What Is a Cut of Shellac?
A cut is how much shellac is dissolved in a given volume of alcohol, written as pounds of flakes per US gallon. A 2-lb cut means two pounds of shellac flakes dissolved in one gallon of alcohol. The 2-lb cut is the all-purpose brushing strength. The 1-lb cut is for sealing and washcoats. The 3-lb cut builds body faster.
Once you know how the number works, you can mix or thin any cut with a scale and a measuring cup. The pound cut chart is the full table; the short version is below.
The three common cuts
| Cut | Flakes per US gallon | Flakes per quart | Typical use |
|---|---|---|---|
| 1-lb | 1 lb (454 g) | 4 oz (113 g) | Sealing coats and washcoats |
| 2-lb | 2 lb (907 g) | 8 oz (227 g) | All-purpose brushing and general finishing |
| 3-lb | 3 lb (1.36 kg) | 12 oz (340 g) | Heavier coats where you want to build body quickly |
Small-batch conversions
Weigh the flakes and measure the alcohol. The same cuts at jar sizes:
| Cut | Flakes : alcohol (oz : fl oz) | Metric (g : ml) |
|---|---|---|
| 1-lb | 1 : 8 | 28 g : 237 ml |
| 2-lb | 1 : 4 | 28 g : 118 ml |
| 2-lb | 2 : 8 | 57 g : 237 ml |
| 3-lb | 1 : 2 2/3 | 28 g : 79 ml |
| 3-lb | 3 : 8 | 85 g : 237 ml |
A metric shortcut that works at any size: a 1-lb cut is about 12 g of flakes per 100 ml of alcohol, a 2-lb cut about 24 g, and a 3-lb cut about 36 g.
How to mix to a cut
Measure the alcohol first, weigh the flakes, and dissolve them as described in How to Mix Shellac Flakes. Glass or HDPE, tight lid, 24 to 48 hours. Label every batch with its cut the day you mix it.
How to thin a cut down
Thinning means adding alcohol to a mix that is stronger than you want. The formula, which is a close approximation:
Alcohol to add ≈ current volume × (current cut ÷ target cut − 1)
- Measure the volume of the mix you have.
- Divide the current cut by the cut you want, then subtract 1.
- Multiply that by the current volume. That is the alcohol to add.
- Add it, stir well, and let it stand an hour before use.
Two examples. A quart (946 ml) of 2-lb cut becomes 1-lb with 946 ml of alcohol added. A quart of 3-lb cut becomes 2-lb with 473 ml (half a quart) added.
Thinning assumes you know the cut you started with. A jar that has been open or loosely capped has lost some alcohol, so its real cut is a bit higher than the label. Measure what's in the jar and thin from there; if you have no idea what it is, remixing is quicker than guessing.
If the mix isn't behaving
- Too thick to brush cleanly: the cut is high, or the mix has lost alcohol. Thin it.
- Too thin to build a film: too much alcohol. Dissolve more flakes, or remix at the cut you want.
- An older jar: test it with a drop on glass before deciding anything. Thinning changes the cut, not the age. See How Long Does Mixed Shellac Last?
FAQ
Is a 2-lb cut the right default?
For most brushing and general finishing, yes. Use a 1-lb cut for sealing and washcoats, and a 3-lb cut when you need a heavier coat.
Can I use a metric cut?
Yes. 24 g of flakes per 100 ml of alcohol is a 2-lb cut, and the ratio works at any size.
Does the type of alcohol change the cut?
No; the cut is a flake-to-alcohol ratio. Use the same alcohol to thin a mix as you used to make it. See What Alcohol Do You Mix Shellac With?
Does dewaxed or wax-in flake change the cut?
No. The ratio is the same for both.
How do I know which cut my mix is?
Label every batch with its cut when you mix it. An unlabeled jar can only be estimated.
All the guides are collected at Shellac Guides. Flakes by grade: dewaxed, wax-in, and button lac.