What is Shellac you ask? Well it actually comes from the excretions of the Lac bug. The female bug, which lives in a variety of trees in India and Southern Asia, consumes and processes tree resin. As the bugs process the tree resin, they form tube like trails behind them on the outside of the tree bark.
These are the raw form of Shellac, which is actually a natural polymer. These trails are gathered and processed using heat, to liquefy and filter bark and impurities out of the resin. It’s then spread in sheets to cool and turned into flakes or pellets.
The types of trees the Lac bug is eating can affect the colour of the shellac, ranging from almost clear, called Blond Dewaxed to amber/orange, called Straight which is the most common or reddish colour called Button Lac and a deep red called Garnet Lac.
Readymade Shellac can have many additives that are used for various purposes like extending the shelf life. When you know how to mix your own, you can make smaller batches as needed.
Excess Shellac mixture can usually be stored for up to 3 months.
Real Shellac is edible and safe to consume, which makes it perfect for contact with food without concern for toxicity.
Just mix up a cup or two at a time.
Shellac can be made thin or thick depending on your requirements. I generally like a thinner mix. I find it soaks into the wood better. Then I apply subsequent coats until I reach the level of sheen I want. It also dries almost straight away as the spirits quickly evaporate.
Mixing Your Shellac Flakes
Grab yourself a clean glass jar with a lid. The following measurements will give you a fairly thin mixture. You can adjust it as you wish from there.
Measure approx. 28grams of flakes (1oz) and add 236ml (8 fl oz) of good quality Methylated Spirits or 190 proof denatured absolute alcohol if you can get it which is said to dry quicker and harder.
Mix the two together in the jar and leave for a few hours or overnight to break down and liquefy. Before you use it the following day, it is a good idea to strain through a paint filter or similar to remove any rubbish or foreign objects like bark or insect parts.
Thicker versions of Shellac cuts have corresponding higher amounts of dry Shellac Flakes. Higher cut rates will result in thicker Shellac that takes a bit longer to dry. You can see other mixture rates in the tables below.
You will hear people talk of a 1 pound cut or 4 pound cut etc. This refers to the amount of flakes to DAA used to create the thickness of the Shellac. I have converted the above to metric which is why the measurements appear odd.
You can also use Shellac as a blocking agent for stains etc. Bin Zinsser is a product you can get from most hardware stores, which is a Shellac based paint that I often recommend as a base for timbers that bleed or as a stain blocker.
It is especially good if you want to paint dark coloured timber in a light colour, as it is a white based paint. It is not always easy to work with due to its quick drying time, so have a practice to reduce brush strokes and perfect your technique before you do your main piece.
If you don’t need that bonus white paint base, mixing up your own shellac is both cheaper and less toxic. (Bin is quite fumy). You can always use this and then paint a coat of Fusion Sterling over the top to cut out the deep timber colour before you paint your chosen lighter colour.
Keep your raw Shellac flakes in the fridge and they will last for years.
I found this Shellac Mixing Chart Conversion at woodnewsonline.com