I understand that I am 12 years late to the party but having been a lab tech in a films company I appreciate this type of trial. One thing you could add to the trial is whats called a "cross-hatch" test which is quite aggressive but should tell immediately if there is going to be a failure. In the lab we use a cross hatch tool but you can use a razor knife and create a series of cross hatch cuts, cover them with different types of tape, allow different dwell times and then peel the tape off comparing how much finish peels off.
I have put multiple coats of Amber shellac on 6 panel pine doors and followed up with 2 coats of poly. While I haven't tried pulling the finish off, I can tell you after several years, the doors look wonderful. I used shellac to color the doors because that is the wood finish throughout the house.
Thank you! Your testimonial is good enough for me to try it. I am applying it to what I believe to be pre-select brick. I will just check to see which has a better heat resistance because the brick surrounds the stove.
I used 1 coat of Shellac under 3 topcoats of Polyurethane on my workbench and it has held up perfectly under lots of use for close to 2 years now. I did that based on this video and have never regretted it. Thanks!
In the woodturning world Shellac is consider "universal finish" meaning that anything can go under or over Shellac. That has been my experience. I hope you keep this boards for at least year and give us an update. I enjoy your videos very much, thank you.
Had the nicest day today went for supplies at HD and didn't have enough, had to put the shellac back. This gentleman came up to me and gave me the shellac I had put back as a gift. I want to say thank you very much if he's from around here.
The real test would be to expose the samples to heat and cold, like setting them in a sunny window for a while then setting them in the path of an air conditioner. The expansion and contraction might then cause the poly to lose it's bond to the waxed shellac more easily than it would the other samples. I'm thinking along the line of old house trim which has been polyurethaned over and has alligatored over the years. The original oil varnish finish is slightly gummy compared to the more brittle polyurethane, so the poly cracks up and floats around like sheets of ice on water. Of course, the old house trim would have a considerably thicker layer of finish than your samples, but just a theory I feel worth sharing.
To support what Mark is showing us. I have done linseed oil, a spit coat of waxed shellac and 2 coats of water based poly all in one day with no issue what so ever - so yes it can be done!
we used shellac as a sealer on stained oak staircase, then put 2 coats of oil based poly. We had major issues with that staircase's finish, cracking, peeling. So yes indeed waxed shellac under oil poly does certainly cause issues in the trade.
@@phantomcreamer I think the difference is that he was using a water-based polyurethane in this video and the man used in oil based polyurethane on the staircase
Great demo! I appreciate letting us know to use shellac under polyurethane for drying purposes. Usually I am waiting ten hours to put the second coat on and your first coat over the shellac looked great.
Thanks! I’m a baby woodworker and was alarmed at the hyperbolic naysaying about shellac under polyurethane. Thanks for your advice and exploration of the options!
I recently saw your other video about shellac and stain vs gel stain. This info is so useful. I'm planning to apply stain to some 100 year old pine and poplar repurposed from an old piece of furniture. Thanks very much for your videos!
I sure hope that you are right because I just did a floor with poly over natural shellac. In a week or so I may even do the duct tape test as you did. Love your vid !
The one thing I could think could cause some problems having shellac under the poly would be in a very specific situation. First we would need to have a thicker layer of the shellac under the poly and second long exposure to temperature differences, given that the shellac layer is thick enough to expand so different from the poly that would eventually peel, but than again any other type of varnish over shellac would do the same thing... man this is the reason I watch your channel all the time, very clever thinking. Thanks for the video!
recently finished a partscaster guitar...used bullseye amber shellac on a maple body to match the color of the neck..the neck was a gloss finish the shellac was not the same gloss..which i wanted..so rather than start over i used the hand rubbed gloss poly over the shellac..it turned out great and 2 months later no negative signs...quick tip..for a yellow/honey/gold finish..i gave the guitar a yellow stain first..then the amber shellac..it turns out great the way the yellow underneath shows thru the amber..thanks for this video..i'd never have tried it until i saw this..
Try a natural brush for oil-based poly. Keep the synthetics for water-based materials. The natural bristles will allow you to lay a smoother layer of finish. You might also try diluting a little with mineral spirits to help the finish flow a little better.
I totally get what you mean by testing results for the way you would use it. Just to add to the mix, I did floor sanding/refinishing for years and do wood turning now. We could tell if any wax had hit the floor (even overspray from a can of Pledge) because the urethane would wrinkle immediately. But I use the regular shellac, cut, as one of my sealers for turning without any issues.
I have used zinzer shelac over various brands of gell stain that were brushed on and left to dry instead of wiping it all off, then finished with waterbase Varathane . I've done it this way for many years. My wife does the stripping and staining and I had to come up with something to make her method work. I have a large house full of beautiful re finished thrift store furniture that says this works just fine. You do have to make sure the stain and then the shelac are more than thoroughly dry or your going to be re stripping and starting over. Shelac over minwax gel stain is difficult, old masters gell stain is good, i've put Varathane directly over it once or twice but I only use the shelac in between anymore. Try a test piece before you do a big area.
12 years late. But, there IS a difference between waxed and non-waxed shellac when you're applying stain (as opposed to poly). You get a much more even coverage of stain with the non-waxed shellac. I've done with this with cherry a number of times. In each case, I seem to get more even coverage of the stain with the NON-waxed shellac, then I cover the stain with a top coat. In my case, Arm-R-Seal. Thanks for the tips, Mark. You got me started down this wonderful road. Much appreciated.
If you want a shellac finish, you can certainly use that over the stain. I wouldn't recommend staining after the shellac application unless you cut the shellac by quite a bit first. Shellac will seal the surface and prevent the stain from absorbing as much as it would in raw wood.
The Wood Whisperer I had that exact question and now it’s answered. Making a lazy Susan and want to seal it , but want to stain first. Now your non waxed says it’s sanding sealer, is that still shellac?
I was wondering would this work on a Redwood fence that would be in the sun? My friend turned me on to this video...should I put the Shellac on first then my stain, then Shellac again?
The way I was taught to test for adhesion problems is to score and X into the finish with a sharp knife. Then press a piece of tape down firmly over the X and yank it off quickly.
Exactly as you wrote. The presentation showed nothing without a cross-hatch adhesion test. Absent such a test, the presented information has little value in helping us to select and choose the right finish.
@ironlionkalo Shellac pretty much binds to everything. That's what makes it such a great sealer. It can seal off impurities and oils in the wood, allowing your other more sensitive finishes to bind.
I've tried using Shellac tinted with stains on guitars. I've applied a few coats of shellac until I got the colour I was after. Then sprayed a protective layer of acrylic spray paint. It does adhere somewhat, as long as there's no pressure on the finish. Where I've applied pressure (like screwing in pickup rings, tuners etc), that's where the finish will unbind from each other. It may have also been not allowing the shellac to dry for long enough (I can't remember how long I left it, but I'm sure it was only a few days at most). Could be the stain not allowing adhesion.
Having used shellac under urethane for over 30 years I can tell you I have not had issues. If you are unsure the use varnish over the shellac then urethane if you like. Personally, I like the look of varnish over shellac buffed to a matte finish as it is the least cloudy of them all.
just finished a guitar build..used oil based stain on the body in a tan color..the neck was the vintage yellow/orange color and did not look good with the body color...so instead of sanding and restaining the body , i put about 3 coats of zinsser amber shellac over the body after i gave it a light sanding with 400 grit...well thank God the amber shellac added just the right touch of yellowish/orange color that the body now goes perfectly with the neck...i also love the fast drying time of the shellac...i did not check for compatibility of shellac over oil based stain...but so far so good.
Just built a coffee table from reclaimed old-growth doug fir. Did multiple coats of unwaxed shellac for color and depth, and then 4 coats of minwax whipe-on poly for toughness. Looks so so so good. Just one example of why someone would use poly in a thick layer under poly.
I like the way you covered this, it made sense to me. I too would like to see more on the subject of spraying finishes rather than brushed. You do a great job and its probably only a matter of time before you're picked up by a big network, Norm..., er, uh, Marc. I'll be checking more videos out, I will be making an end grain cutting board soon. -Ken
The guy at the paint shop hands me a quart of shellac and a quart of poly to treat my stained t&g. Says "this is what you need". Great. He should know. That's all he does. I get home. Read the labels and it tells me the exact opposite. Chit. I think maybe someone on the youtube tested this out. Sure enough. Many thanks to you woodwisperer.
I recommend doing this test on a contoured piece. Maybe a spindle or even a newel post. Maybe the adhesion comes into play on the edges. Then apply your tape across an edge. The flat board test is pretty much your optimal situation and rarely is that the extent of a finishing project. I appreciate your sharing this!
Thank you for this video! I just put spray poly over OBShine Juice... 1 part shellac, 1 part denatured alcohol, and 1 part boiled linseed oil... On a turned pecan wood bowl... So far so good!
Good video.. I have been using 50/50 (shellac/alchohol) on many different woods for many years. I have one piece of furniture I built for our own use about 25 yrs. ago. 50/50 to seal and pull up any loose wood fibers and 3 sprayed on coats of poly. It looks the same as it did when I made it. BTW white oak. I have to assume it is a CYA ploy on the part of the maker of the pollyurethane. Like you I am a bit mystified. Thanks for the tests.
You know it's guys like you and Stuby Nubs that separate all the Hype from facts and truths. You are right on. I have used all kinds of finishes on all kinds of woods and NEVER have I had the problems that you have exposed in this simple test. I do agree with you that there must be Some Kind of Condition that allows such statements of failure but as a general rule they are far and few between..THANKS FOR THE TEST
Shellac can be a sealer or a topcoat. But as a topcoat, it isn't quite as protective as some may want. Poly, on the other hand, is. So we often seal with shellac and follow up with a more durable topcoat.
Some problems only occur under certain conditions. Once a customer wanted the wood to be finished with a particular top-layers, so that the look and feel, and the gloss was the same as other wood. Some products of some brands have more solvents in them then others, sometimes the solvent of the top-layers is re-solving the layers already on the wood. But if only a very thin coat is being applied there is nothing to worry about.
Thanks. Your informative video saves me, as a total amateur, time and anguish over something that probably doesn't matter. But I enjoy the hobby. Even my wife had to laugh at measuring cups appropriation for the greater good.
I’m trying Aqua Fortis, followed by 1 coat dewax shellac, then 2-3 coats poly - it’s for a high traffic area kitchen island and this gives me faith it might just work! Love the look of curly maple on gun stock and gonna give it a try. Thnx Mark
I am a experienced home painter of 22 years. I have done many kitchen cabinets over the years. I have seen one fail. I tried a water-based varnish and found out that (when lightsanding) the varnish came off in flakes. It was clear that it was shalac. After 220 grit sanding the whole thing and cleaning with alcohol. I went out and got a oil based varnish and everthing was fine. I just resently ran into that customer and there has been no issues so far. I did that in 2002. I have had issues since.
Well its value in blotch control and oily woods is well-documented. Just do a few searches for info on that. As for saving time, you can use shellac as your first coat of finish and you'll be ready to apply your first coat of oil-based poly within an hour or so, as opposed to applying the oil-based poly first and waiting a day for it to dry.
@Shannariano Haven't done any impact testing. But I did do further adhesion testing using a Scotch tape test. I used an x-acto knife to create a grid of cuts and then put the tape over top of that. Neither duct tape or scotch tape could pull up any finish.
About five weeks ago, I finished the plywood surface of a new workbench with two coats of white shellac, followed by two coats of Minwax semi-gloss poly. So far, absolutely no sign of adhesion problems. I've used poly over spit coats of shellac for years and never heard that we shouldn't use poly over shellac. In my case, time will tell I guess, but hey, it's a workbench! I If it does start shedding off, we'll strip it and refinish.
I'm surprised to hear that they don't recommend using it under poly finishes. I always followed the advice of "The Furniture Guy", Ed and Joe. They use a spit-coat of shellac under almost all their finishes. I made hutch 15 yrs ago with a spit-coat of shellac and alcohol, then stain, then polyurethane, It worked perfectly and is holding-up beautifully to this day.
I once had a can of that Zinsser Shellac Sealcoat eat through the bottom of its own can and spill onto my cabinet. It did the opposite of a great finishing product. Suggest you decant into glass bottles for storage.
Yes you can. Shellac is nearly always a good idea as a barrier coat. But if the surface is fully cured, after a light sanding and wipe-down with something like denatured alcohol, you should be able to put down lacquer immediately and skip the shellac. But always test for adhesion issues in an inconspicuous area.
A standard way of testing the bond is to score an x with a sharp knife, then press some tape over the x. Give it a quick yank of the surface and see if the coating is peeled.
Great tutorial....personally I use the de-waxed spray can clear shellac...a light sanding and 3 coats of water poly. The shellac eliminated the grain raising of just the water based poly
I wish I knew how to put a picture with my comment. I am not a wood whisperer BY ANY STRETCH OF THE IMAGINATION. I just piddle around the house. I removed the back seat of my 2002 dodge in 2008 and put 3/4" wood n for my 2 dogs in. I used Amber shilac and then put either polyurethane or spar urethane ( I honestly don't know the difference) I just removed it a few weeks ago and it looks great. That is 10 years in a garnet/ maroon color truck ( hot as crap in the summer) and dogs in it every day. I don't remember every step of the process I used. Maby neither of the 3 of us knew we were not supposed to work with each other and we just got the job done. Thank you for telling me that Zinzer or whoever says it would not work 😂 I promise I wouldn't tell my piece of plywood. Sometimes ignorance is bliss.
@TheWoodWhisperer I just thought it was great that someone actually took the time to test it and share the results. A fine job you did of it. But after careful consideration I opted to skip the shellac and just use several coats of poly. I treated the cedar with a pre-stain conditioner before staining so shellac would be overkill. I'm still waiting for the stain to settle so if this is a bad idea I'm all eyes.
I'm working with the same three finishes right now and was asking the exact question. After seeing this I'll try the poly on the back side of cupboard doors I'm refinishing. If it works the fronts get a coat too. thanks
A finishing expert explained to me that shellac becomes a very hard surface after drying; which severely restricts adhesion for the next different coat. Max, a couple of hours, for adding the next different coat (soonest possible best), after that the shellac fully cures and becomes too hard. If wait too long can recoat Dry shellac with more shellac (or perhaps just alcohol?). Waxed shellac was not recommended as an undercoat (adhesion & interaction problems).
Waxed shellac is great for a complete finish and would not be the best for undercoat or for cutting with other finishes. Nor would I try to dilute it with alcohol.
I watched this because I have had to use this method to put water based poly over an oil based stain on cherry trim. I was originally using the waxed shellac, and when I shot the nails into the trim boards, the poly would crack and peel up around the the area where the nail was driven in. This did not happen when I switched to the sealcoat dewaxed shellac.
- over 5 decades in the trade / www.finishconsultant.com and NO, Don't do it. In the first place Shellac is 'old world' chemistry: dissolved Cicada husks (think locusts). It is brittle, and poor performance against moisture. If you are going to use solvent base Urethane(s) any polyurethane, catalyzed or single stage, start out with urethane as a sealer (thinned 10% OK) then add each coat within a 24-48 hour window, The reason IS urethanes 'cross-link' molecularly, giving the strength urethanes are known for. If you re-coat a urethane (years) later by scuffing up between coats, will give a physical bond, but are 'suspect' because they will not cross-link.
Surprisingly, for an expert you are wrong on at least two points. Shellac is obtained from the Lac scale insect (Kerria lacca), from its laval secretions, not from its husk, and lac insects have no relation to locusts nor cicadas. Merely being an old world technology has no adverse bearing on anything's performance, or we'd have to throw out the wheel.
Absolutely. Shellac is one of the most useful and beautiful finish rd available. There a reason it's been around so long and polyurethane s keep getting reformulated all the time.
Just a guess at this but it may be that the light sanding removes any light skin of wax this allows for good adhesion. It may not work over a built up coat of shellac. If multiple coats of shellac are built up there is no need to put another finish on, if other finish is used just use the shellac as a wood sealer.
I really appreciate finishing as the topic here, almost can't have enough videos about the subject. I have a great book that really opened my eyes to the possibilities, "Wood Finishing with George Frank" by the late George Frank I would highly reccomend it.
I honestly don't remember exactly what I used but it was most likely just a can of wiping varnish. Significantly thinner than your regular variety of varnish, which makes it nice for wiping. Not ideal for this experiment though...but I was trying to get rid of some stuff i had in the cabinet. :) Honestly not sure on the coating thickness....sorry my friend. Maybe I should send some DD your way? Shipping wouldn't be too bad. :)
I've also tried many combinations including water based polycrylic on oil based stain. It's all about drying, humidity and temperature. We know about that in MN.
IF the wood is thirsty, just give it more. Eventually, you have to end up with a gloss layer on the surface. At some point the wood will be completely sealed and you'll be layering finish on top of finish. So my advice is to add more/thicker coats and sand with high grit (600) in between. You'll get to gloss eventually.
One interesting test would be to put the duct tape and the aluminum tape over the damage caused by the epoxy damage. again, it would only show how damage can continue based off an initial damage, but that might be a factor in why people say not to do this. Great video though, Thanks!
Well, that's definitely not my favorite way to change color. It almost always ends up less attractive that one would hope. If the surface is properly prepped, you might be able to get away with polyshades. I have also hear of some folks using a gel stain and then coming back with another clear coat on top.
I put polyurethane on a surface of a bookcase, with an unknown type of finish. The poly did not sink into the wood. It stayed on the surface and formed a soft sticky gummy coating. Even a few years later, it stayed gooey. I wound up having to scrape the goo off. It took a lot of elbow grease, solvent and patients. Most people would have tossed the bookcase away, and I thought of doing so, many times .
Depending on the amount and concentration of shellac, you will indeed prevent the oil-based stain from penetrating. But a very dilute washcoat of shellac will still let some stain through. One of those things you need to test on scraps to see how things are going to pan out.
Great video. Very much appreciated. I'm building wall and base cabinets for my basement and plan to do a seal coat of the Zinsser Sealcoat with a satin clear polyurethane topcoat for all interior surfaces. I want to do this for the inside of the cabinets so they'll not be so dark inside. For the exterior though, I'm staining the wood with Minwax Golden Oak. My question for the external is, what do I lay down on the plywood as I stain and then final coat with Polyurethane? Would I use the Zinsser Sealcoat at all on the exterior, i.e., sides, frame and doors? If so, in what order? Sealcoat, stain, poly? Thanks.
Bingo. Thank you for that. Shellac is a really cheap floor finish but a good prep for poly. Shellac it and screen it with a power buffer and then poly.
Keep those boards somewhere that'll see humidity swings. I'll bet the adhesion issue happens after some expansion and contraction cycles. The wax probably doesn't expand at the same rate as the poly. I'll bet this is a "over the course of a year" issue. Incidentally, sharpies are alcohol based, so don't use them with /under shellac. Oil based paint markers for shellac, and sharpies for poly.
I thin k since the poly is still fresh and hasn't aged, it's holding together by itself strong enough to resist being pulled off with the tape. However, if you did this with a piece of furniture that was then used for 2 years, you might very well see the poly getting weaker and flaking off the shellac.
If you put a coat of shellac on the wood like you normally do, over bare wood, could you put BLO or a stain/gel over top that and then a protective coating (poly, epoxy etc)?
You can do that but you need to experiment to see what you like. I personal just like Shellac on its own or with a little wax to finish. I have cut Shellac and varnish finishes and other finishes as well to experiment. You will not like all the results but that is personal taste. If you want to make cheap quality furniture then shellac straight from the can will be an excellent choice. You can achieve a really high end look.
Sure. But it's probably a little overkill to sand with 2000 each time. I'd sand with maybe 400-600 until the final coat or two, then switch to 1000-2000.
Well the color of the finish on the wood - is the major difference in. the results of this test. If you do not want the amber golden finish color - use the De-Waxed Sealer (under the Poly).
I appreciated the test. I have never used one finish over another but it is good to know I could. Maybe keep the test pieces and at a later date, show the results?? Good stuff! Keep it up : )
a liquid called wood knotting which is used over here in UK to stop wood knots bleeding natural wood glue under warm temperatures is Shellac based, a pretty robust sealer don't you think..
I realize this is a old video...but if someone was worried about waxed shellac. The proper test would be to score an x with a razor blade then apply tape and pull.
Hi Marc. Do you see any issue using shellac under water based poly? I make a bunch of cornhole boards and am thinking that a coat of shellac could save a few coats of poly. As usual thanks for all the videos!
Thanks for the video Marc, I've found the same results in my experiences. Have you gone back to see if these boards ever dissolved as was claimed they would do by some other commenters here?
