what will the door or picnic table be made out of ?

 

Wood

It’s a purely hypothetical question. For sake of argument, let’s say fir or pine.

 

Its ok.

 

If you are going to coat it with several coats of spar varnish, you wont need shellac.

 

Using shellac as a sealer followed by spar varnish for a durable and protective finish on doors or picnic tables is a good approach. The shellac offers excellent sealing properties, and the spar varnish provides the necessary protection against outdoor elements. Ensure proper application and compatibility to achieve the best results. For a more detailed review look here https://www.woodmagazine.com/woodwo...orking-how-to/finishes-finishing/shellac-a-classic-finish-for-todays-woodworker.

 

Yes and no whether it could be used or not. The spar varnish really needs to penetrate into the wood and if you seal it with shellac it would prevent that. It would work but you would shorten the duty life of the spar by doing so. Usually it's a good idea to thin the first coat of a spar so it gets deeper penetration.

 

I dont understand the modern fascination with shellac as a finishing product. It is by far the least protective of any of the modern finishes. It has fallen out of favor as a commercial finish shortly after WWI and that was over 100 years ago. It does have some commercial value in home grade lumber in that it can be used over some of the stickier sap blemishes in construction grade lumber prior to painting and also I believe it is used in the candy coating of M&M's.
I'm thinking I just created a firestorm.

 

and also I believe it is used in the candy coating of M&M's.
I'm thinking I just created a firestorm.

... You did.

Last Fall (2023) I made the mistake of informing my spouse that the red coloring in Good 'n' Plenty comes from insects. I noticed that she only recently started to eat the pink ones again. I did not comment. Now @Tony B has leaked another "sausage making" secret about M&Ms (and other candies and foods).

Do people know that shellac comes from insects, too?

 

One of the reasons I was asking is because for woods like walnut and mahogany, garnet shellac has a look that I’ve not matched with other products. Garnet shellac can also make new stuff look old. Also, shellac is easily tinted with TransTint dye where varnish is not.

Although shellac isn’t a fragile as many have been led to believe, there are circumstances where it is prudent to put something more durable on top of it; thus my question about outdoor use and so the question about top coating with spar varnish which unfortunately sounds ill advised.

I hope I’m not jinxing myself here, but I have a handrail, a banjo and a guitar finished with shellac. None show any signs of wear and if they do, they’re easily repaired. Of course, none of these things is exposed to water or alcohol.

One of my favorite finishes is just a few coats of shellac, polished with 0000 steel wool and wax. There’s something about the look and feel that’s really appealing to me.

I don’t have proof, but I swear that shellac mixed from flakes dries harder than the canned stuff.

 

And now we will become better citizens for knowing this.
Gotta love this forum.

 

Technically you can add an aniline die to a varnish to recreate the effects of amber shellac. I know it would be alright for inside work, I just don't know how it would affect the duty life of an exterior finish. You might try it and stick it out in the direct sun for the summer and see what affects it has. The color could also fade to clear. Aniline dyes are prone to fade.

 

Aniline dyes are prone to fade.

All dyes and stains fade in sunlight; water-soluble aniline dye fades slower than alcohol or oil based.

 

If all dyes and stains disappear in a couple of months in direct sunlight , are they also affected by LED's and fluorescents?

 

Some stains like minwax are prone to fade but certainly more colorfast than a aniline dye. I haven't noticed any measurable fading with any other brand stain. I've added cabinets to a kitchen before using varathane stain many years after the initial job and they matched. Outdoor finishing is a lot different story though. An aniline dye would fade under artificial lighting but at a much slower rate than outdoors. What was discussed is suspending the dye in the finish which makes it more susceptible to fading.

 

Shellac isn’t suitable as an exterior sealer no matter what the top coat is due to shellac films having an elongation at break value of 3-4% which suggests it will crack, craze, and pull apart beneath the varnish, if substrate expansion & contraction exceeds 3% due to changes in moisture content.

 

This is getting complicated and should be a very simple question. First off, I would stick to all the finishing products be manufactured by the same company. Their customer service would be invaluable. If you mix different manufacturers products, none of those manufacturers will help you in case the finish fails.
If you are planning on using a good spar varnish (definitely not Minwax Helmsman) that should be all you need after staining. Its a very simple process. If it is going to be outdoors, they will recommend approximately 6 - 8 coats - the sun is very harsh and very unforgiving.