Hi folks
Both the Zinnser clear and amber shellacs specifically state on the can that they are not recommended for use under polyurethane. I understand from reading in this forum that this is because they are not dewaxed. I also understand that the Zinnser sealcoat is, however, dewaxed.
My question is, if one wanted the aging effect of a wash coat of amber (1 lb cut over maple) to be followed by a poly top coat, could one effectively follow the amber coat with a coat of the sealcoat, thus rendering the poly warning moot?
Does the “blending” characteristic of shellac allow the wax in the amber underneath to still be a problem?
Some thoughts on the whole process:
1. Don’t want (for several reasons) to use shellac alone as the surface coat.
2. One could tint the sealcoat with a wizard tint type dye to mimic the amber, but I’m not sure I want to spend time fussing around. I do have honey amber and a brown dye on hand.
3. I have run poly over the clear and amber in past projects with no immediately evident problems, but always after using a glaze between the shellac and the poly topcoat. Only time will tell if I’ve goofed here.
4. The project involves 18 panels, approx. 18″ x 36″, with mdf core 1/4 maple beadboard framed by 3 1/4 x 3/4 solid maple. I plan on prefinishing the parts prior to assembly, at least through the shellac phase.
5. All of this is contingent on my being able to find a quart of sealcoat prior to when I’m ready to finish…..both local stores have the other two in quarts, one has a gallon of sealcoat, neither has just a quart of sealcoat, although one promised to start carrying the quart size when I suggested they do so. I’m guessing that buying a gallon will result in a lot of it going to waste – classic case of false economy. SIGH!
Thanks in advance.
Replies
I've been using Zinnser sealcoat for about 4 Yrs under waterborne laquer and have great results. The sealcoat already has an amber tint to it, whether or not its enough for you, I do not know, but it works great on hickory tinting the white sapwood to blend better with the darker heartwood. I use it on everything as it will seal oil stain so that the waterborne will not have issues and also it gives the wood a warm feel. Personaly I wouldn't put it over a waxed shellac as I think your asking for problems, but then I may be wrong
I would not try to mask the waxed shellac with coats of dewaxed shellac, or ignore the warning about applying poly over shellac with wax. You might not notice problems when finishing, but adhesion will be a problem. That poly will separate or flake off when banged or scratched, and poly (unlike wonderful and beautiful shellac) is really tough to repair well.
But the real question is why are you so eager to rush into doing a finish on a project that you obviously care about it looking good for years to come? Can't it wait a few more days while you get the right supplies?
I would suggest that instead of limiting yourself to what shellac you can find in a local big box store, order some dewaxed amber (or garnet) flakes from an on-line supplier. I've found that http://www.shellacfinishes.biz has good prices and quick shipping, and there are many on-line other places to buy colored, dewaxed shellac. Tinting Sealcoat is also a reasonable way to go.
With dewaxed, colored shellac, you can safely ruin ... I mean, add a top coat of poly to your panels.
The best option is to use whatever shellac you want. Then use a non-poly varnish which has no problems being used over wax containing shellac. A non-poly varnish will give you a better appearance than poly varnish.
Could you recommend a good non-poly varnish? I am about to finish a plywood and curly maple display cabinet. Three plywood cases, curly maple face frames, door frames, base, and end panels. I anticipate doing the first coat in unwaxed shellac (Zinzer) and then three coats of varnish.
This will be new for me since I have previously always used polyurethane without the shellac seal coat, but am intrigued with the potential for better clarity and easier reparability using an oil varnish.
Mike D
Well......I weighed all the options, and took a plunge.
I decided to go with all shellac on this project. This is a first for me.
I started with a 1 lb cut of amber, followed by two coats of clear, also about a 1 lb cut.
The results are mixed, as may be expected when mounting the learning curve.
Problems encountered:
1. Rapidly "slopping" on the first coat, ala Frenchy, left amber overlaps that the subsequent coats did little to blend. Perhaps if the subsequent coats were all amber this would have been better. Live and learn.
2. The first brush I used was a 2 1/2" Purdy natural bristle that I had let go stiff with shellac from a previous project. Soaking it in denatured alcohol did indeed soften it in quick order, as per what I have read, but its bristles flared, making accurate "cuts" nearly impossible, hence most of the overlaps. On the second round of panels, I switched to a 2" that had never seen shellac, and the going was considerably better: no flare, much better control. I cleaned the 2 1/2, hoping that it will recover, and let the 2" sit, planning to soak it when I get back in 2 days in the thinned shellac rather than in straight alcohol. I'm hoping this will make a difference.
3. The sheen after the final coat was, as I expected, glossier than I like, and the finish was not particularly level. It was neither too difficult nor too time consuming to rub it out with a gray pad (didn't have a white on hand) and the sheen became acceptable. The leveling, however, while acceptable for this project, would not be so (to me, at least) on a horizontal surface like a table or desk top. I've obviously got a ways to go in this respect. BTW, a maroon pad was too much: had to go over that piece with another coat. Tried to pad that on using my favorite technique for wiping on poly, and I don't think I did very well.....I'll see what it looks like in a couple of days.
Conclusions: More work and a slower process than I expected, and the purported ability to ignore drips and overlaps has not proven true. I had runs down the edges (and over onto the opposite side) that I have had to scrape with a razor blade prior to rubbing before they would disappear (or mostly so....) The dry time is nice, one can do the other side of the panel seemingly immediately, but padding the edges is giving me problems....I'm not ready to give up my wipe on poly finish (don't care what some folks say - I love the stuff!), but I'll keep playing with shellac. An aside - finally laid hands on a quart of the unwaxed, and am looking forward to playing with that under poly as well.
Thanks for the input folks. Cheers!
Very nice of you to share the details of your experience. Lots of us are also struggling with mastering the mysteries of the finishing process, and it actually helps to hear specifics about difficulties encountered and how they are ultimately resolved.
I also find that shellac is somewhat less forgiving to slopping than Frenchy experiences. However, his method did get me started using shellac once again, and for that, I thank him.
I also don't find that slopping over a run or uneven overlaps melt those away - instead, I have found that, for me, they require that I scrape and sand them completely away - or - if I don't - that they remain in evidence until I do.
For me, success with shellac includes:- heavily thinned first 2 coats, but carefully applied - slightly thinned remaining coats - being fast but not frantic, - being careful to touch the wet edge with the next strokes, but to not significantly overlap, - to RESIST going back for missed spots (there's a trade name for those, but I forget what it is) until the next coat, - to allow more time for drying between coats than advertised, - and to sand the dickens out of each coat between coats until I start to get a uniform looking film.
I wish I knew of an effective additive that would slow down the almost "flash" drying characteristic of the alcohol base without softening the final finish - - - does anyone out there know of such a thing?
Mike D
Hey Mike,
I agree with every one of your points to suceess, especially the RESIST one, and I'd like to suggest something to you that works very well for me. I pad on the shellac instead of brushing it on.
It takes considerably longer to build up a film but to me it is very forgiving.
I too thank frenchy for getting me to use shellac. Now if I can just get the local hardware store to stock Zinserr dewaxed Seal Coat................... In 23 years they claim to have never heard of dewaxed shellac!
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Hi Bob,
I'm actually experimenting with padding right now, but, so far, I'm not having great success. It's not going badly, mind you, but I'm getting better results using a brush at the present time
I'm not using mineral oil, as I "understand" that this is not necessary unless you are going for french polish - maybe this is a mistake?
The issue that I face is that, when finishing a big panel (say 30" x 24") with brush or pad, I cannot achieve a uniform look using shellac - I get distinctly obvious "zones" across the piece. It takes me a lot of sanding and a lot of coats to overcome this failure in my technique.
The final result is usually great, but Man! it's harder than wiping on Poly!
Mike D
Mike D
You don't need oil to pad shellac. It should take a lot of coats, but it shouldn't take a lot of sanding. My routine is to pad on three coats of 2-lb shellac, about an hour apart, let it dry thoroughly (usually overnight), then sand lightly with P320, just to remove the nits. Repeat as required. (I probably put on a total of nine coats on average, but in reality I don't bother counting; I just repeat the process until I've achieved a good uniform finish without major flaws.) Finally, one last pass with P320 to remove the nits, one pass with P400 to flatten, then rub out with mineral spirits and Abralon pads on my random-orbital sander (for flat surfaces, of course), using 500, 1000 and 2000 grits. (For a glossy finish you'd go one further, to 4000 grit, and maybe polish with automotive rubbing compound.)
And when I say "lightly," I really do mean lightly: The in-between sandings with P320 generally consist of one back-and-forth stroke on each part of the surface. Even the flattening with P400 usually takes less than a half-dozen strokes.
-Steve
Hummm, Sounds like I'm oversanding.
I'll try your approach. Perhaps my problem is that I want each coat to look good before I go onto the next one - paint absolutely requires that, but perhaps shellac does not.
Mike D
Using a brush for shellac allows a faster build than a pad but for me it must be the right brush. I use a flat watercolor wash brush with Taklon gold bristles. These come from art supply stores although http://www.homesteadfinishing.com also sells them. These brushes don't carry a lot of material--little reservoir--but they do let it be applied thinly with zero brush strokes. I typically use 2 lb. cut for brushing, though 1 1/2 lb. cut may be easier to work with in the beginning.
You do need to work quickly, but neatly, going almost entirely in one direction. I start an inch from the edge, either of the wood or of the previously coated area, go quickly toward that edge and then back in the other direction to complete the stroke. This prevents any heavy spot where the brush first touches down. Sounds complicated but it very quickly becomes quite easy.
Missed spots (holidays) should be ignored. Keep overlaps to a minimum but ignore any that do occur. Above all pay attention to the feel. If you feel the brush start to drag or be sticky STOP and let the shellac underneath dry some more before continuing. The holidays and overlaps will mostly "average out", and can be taken care of in the leveling stages.
As with all film finishes other than French polish you do need to "finish the finish" with shellac. Fortunately it sands reasonably well and rubs out superbly. I like to level the shellac by sanding after 3-4 coats using 320 grit. Sanding isn't required for adhesion just to level and eliminate defects. Depending on how much sanding I do to level and remove defects, it may take several 3-4 coat sessions before I do the final rubbing out.
Padding works well too. You should be applying thinner coats with the pad, a smooth surface material--like well washed 100% cotton percale sheeting covering more absorbant material inside. It's not as critical as the pad for French polishing since you will still want to rub out the final surface. The basics are the same as brushing. Move quickly in one direction and lift the pad the instant you feel any drag. Don't let the pad stop on the surface.
" I start an inch from the edge, either of the wood or of the previously coated area, go quickly toward that edge and then back in the other direction to complete the stroke. This prevents any heavy spot where the brush first touches down."
That's an insight I didn't have. I usually put the brush down right against the wet edge, and I have been getting thick spots - actually, I often get thick edges all across the piece.
Thanks, I'll give that a try, too.
Mike D
Mike,
I too wouldn't use mineral oil unless going for a French polish. I only sand the first 2 coats, and VERY LIGHTLY just to remove the fuzzies. Then I don't sand anything until I am near to the final coat(s) and have built a good film.
The other day I tried an experiment as I was having similar issues as you are experiencing. Once I got a decent film all over I used a scrap piece of wood that I wrapped with several layers of worn t-shirt material and used it to pad on the last several coats of 2 lb cut.
Another thing I found helpful was to set up lights and looking at the piece from different low angles you can see where more work is needed. When padding on I try to look at the piece from an angle that highlights the high/low spots.
Hell, if I have a good film established there's no reason why you can't go over the area with a cloth dampened (not soaking wet) with just DNA to aid in smoothing the surface out.
I'll be honest with you and tell you that I am relatively new to this shellac thang but I won't let it get me down. I tend to think that everyone over time developes a technique that works for them but not necessarily for everyone else.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
There are a number of good non-poly varnishes. For a tough finish rivaling poly, consider Waterlox Original or Behlen's Rockhard. Both are phenolic resin varnishes that are hard and durable. Because they are made with phenolic resin, they will be almost a yellow as poly varnishes. For less yellow varnishes, Pratt & Lambert #38, Sherwin Williams are good. McCloskey Heirloom (which is not branded under the Cabot name) is a good also.Howie.........
Thanks,
I've ordered two quarts of the Pratt & Lambert #38. I'll let you guys know how it works out for me.
Mike D
Hey guys
Glad to see that my account has stimulated discussion amongst those of us still wrestling with this.
I too came to the conclusion that starting the stroke a ways from the edge would probably be beneficial. This of course must be rapidly followed by a reverse stroke to complete the coverage.
Also interested in the brush comment. I'll be interested to see how the smaller Purdy reacts to the hardening/softening process if I soak in shellac rather than DNA. Don't really want to have to hunt down (order) a special brush (or set of brushes).
Also figure I'm going to have to get more particular with my padding. A multi ply fold of cloth of the appropriate width is my customary tool for wiping poly, and it rapidly became evident that it wasn't working with the shellac. I'm also going to try letting things dry longer before recoating.
I will tip my cap to Frenchy as well for getting me to give shellac a go. The more weapons in the arsenal, the better the war can be fought.
Carry on Gentlemen!
I'm a novice with this too, and I've had similar problems. I wound up using LV terry cloth pads, sold for staining. The only problem I had with them was a few nibs. To remove them I used a very thin 0.4 scraper blade without a burr held flat against the wood surface. I got that tip from the LV site somewhere. I found that carefully using the edge of the same blade did a pretty good job of removing the edge of shellac overruns without the need for sanding.
I've found this whole thread very useful as I was in the middle of finishing a large piece I was beginning to think I'd never see the end of. Thanks for starting it!
Jim
Howie has it best. Use a traditional resin oil based varnish and you can use any shellac and get easier rub out and a clearer look to boot. If your not planning to walk on these panels you'll not notice any decrease in durability from the tradional resin varnish.
Your other alternative is, as was mentioned, to get the shellac color you want by acquiring dewaxed shellac flakes. The shellac will be fresher as well.
RDNZL,
Why the top coat of Poly?
Is it going outside?
Normally shellac is a great finish for everything indoors.. It's certainly harder than poly. It's more durable than poly, and it can be fixed should something happen to it a lot easier than poly..
Is it the myth about water?
Let me debunk that one.. I had my airconditioner overflow and leave a great big puddle on shellac.. it was there for many hours before I discovered it. I took some towels and wiped up the water and in the morning everything was fine (except the area where the water had been was dust free)
Are you afraid of spilling booze on it? Well booze is not mostly alcohol. Even pure 100 proof booze is 50% water..
Mixed drinks and beer are maybe 5% alcohol.. so once it's really dry shellac can take the occasional spilt drink..
Shellac is harder than polyurethane. Test it yourself..
If you do manage to scratch shellac all you need to do is rub a rag dampened with denatured alcohol across it for a few moments and the scratch disappears.. go ahead test that yourself please..
It's hard to scratch shellac! My 150 pound newfoundland who refuses tio trim his toenails (or let anyone else trim them) can't scratch it. Just now after walking on the floor for well over a year in dirty work boots etc. can I see any sign at all of any scratches.. (which took me maybe two whole minutes to repair)
It sounds like you are over thinking this.. Unless of course you intend to bring it outside.. You should know that I used a layer of Bullseye shellac under my three coats of spar varnish for outside work. The spar varnish is sticking well nearly 5 years later..
Hey guys
Sorry I took so long getting back. Been busy, both with the project and with other distractions - I'm a New Englander, and there's this football team chasing immortality....
Anyways - thanks for the input. Tomorrow being Monday, I'm going to check out what the local store has in the way of varnish, and might go that route. Or I might skip the shellac and just go poly all the way. OR - I might just do a Frenchy and do a shellac only. We shall see.
BTW, the biggest reason I lean (or have always leant) towards poly is that I personally like a satin, or even flat finish, and without rubbing things out, poly seems to be the fastest way to achieve same. I have had good results with a highly thinned first coat, a more viscous second coat, followed by a final coat of wipe on. I sand between 1st and 2nd w/ 220 and tack.
I began experimenting with shellac for two primary reasons: 1. It dries so much faster and 2. the aging effect of a wash coat of amber.
In my experimental efforts, I found the final sheen of straight shellac after several coats to be glossier than I like, thus my thought process on the current project: how to most easily achieve a satin/flat effect over "aged" white maple.
As I do not generally produce fine furniture, the obscuring effects of the emulsifiers in satin poly have not yet bothered me, but in time that may change.....
One other point of note - most of my work at this point is just that: projects for my employer. As such, I am somewhat limited in obtaining supplies. Their first preference is to obtain things locally, and if necessary, to use a distant supplier who will allow us to buy on account. Some of the supplies/tools suggested in various posts are available to me only via credit card and it is like pulling teeth to get to use the company credit card - I know - been there, done that. With success, mind you, but the process leaves one looking for any other alternative.
Anyways, thanks for the input. The search for the ultimate finish and finishing process continues. We live and (hopefully) learn.
'Till next time - I'll be lurking about, and occasionally submitting my .02 worth.
RDNZL
RDNZL,
If you want to take a little gloss off the shellac while it's dry but before it cures completely take a piece of 4000 grit sand paper to it. Then don't buff it out..
One more to go. Go Pats!
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
........"We have reached our rendevous with destiny"........
I use dyes in shellac all the time. Liquid formulations. It's not time consuming. Set aside your amount of shellac (what you think you'll need), put a little bit of dye in, test it on scrap, repeat. I can get the color I want in under five minutes.
This forum post is now archived. Commenting has been disabled