Tim Connell. The shellac will stick to the poly just fine, shellac will stick to almost anything. The problem is, poly is a rather soft/flexible material, while the shellac is hard/inflexible. As the poly moves the rigid shellac on top can’t move as much and will crack over time.
Can shellac be applied over varnish?
From Paul Snyder, forum technical advisor: You can apply oil-base varnish (non-poly) over shellac without any problem. And it doesn’t matter if the shellac contains wax or not. The combination of a coat of shellac followed by a few coats of oil-base varnish will produce an attractive and durable natural finish.
Which is better polyurethane or shellac?
It goes on clear without adding a slight color that oil-based versions can, and it dries much faster. As with shellac, water-based polyurethane won’t hold up well to heat and chemicals. It’s good for bookcases, desks, side tables and picture frames — anything that won’t be exposed to extremes.
Can you put shellac over spar urethane?
If the spar varnish/BLO mixture is used sparingly (i.e. don’t go for a big build with it) then it should be ok with the shellac on top. I just forgo all of that and apply shellac directly.
Does shellac resist water?
Shellac, just as many other finishes, is not waterproof, however, it is quite water resistant. Shellac can easily withstand water for about 4 hours. Even if the surface is not wiped, the resulting faint white stain will still fade away as it dries. However, repairing shellac is extremely easy!
How durable is a shellac finish?
Shellac is very beautiful and forms a reasonably durable finish that can be high gloss in nature. It does have drawbacks however. If you place a hot mug or a hot pan onto a shellac finish, a white ring can develop under it. It is also soluble in alcohol.
What finish goes over shellac?
But with that quick step on and off of my soapbox, I will say that even the company recommends that you do not use a polyurethane over shellac, but many woodworkers do this on a daily basis without any concerns. It is, however, OK to use an oil-based urethane over shellac.
What is the difference between shellac and varnish?
Shellac is merely a resin that is secreted by the lac bug. It can be processed and then sold as dry flakes. It can then be used as a brush-on colorant and most commonly as wood finish. Varnish, on the other hand, is a protective finish or film that is very hard and is also used in wood finishing.
How do I protect my shellac finish?
Pour some denatured alcohol into a small can or plastic bucket. Buy a natural bristled brush rated for oil paints and finishes. Dip the brush into the alcohol and allow most of the alcohol drip out of the bristles. Brush the remaining alcohol over the shellac surface.
Which is harder shellac or polyurethane?
As explained above, polyurethane is a curing finish. It hardens in two phases, creating an extra-strong and durable protective layer over wood. Shellac is non-curing. Once it dries, it is as hard as it will ever get.
Are shellac and polyurethane the same thing?
Shellac: A natural finish derived from the lac bug, it imparts a warm tone and adds depth to grain. (Drying time: 30 mins) Polyurethane: A synthetic finish made from plastic resin and available in water- or oil-based forms.
Does shellac make wood shiny?
Shellac: This finish is virtually a natural product that creates a lustrous, mid-gloss sheen with a golden tint.
What is dewaxed shellac?
Dewaxed shellac is an ideal sanding sealer. It bonds tenaciously to virtually any bare wood or finished surface; it dries very quickly, sands smooth with the greatest of ease, and since it contains no stearates it provides a reliable base for any kind of finish going on top.
Can you put shellac over lacquer?
Shellac over lacquer should be fine. The shellac is thinned with alcohol and the lacquer with lacquer thinner (usually a combo including acetone, MEK or MIK, etc), The alcohol should not dissolve the lacquer.
Can you spray shellac?
Shellac should be sprayed in a warm atmosphere and each coat takes only a few minutes to dry. In an hour a piece can be ready for delivery. I use an Earlex 5500 HVLP sprayer. It’s one of the least expensive but for my level of production it works perfectly.
Do you need to seal shellac?
The problem with shellac, and part of the reason why it has fallen out of fashion as a modern wood finish, is that when used alone it is easily damaged by water and alcohol. To produce a lasting shellac finish, a transparent sealant must be put on top.
Can you put polyurethane over Zinsser shellac?
Yes, you can poly over shellac. The final coat(s) of shellac needs to be a dewaxed shellac, so you would have to clean yours and then put down another coat or two of dewaxed shellac. Zinsser’s Bulls Eye has a great color, but it also has wax.
Do you sand between coats of shellac?
You do not need to sand between shellac coats, but it can seriously improve the piece’s finish. That is because small imperfections like specks of dust get bigger and bigger every time you add a new coat. Shellac will bond with the coat under it, making one layer. Not sanding can leave you with a lumpy finish.
