Shellac - finishing disaster

[Darius Ferlas]

I finally got around to using Zinsser SealCoat, which is de-waxed clear shellac. I was supposed to live happily thereafter. That kinda didn't work out that way.

I read around the forums how wonderful shellac is and how easy it is to apply and bring to a nice uniform shine. I did come across a warning somewhere on SMC, that newbies should start their adventure with shellac by using a 1 lb cut, so I thinned the shellac I bought. The batch was dated 2009 so it still has about two years of shelf life, as per Zinsser specs.

First the problem started with the application. Brushing yielded rather significant witness marks so I decided to sand those out. I let the shellac dry very well and next morning I started to sand the surface with 120 grid to get rid of the overlaps. I noticed tat my ROS started gumming some spots up. So I decreased the grid (down to 80) and that seemed to have helped. My next step was re-coating with an even thinner shellac. The result was nowhere near the museum quality but it was much better than brushing. At least some of the faint smudges seemed thin enough to be taken care of by some 100G sanding. Again, gumming up. I went down to 60, then 80 and ended up at 150.

That's when I decided to apply a coat of Pratt and Lambert #38. The varnish is astounding and unbelievably easy to use but... I got blotchiness, which I assume is from a thin but gummed up shellac.

I am considering various options, one being complete stripping of both finishes with a more aggressive grid (40, or even 36), then working my way up to 150 again.

I am attaching a photo of the disaster. The rightmost darker spot is intentional, I know, that little heart shaped pair of knots is a bit tacky but wifey likes it. The blotchiness is mostly the large, darker spots along the center line of the table and within the left bottom corner around the breadboard area.

Help!

[Prashun Patel]

From here it doesn't look like a disaster.

One thing to know about shellac is that since each coat fuses with and melt into the previous coats, there's no need to sand so hard between coats. Certainly, there's no need to go to 120 down to 100 down to 100 and down to 60! Sanding between coats should be in the 220-320 range just to remove nibs.

To remove the ridges you mention - and I get them too - the best is to use an alcohol dampened rag / pad to melt and smooth out the ridge. You might mess up any sheen you have there, but you'll be able to get that on the next coat.

That brings me to the next point: don't work the surface by painting it many times. Don't lay down a thick coat like with varnish. If you have uneven or brushy strokes, have the discipline to let it be and to fix it on the next pass. After a few coats, it tends to even out - magically.

Padding is also always an option. You can do it 'properly' by making a 2-layer pad, but frankly, I'm able to pad it on good enough with a quarter piece of a shop towel folded a few times. *Don't dip*. Squirt a little shellac onto the rag (this is the reason why padding works). Wipe across the piece until it runs out, then squirt more. Because you are putting so little on, it dries super fast, and does not drip, so by the time you get to the bottom of yr piece, you can put on another thin coat from the top. Keep doing it until yr rag/pad starts to drag. With a properly formed pad, you won't have to reload or "charge" it so much. With my shop towel, you're basically constantly charging every foot or so. However, with a squirt bottle, it's easy. In fact, when you get the feel of swiping, you'll be able to even squirt a little right on the table, and just wipe it in.

The big key w shellac is not trying to get a perfect sheen. Just focus on not getting nibs and runs, and trust me, after several coats, your even sheen will magically appear. Don't try to get a thick or built up coat. With each subsequent coat, yr not so much putting on more material as you are just trying to fill in gaps and blend everything evenly.

Saying shellac is easy to apply is a bit misleading. What people REALLY mean is that it's easy to FIX mistakes on the next coat.

Sorry for the ramble...

[Mike Null]

With all the problems mentioned I am still a big fan of shellac. In most cases I prefer to spray it but even when brushed I don't use coarse grit paper. Sometimes a little steel wool and dna will work wonders.

[Darius Ferlas]

Shan, thanks for the reply.
Right now I am beginning to understand the mistakes I made while applying the shellac. Too much, too slow, too much overlapping and with the humidity being low. My initial attempts to sand out some overlaps out were with higher grids but since that didn't seem to be of any use I went down to more aggressive grids.

At this point I decided I need to strip the finishes down to bare wood and start again. It looks like I have tried to bite more than I could chew, especially on a large surface like that table.

Luckily, the varnish was still wet when I took the picture in my post above. With mineral spirits it was pretty easy to wash the coat away, hopefully all of it.

Right now I am looking for the best way to remove the shellac. Would then denaturated alcohol be the way to go, aggressive sanding or a combination of the two?

For better clarity of why I think the finish is a disaster I took additional shots zoomed on the blotchy areas. They do stand out and certainly look like there is a finish problem there. With the glossy varnish atop the wood it looked even worse.

Mike, what is dna?

[Joe Chritz]

DNA is denatured alcohol short hand.

If you are using a wiping varnish why use the shellac at all?

Shellac is very easy to spray, everything else is a bit harder. It is a put it down and don't touch it thing. You do not have the forgiveness of a slow drying oil varnish.

You weren't using that foam brush for the shellac were you?

Joe

[Faust M. Ruggiero]

Joe,
Here are two consoling thoughts. First, you can strip and re-apply a finish. In fact, lots of finishes like being applied over shellac. Make sure you remove as much as possible and sand really well.
The second consoling thought is this. Some of the best finishes I've ever seen were second finishes done over a poor first effort. You are armed with more knowledge than you had during the first attempt and the wood is now well sealed. The next one will be great.
fmr

[Prashun Patel]

Your finish probably isn't responsible for the blotch. The blotch is a function of the wood and the preparation. In fact, many people recomend using shellac precisely as a blotch preventer.

To what grit did you sand BEFORE you applied anything? Did you color the wood with anything? Doesn't look like it.

[Michael MacDonald]

DNA is denatured alcohol short hand.

If you are using a wiping varnish why use the shellac at all?

Shellac is very easy to spray, everything else is a bit harder. It is a put it down and don't touch it thing. You do not have the forgiveness of a slow drying oil varnish.

You weren't using that foam brush for the shellac were you?

Joe


so are foam brushes bad for applying shellac? I have used them recently, and thought they were OK... I saw shawn's approach described, and may give that a try... prior to the foam brushes, I was using natural brushes and didn't like it...

[Darius Ferlas]

Joe,

spraying is not an option for me at this point. I may look into it after I get some other shop equipment priorities taken care of. I didn't use the foam brush for the shellac but I did use it for the varnish and that part worked beautifully. Also, Zinsser lists foam brushing as one of the acceptable options for this product.

Faust,

I am indeed trying to see the glass half full here. A little extra sweat and the delivery schedule postponed. I do want to figure this shellac out as I appreciate its aesthetic and chemical value since, at the very least, it affords a wider range of compatibility between finishes.

Shawn,

In a way I feel you are right, the finish material was not responsible for the blotching. My inexperience was. The blotching occurred in the general areas where I remember some of the gumming up to have occurred. Before I applied the shellac the whole surface was originally sanded following this schedule: 60, 80, 120, 150, 180, 220. I applied no coloring to the wood, or to the finishes at all.

The varnish is stripped so now I have even more questions:



Any tips I should be aware of for washing out shellac with DNA?
Will the glued joints be affected? (I used TB III)
I read somewhere that turpentine would retard the drying of the shellac, but I am unclear about how much turpentine to add, what drying times to expect etc.
if turpentine is not such a great option, would then some DNA or other alcohol be a good thing to use in lieu of sanding paper to knock down any ridges?


Again, I appreciate all the responses.

Darius

[Steve Schoene]

Some comments. First lets start with your numbered questions.

1. You don't really need to remove all the shellac, just remove enough so that if any remains it says smoothly without defects.
2. No, it won't affect the glue.
3. Yes, it will, but I wouldn't. Shellac can be easily enough made to work just fine without that. I'd persist a little.
4. Adjusting your technique in applying the shellac is the easiest. A little sanding with 320grit --by hand, NEVER with ROS--should be plenty.

Now some things about wood preparation. If your wood has pased through a planer, or been straightened on the jointer, there should absolutely be no reason to be using 60 or even 80 grit sand paper. They just put in large scratches that take lots of work to remove. If you are applying any film finish, then sanding to 180 grit is generally all that is needed, but there is no harm in 220. If you use an ROS for most sanding, remember that you should finish off by hand sanding with the grain, using the same grit as your final ROS grit.

As far as applying shellac. Shellac must be applied quickly and confidently. You can't apply shellac and then brush in out like you might with varnish. Padding is generally the most forgiving. Keys to success are to work quickly, never go back to get a missed spot, and the instant you feel any drag of the pad (or brush for that matter) STOP.

I don't like ordinary brushes of the sort you might use for varnish. They lay down too much shellac and don't do it enenly enough. For brushing I much prefer a fine sythetic bristled waterclor wash brush from an art supply store. (Taklon gold bristles are good.) These brushes don't carry much shellac--you do have to dip them a lot, but, they leave no brush stroke marks. I brush on a thin stroke. Then when I start a new stroke I begin a shy inch from the end of the last, brush toward to previous stroke, and then immediately stroke back the other direction. The ONLY spot that is ever touched twice by the brush is that first inch. That prevents "lump" where the brush touches down. In general, if there are small lumps or missed spots the next coat will deal with that as long as you don't skip the same place again.

You need not sand between coats of shellac unless there is some screw up you want to fix. And then you only need 320 grit by hand.

When you have build a sufficient film of shellac then you can complete the process by rubbing out the surface to remove any defects and achieve whatever gloss you want. Shellac doesn't need a thick coating, but get enough so you can sand out defects and rub to the desired sheen without cutting through. For rub out I start with 600 grit (400 if defects are larger), and then jump directly to 1200 grit, or 2000 grit if I am going to gloss. When all the 600 grit scratches are removed, I then use rottenston to achieve a glossy finish or pumice to achieve a satin sheen. Polishing compounds work well too.

[Neal Clayton]

so are foam brushes bad for applying shellac? I have used them recently, and thought they were OK... I saw shawn's approach described, and may give that a try... prior to the foam brushes, I was using natural brushes and didn't like it...

i can't think of anything those foam brushes are good for.

i use a regular ole BORG china bristle brush. no need to use a really good brush, it won't make that much difference since it dries so fast.

same way you paint anything else. saturate the brush, shake out the excess, full-length strokes overlapping as little as possible.

also, i know that zinnser claims to be able to preserve shellac longer than normal with additives, but i wouldn't use a can older than 6 months. it does have a shelf life. won't affect the appearance that i know of, but will hinder it from drying if it's too old.

[Steve Schoene]

Zinnser doesn't use additives to extend the shelf life, it is more what they "take out or alter " in the processing. I'd also be a bit sceptical of the stated life, though it depends on the application as to what is "fresh enough"

[Prashun Patel]

i use a regular ole BORG china bristle brush.

Interesting. never tried that; I always used a synthetic brush, thinking china's reserved for oilbased finishes.

[Neal Clayton]

Interesting. never tried that; I always used a synthetic brush, thinking china's reserved for oilbased finishes.


ironically, the best brushes i've found for brushing shellac on existing wood moldings, which of course has some vertical and upside-down surfaces, are these (http://www.amazon.com/Purdy-Corporation-024425-2-1-2-Bristle/dp/B00002N8YJ/ref=pd_bxgy_hi_text_c). 12 bucks at the borg. and yea, they're the ones typically marked as "for oil paints". i think the softer white china bristles help with not pressing too much shellac from the brush. the stiffer black bristled ones seem harder to control for me.

here's a normal, hi-res, and from-a-distance on a wide doorframe finished with garnet using the above cheapo borg purdy brushes. you can see some faint brush lines in the glare on the close up pic, but i think it's good enough for gubment work ;). probably would need buffed/polished if it were furniture, but for my purposes it's plenty good enough without much effort.

[glenn bradley]

Sorry you had that experience. Shellac is my "go to" finish. I always use a pad. First coat is generally a 1lb cut unless am just using it as a barrier or sealer; then I'll thin even more. Second coat (and any more, if required) are 2lb cut (Zinsser out of the can).

Things that work for me:
1. - pad the shellac on:
==> for large surfaces I use a cheese cloth wad inside a smooth cotton wrap; otherwise, folded paper towel pieces.
2. - never go "back over" an area:
==> any goofs will vanish with the next coat 30 minutes later following a 320 - 400 grit de-nib if required.
3. - do not try to apply a thick film as with a varnish:
==> shellac does not "level out" like other top coats; it sets too quickly (at least in SoCal).

I would urge you to try again on some test pieces. You may find it to be a very useful element in your finishing arsenal.

[Jim Becker]

so are foam brushes bad for applying shellac?

A good quality brush and good technique are what is required to apply shellac by brushing it. The former is self-explanatory...a great brush will have a "feel" to it that is, well...great...and it will hold the finish for application in a consistent manner. Technique is something that must be learned through practice. Brushing shellac is not the same as brushing varnish and most problems with that form of application are due to one trying to do it like they have with varnish. You have to lay it on quickly with no over brushing outside of a quick and immediate back-swipe or two to level. Don't keep working it...it dries extremely quickly and you have to move on to keep a wet edge. If you miss a small spot, you can get it on the next application. Also, be sure to break any sharp edges while sanding to avoid finish piling up at said edges due to surface tension.

Practice...practice...practice. And Zinsser Seal Coat is completely brushable with out cutting right out of the can. (It sprays beautifully without cutting, too)

That all said, I only brush smaller projects/project components when it comes to shellac. I prefer to spray it for larger surfaces for both speed and to reduce the chance for brushing mistakes.

[Ken Fitzgerald]

Oh boy am I glad I read this thread. I have a cherry table I'm still fighting with and gave up in disgust. I think I'll reapproach it.

[Dee Gallo]

I just finished doing 10 doors, which have 6 panels, so they presented plenty of places for problems. I got excellent results by doing it in this way:
1. Sand with ROS to 200 grit, vacuum and tack cloth it off
2. Apply shellac cut in half with DNA (I use 1/2 orange, 1/2 clear) with a China Bristle brush, long lines so you keep a wet edge at all times to avoid lines across the grain. BTW- these brushes shed - when using a new one, expect hairs to come out. When this happens, simply push the brush tip forward over the hair and the brush will pick up the stray hair so you can pick it off the brush and keep going. After applying, make fast feather light passes over the getting-slightly-tacky shellac to smooth out any lines.
3. This will dry almost immediately. Give it a second coat without sanding in between.
4. Use only no-fill sandpaper (like from Norton), 400-600-800 grit (increasing in each step) to sand by hand with the grain. It takes barely a swipe to get it super smooth and the paper will not clog. I use a sponge block instead of wood in case it bumps something there will be no scratches.
5. Tack cloth to remove any dust and put another coat of shellac. Repeat until you have 4 coats on. Let dry over night between 2nd, 3rd and 4th coats.
6. Tack and apply a cloth rubbed coat of ZAR Poly-Tung Oil satin finish to preserve the shellac from water damage.
7. Sand it with 800 grit to silky smooth.
8. Spray some household furniture wax on top and buff. It will feel like glass.

I know this sounds like over kill, but you only want to do this once, it is not hard to do and is well worth the deep patina and smooth surface you will achieve. This kind of "old world" technique will make your work glow. Any blotches you think you see in the photo are from the flash, not on the door.

cheers, dee

BTW Ken, this poly-tung oil does a spectacular job on cherry, using the same procedure (3 coats poly, without the shellac).

[Darius Ferlas]

A lot of great information, much of it pointing out what I definitely agree with - lack of experience. So far I can list the following sins I have committed against my shellac finish:

- not sufficiently good brush
- terrible brushing technique
- sanding with a power sander instead of hand sanding with the grain
- using too coarse grid in my attempts to merge overlaps

Right now I am working on the removal of the shellac. Despite copious amounts of alcohol (methyl hydrate 99.9%) the shellac won't just dissolve and vanish with wiping. That might be still some of the varnish I didn't manage to fully remove. I am getting some shellac residue on the white cloth I use to wipe it but some of the shellac shine still seems to remain on the surface. And that DNA dries FAST! I feel like I need to try and use some #0000 steel wool as my wiping rag.

The whole thing is even more depressing because (as one poster noticed) I didn't even have to use shellac on that table top. In part, the process was my test before moving on to water based finishes which, as far as I know, won't give me as much grain pop as oil based varnishes. I wish I conducted my tests on a smaller piece, and on one not at as an advanced stage.

[Neal Clayton]

no, you don't have to use it, but it's worth learning how, imo.

as dee mentioned, there's a kind of 'old world' look to shellac that's not easily replicated.

and the technique with a brush will apply to lots of finishes, not just shellac. so if you get to the point of brushing shellac well, brushing finishes that are easier to work with should then be child's play ;).

[Darius Ferlas]

Neal, I am definitely going to continue using shellac, despite my bad start. I like the color tone it gives and that "old world" feel to it.

Dee, I think shellac finish on raised panel doors you posted are a bit out of my reach at this point. For now I am happy I finally managed to get rid of my mistakes and applied 2 coats of shellac on the flat surface of my table. I can't fathom I'd be able to come even close to your skills at this stage of my shellac'ing experience.

Thank you all for the precious tips. Every single one of them proved to be of great help.

[Neal Clayton]

doing intricate things, like a door, with a brush and shellac is what will help with other brushed finishes regardless of what they are, that's kinda what i was referring to.

planning where to start and where you're going to wind up when the brush is empty is a lot of that. and that will transfer over to any finish, regardless of what type of finish it is.

shellac is the perfect finish for brush practice, because it's cheap and easy to fix if you make a mistake ;).

[Dee Gallo]

Neal, you are 100% correct. Shellac gives you an easy way to learn the "feel" of brushing a finish because it will flow, grab and stick at different times, just like other finishes, but in a shorter time frame. Handling a brush has a lot more to it than just dipping and dragging if you want to do it well, but it is not hard to learn.

Unfortunately, the majority of people will try to learn their first lesson on an important piece rather than a practice piece. That's the only mistake they can really make.

:) dee

[Joe Chritz]

I wish I conducted my tests on a smaller piece, and on one not at as an advanced stage.

You have learned the first and most important "rule" of finishing anything.

School is out for the day, grab a brush and get to work.

FWIW, spraying takes all the work out of shellac. ;)

Joe

[Neal Clayton]

Neal, you are 100% correct. Shellac gives you an easy way to learn the "feel" of brushing a finish because it will flow, grab and stick at different times, just like other finishes, but in a shorter time frame. Handling a brush has a lot more to it than just dipping and dragging if you want to do it well, but it is not hard to learn.

Unfortunately, the majority of people will try to learn their first lesson on an important piece rather than a practice piece. That's the only mistake they can really make.

:) dee

yep, i agree that it's not hard to learn. only took me a few tries to get the hang of it when i learned, so it can't be brain surgery.