alcohol is available at home centers, hardware stores, and paint stores by the gallon. Not all brands are the same, I use the Sunnyside brand, and it works well. There is lots of stuff on the net about applying shellac by brush or pad, but none about spraying except to say that it is possible. So I had to do the experimenting myself. This is how it is done.

Use what is called a one pound cut. Which means dissolving one pound of shellac flakes in one gallon of alcohol. It takes a while for the flakes to totally dissolve. Just put them in the alcohol, and stir several times a day, and they will eventually completely dissolve. Use a glass jar for dissolving the flakes.  It may take several days, be patient. Once they are dissolved, I filter the solution through a paint strainer into a clean plastic milk jug. Don't try to store shellac solution in metal containers, it is corrosive.

Shellac at a one pound cut can be sprayed through any gun that will spray lacquer. I am still using lacquer for some things, so I have a separate gun reserved for the shellac since the solvents are totally incompatible. Keep your gun clean! You want to make sure all the shellac solution is out of there before the end of the day. You can leave some alcohol in it, but no shellac.

Shellac can be sprayed directly on bare wood, but the alcohol being a polar solvent will raise the grain of some woods. Most of mine is sprayed on birch ply, so I need to seal the wood before spraying. I have found Minwax Wipe on Poly to be ideal for this. It can be used straight, or cut 50% with mineral spirits, either way. Wipe it on like it was stain, wipe the excess off, and let dry over night, and it is ready to go first thing in the morning. Shellac will stick to anything, so there are no compatibility issues.

One big issue here... GET RID OF THOSE OILY RAGS IMMEDIATELY. In the winter mine go straight in the wood stove. In the summer, they get spread out on the driveway to dry. DO NOT LEAVE THEM IN YOUR SHOP, they can spontaneously combust. I know a contractor in Missouri that burned their paint building down 3 times before they figured this out.

Spray the shellac thin, just like you would lacquer, but you have to be very careful if spraying it vertically. It runs and drools much easier than lacquer. So I lay my dulcimers flat on a turntable, and spray that way. It only takes a few seconds for the alcohol to gas off enough for me to turn the dulcimer over, or hang it up out of the way. I have a bed of nails on the turntable so the dulcimer is lying on the tips of the nails, not a flat surface. Standard paint room trick.

Best thing to do is 2 light coats, then let dry for an hour or so, then scuff down with 320# or 400# paper. Then another 2 light coats. The stuff will load your sandpaper so be prepared to use more than you would with lacquer. Shellac is by nature a high gloss finish. You can control the amount of gloss you get by how much you spray on. I want a satin gloss, or maybe just a little higher, so I stop at 4 coats. If you want more, scuff down again, and put on some more.

If the wood is sealed well, the shellac will build up a nice flat coat, and next day I can polish it. If it is rough, I will sand it flat with 400# paper, then rub out with 0000 steel wool, and carnuba wax. I use the Trewax brand from the hardware store. After buffing the wax, the finish has a soft matte glow, and feel that is out of this world. If the finish is fairly smooth, I will skip the steel wool, and only lightly go over the surface with a worn out piece of 400# paper to take off any dust motes that might be there. Then wax with a rag, no steel wool. This gives me the gloss that I really want, which is just enough so there is a little shine, but not glassy.

For the top of the dulcimer, since the bridges are not fastened down, I use Meguiar's #7 Glaze which is at the auto parts store. Wax is too slick, and the bridges might moved too easily. The Meguiar's seems to do the job just fine, and isn't so slick.

Color: Shellac comes in several colors depending on how refined it is. Platina is almost water white. Super blond has just a little color, you'd have to put on a lot to see it. Blond has some color, and is nice. Garnet is the old fashioned orange that you have seen on wood work in old homes everywhere. I use the dewaxed flakes. I like to mix Blond and Garnet shellacs. I mix up separate jugs of the two colors, and find a mix of 75% Blond, and 25% Garnet gives my birch ply a beautiful golden glow. I like this stuff a whole lot better than lacquer.

Top coat: If for some reason you want something else on the surface, you can use the shellac just for color coats, then top coat with anything. Shellac is the universal sealer, and anything will stick to it. I sometimes do this if I want the color, but also need the dependable semigloss of lacquer without the wax. Works fine.

So the disadvantages of shellac are that it is a little more complicated to do right, takes a little longer. I don't think it costs more, about the same as the Sherwin Williams lacquer I have been using. You also have to think ahead to have it ready when you need it. It also won't keep forever, needs to be used within 6 months of being mixed up.

But the advantages out weigh the disadvantages. I no longer need the HAZMAT suit. I do use the respirator, but as soon as the surface is dry, I can shut off the explosion proof fan in the spray room, and there is no smell at all!  No gassing off for days, and making me sick. I can spray the shellac in the morning if I want to, polish it up after lunch, and we can put the strings on the same day. No waiting for several days for the dulcimer to quit stinking. Also no worries of sending it to somebody with a chemical sensitivity, and making them sick even after we can no longer smell it. And we are not supporting large chemical companies, instead we are supporting small business both in India, and here, like Shellac Shack. And it is much better for the environment.

Saturday, January 14, 2012


I have been spraying lacquer for twenty years now. Hated it the whole time. It is nasty stuff. I have to wear a complete hazmat suit, respirator, rubber gloves, boots, and still I can't help getting a small dose. It is also bad for the environment. I can't see how I am being a good steward of the Earth by spraying these chemicals out into the air. But it is fast, and looks good.

I have been looking for an alternative for years. I looked at water borne lacquers, but they require a warm environment, and warm materials, which I can't guarantee year round. Whatever I do has to be sprayed. Brushing or wiping finishes on are too slow, requiring multiple coats and risk dust settling on them before they cure.

So last year I discovered that I could spray shellac, then when it is dry lightly sand it, then rub out with steel wool and wax. This is a very nice finish with a soft satin glow, and feel that is out of this world. We like it a lot. It is an all natural finish, completely non toxic, and totally green. Shellac is an insect resin that is collected in India and comes as flakes of various shades which are then dissolved in denatured alcohol. It can be sprayed on all in one session, unlike the lacquer which requires two. And also unlike the lacquer, it doesn't gas off (stink) for several days. The shellac is well cured within a couple hours, and can be rubbed out the same day. So we are switching all the Phoebe and Wood Thrush dulcimers to the new shellac and wax finish as of this year.

Still experimenting with another natural finish for the Warbler and Whippoorwill dulcimers. I have discovered that a few drops of Japan driers added to Tung oil makes it cure super fast, almost as I am rubbing it on. So at least two coats can be applied in a day, and a third the next day develops a very nice semigloss shine. This one will have to wait for more experimenting, but looks promising.

Two years ago I developed a completely different approach. Since I was a cabinet maker, I am know how to work with high pressure laminates (Formica). So I designed a dulcimer made of Okoume marine plywood that I could then cover with whatever laminate the customer chooses. They work just great, sound wonderful, are water proof, and stay in tune. And the design possibilities are unlimited. We have built a fair number. They never fail to get noticed. One of our friends had us make one for her the color of blue jeans. Another one looked like a beautiful piece of dark marble with mica flecks in it. There are wood grain laminates, some with textures, metals, and every color imaginable. Call us if this sounds interesting.