Shellac as Sealer and Final finish

[mrsamimi]

Hello Everyone, 

 

I am learning from multiple forums here that Shellac is a perfect sealer/finish for almost all surfaces. I am building OCcre Santisima and the hull is Sapelli wood and love the natural color of it so I am going to apply 2-3 coats of clear Shellack and sand in between.

 

My only concern is, I am hearting Shellac has durability issues compared to varnish, like exposure to heat and moisture but wondering for a model ship, we dont out them next to humid areas or extreme heat anyways! Any advice/feedback/experience on Shellac durability issues?

 

Thanks in advance!

[Snug Harbor Johnny]

  I favor shellac in many applications for wood, as shellac has been a proven wood finish for hundreds of years.  Varnish can be durable as well, but can be subject to 'crackling' over time if applied too thick.  Models (and electronics) should be kept in an environment that a human is comfortable in.  Too much heat (as in an attic) can be ruinous.  Cold is not as much of a problem, but accumulation of dust should be avoided - and there are a few ways of doing that, either on display or in storage.

[mikiek]

Just be careful. Shellac and Varnish can be mentioned in posts but can also be very generic terms. Many types of shellac, many types of varnish.

 

Whatever you think you want to use, always try it on some scraps of the material you ultimately want to cover. Your decision at that point should be easy.

[paul ron]

whethere you use varnish and/or shellac, keep in mind its a static model, not furniture thats exposed to usage and needs a protective finish. our ships get a nice finish to look pretty.

 

imho, I'd use one or the other, not both. shellac is alcohol based, varnish is oil based (or water based).. each has a different hardness when cured. the different types can present separation as it ages with expansion and contraction of the wood due to seasonal humidity changes and the difference between how each finish reacts to it.

 

the first thined coat of whatever you use is the "sealer" coat. it penetrates the very surface of the wood to help keep grain from raising and sealing the softer part of wood so it wont soak more than the harder parts in the grain... this will help give an even finish coat. you'll lightly sand between the sealer and finish coat to ultimately allow the final coat to self level evenly.

 

 

Edited February 12 by paul ron

[wefalck]

Not sure, why people differetiate between shellac and 'varnish'. Shellac can be used as a varnish among other applications.

 

A varnish consists of some material that form a continuous coating, e.g. a resin or a oxidising oil, and a solvent that allows to apply this material and vaporises after application.

[paul ron]

well the term of finishing, "varnishing" or "shellaking," has changed over the years and became synonymous although they are chemically different.

 

shellac is a natural excretion of a bug, varnish is made of other resins and has also evolved to polyurethane made of polymers refered to also as varnish. maybe this link can describe the differences.... 

 

https://www.hgtv.com/how-to/home-improvement/what-s-the-difference-between-polyurethane--varnish--shellac-and

 

regardless of what you use, id rather not mix finishes.

 

[wefalck]

The problem is that people confuse 'materials' with 'applications'. A lot of materials can be used for the same application and a lot materials can be used for different applications.

 

Shellac can be used as a cement, as a varnish, as a binder in paints (with pigments added), as sanding sealer (with pumice added), for seals, etc. etc. 

 

I fully agree and have repeatedly said so in this forum, that mixing varnish- and paint-systems can lead to trouble unless you really know what you are doing.

[François de Saint Nazaire]

In France we use Wood filler ( call Fondur) it is an impregnation that penetrates the pores of the wood and follows its dilatory movements. Therefore, it does not crack. The final appearance is a soft satin. Depending on your needs or preferences, you can leave it as is or cover it with a wax or shellac finish

[wefalck]

Again 'fonds dur' is an application, that can be achieved with a variety of materials, such as shellac plus pumice (the basis of classical 'French Polish'), nitrocellulose plus pumice, acrylics plus something as filler etc.

[Slowhand]

I saw a very nice planked deck of the OcCre Albatross. Can’t find the post now. The lime planks had been finished with Shellac and the slightly different grain on different planks had been high-lighted . Buying Shellac flakes, orangey ones in particular is quite easy but the methylated spirits is more difficult, much of it has blue dye added. Then I read that ‘sanding sealer’ which you can buy in UK has the same purpose and can be used to French polish. In fact I have some in my shed😊😊. I wonder if they are the same or is it worth making the effort to make my own Shellac?

[paul ron]

the denatured alcohol from home depot paint section is clear.

 

rubbing alcohol i see has a blue tint.

[RossR]

I use denatured alcohol from the hardware store with good results.  If you live somewhere where Everclear (180 proof grain alcohol) is legally sold, that would probably be the best option.  No additives would be present to prevent human consumption, just 90% alcohol.  In Minnesota where I live it is not legally sold.    

[Slowhand]

Thinking about this IPA isopropyl alcohol is readily available as Tamiya acrylic paint thinner, I imagine it’s ability to dissolve shellac flakes is the same as meths, it’s an alcohol after all (X-OH).

[Snug Harbor Johnny]

  On 3/25/2025 at 9:34 PM, Slowhand said:

Thinking about this IPA isopropyl alcohol is readily available as Tamiya acrylic paint thinner, I imagine it’s ability to dissolve shellac flakes is the same as meths, it’s an alcohol after all (X-OH).

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  I've tried that and it doesn't work.  For one thing, the water content in 'Rubbing alcohol' complicates things (70% or 90% IPA is whats readily available).  Its also a 'different sort' of alcohol that doesn't work like 'denatured' alcohol (methanol).  Pure (lab grade) ethanol can work, but the highest concentration you can get (with paying a lot from a lab supply) is 95% (190 proof) Everclear from a liquor store.  I tried that as a solvent for shellac flakes, and the water content still affects the liquid product negatively.

[Slowhand]

Thanks that’s really useful saved me some time and expense. In the UK you used to be able to buy absolute alcohol 100% when I was working but you needed a Home Office License so that’s out. Liberon sell Shellac in different colours so I may try a light one.

[wefalck]

We had this discussion in another thread already. Don't mess around with other solvents. Alcohol is the normal solvent for shellac and the cheapest alcohol you can get is normally denatured alcohol. It's being sold under various denominations and depending on country in supermarkets or hardware stores. There should not be a problem in finding it even in alcohol restrictive areas of the world.

 

Shellac solution is not the same as sanding sealer. The latter normaly contains 'fillers', typically either pumice or some sort of clay. The fillers serve to fill the pores of the wood. The 'binders' in sanding sealers can be shellac, some nitrocellulose solution, or more recently also metacrylic acid solutions.

 

So, shellac on its own is a varnish, rather than a sanding sealer. However, on hard woods no filling may be required, so that pure shellac can form the basis for building up a varnished surface.

 

However, you don't want 'varnished' decks normally. Therefore, it is a good idea to rub down the wood treated with sanding sealer or neat shellac using fine steel-wool. This results in a smooth surface with a satin finish, but without an obvious layer of varnish.

 

[RossR]

  On 3/26/2025 at 3:44 PM, wefalck said:

Therefore, it is a good idea to rub down the wood treated with sanding sealer or neat shellac using fine steel-wool. This results in a smooth surface with a satin finish, but without an obvious layer of varnish.

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I love the result with steel wool, but hate the mess.   I have tried other products like various grades of sand paper, and various brands and grades of “Scotchbrite” type products and the result is never as good as with steel wool.   
 

Has anyone found something less messy that produces a result like steel wool?

 

[Slowhand]

Well,  any denatured alcohol you buy in the UK is coloured with Methylene Blue so not much use for craftwork.

[paul ron]

  On 3/26/2025 at 4:15 PM, RossR said:

I love the result with steel wool, but hate the mess.   I have tried other products like various grades of sand paper, and various brands and grades of “Scotchbrite” type products and the result is never as good as with steel wool.   
 

Has anyone found something less messy that produces a result like steel wool?

 

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yes wet dry sand paper.... it comes in grits as fine as 5000 silicon carbide. you can also get fine papers at auto stores.

https://www.amazon.com/LotFancy-Sandpaper-Assortment-Automotive-Polishing/dp/B08J46MW33/ref=asc_df_B08J46MW33?tag=bingshoppinga-20&linkCode=df0&hvadid=80814196410705&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=m&hvlocint=&hvlocphy=&hvtargid=pla-4584413763136221&psc=1