Replies

1. 
   SteveSchoene | Nov 01, 2010 03:48pm | #1

   No it's not a myth,but it isn't necessarily something that appears in short order.  You may not discover problems with adhesion for quite some time--long enough down the road that you may not asspciate it with waxed or dewaxed shellac, but just have some more chipping of the varnish that might have not happened if the shellac were not dewaxed.  So you can appear to get away with it. 

   Of course, there is amber shellac that is dewaxed sold in flakes. You may see in called orange shellac--that's the commodity name in the trade, and Zinsser marketed orange and white shellac, which products are now amber and clear as being more understandable. 

   Since it only takes a bit moreeffort to be sure that you have it right, that's certainly what I would continue to recommend. 

1. 
   a_e_b | Nov 02, 2010 01:31am | #2

   Poly over amber...

   I'll look for the amber shellac in dewaxed form then.  I don't mind mixing my up my own batch of shellac from flakes at all.

     Also, good tip on Zinsser and their product naming.

   Thanks for clearing that up Steve.

   AB

2. 
   GretchenTHE FIRST | Nov 02, 2010 11:22am | #3

   I haven't read the article, but what about just using a non-poly varnish. Could be even prettier/better..

2. 
   SteveSchoene | Nov 02, 2010 10:46pm | #4

   Good point, Gretchen and Howie.  I should have mentioned that.  No need for "poly" on furniture since non'-poly varnishes are superior in essentially all respects except resistance to heavy abrasion like you get on floors. 

3. 
   NRHiller | Nov 05, 2010 08:43am | #5

   Oil-based polyurethane over amber shellac

   I happened upon this discussion during a web search last night and thought I should contribute. The fact in this case--basic rules notwithstanding--is that you can apply oil-based polyurethane over amber shellac (including Zinsser's Bulls Eye) and expect to have a durable finish free of problems. The key is in the process, as described in my article and summarized here:

   It is critical to apply the shellac in a thin coat, allow it to dry (I usually allow at least overnight), and then scuff sand it meticulously with 220- or 320-grit paper to provide a key for further coats of finish. After scuff sanding, remove every bit of dust with a shop cloth lightly moistened with mineral spirits and allow any residue to evaporate. Apply the oil-based polyurethane (I usually use Minwax satin for this finishing technique) in two or three thin coats, allowing each coat to dry, then scuff sanding and removing dust, as before.

   Does this technique break the rule about applying poly over a shellac that has not been dewaxed? Yes. But I have been using this technique (on tables, sideboards, nightstands, kitchen cabinetry, and other pieces subjected to real use) for almost fifteen years and have never had a complaint from a client. Nor have I ever experienced problems with adhesion on pieces finished this way for my own use. I cannot speak to likely outcomes if you use other brands or types of finishing products, and I see no reason to use water-based poly over amber shellac, as my experience has invariably been that the water-based poly will give an ashen look, which is directly opposite to the entire point of using the technique described in the article.

   I hope this helps!

1. 
   SteveSchoene | Nov 05, 2010 03:29pm | #6

   Yes, if properly keyed to the surface, you may get the polyurethane varnish to adhere, but why? 

   First, there isn't really any purpose for the polyuethane additive on furniture other than it is inexpensive.  Superior finishes can result from non-poly varnishes which are harder, and much easier to rub out to the desired sheen if needed.  These are also more repairable. The additional abrasion resistance is relevant on floors, but not really meaningful on furniture.   With three brushed on coats, you may be able to detect the subtle lack of clarity with polyuethane.  You wouldn't likely notice this without direct side-by-side comparison but it is there.  The Minwax poly is, I believe formulated around linseed oil suggesting it will yellow more significantly over time than varnishes based on either soya oil or tung oil. 

   And, even if polyuethane varnish is used, amber shellac is available without wax, only not mixed in a can.   It's often hard to find cans that are really fresh, especially since you never know how it has been stored before it reached the retailer's shelf. 

   So it is not so much that the finish in the article is bad, but that there are improvements possible that don't make the process one bit more difficult to accomplish, other than needing a little foresight in obtaining materials that aren't available at the nearest big box store.  And, by following the basics, it wouldn't be necessary to add the proviso suggested that using other brands of finishing materials might not work as well.  Any of the oil based varnishes, with or without poly, will adhere to dewaxed shellac. 

1. 
   Gretchen | Nov 05, 2010 05:33pm | #7

   JUst SO much easier and better to use non-poly. Where did we go so wrong that everything has to be poly.