All type of candle dyes are concentrated but liquid dye is more concentrated that the rest. For using liquid dyes, one would only need a few drops, depending on the shade of colour you want. This is why they come in droppers. Note that there can be other types of liquid dyes used for other purposes. But you must only search for and buy ones that are specially meant for candle making.
For using them, you need to determine how much wax you want to work with. This in turn determines the amount of dye you need. Digital scales can be used to measure your wax. You may not be able to purchase the exact shade of colour that you want. But the advantage with liquid dyes is that you can achieve the shade you want by adding more or less drops.
Also, when making a large number of candles of the same colour, consistency can easily be achieved with liquid candle dyes. This is because you can just use the same drops for each candle. This is not the case with other types, especially powder dyes. Also liquid dyes work in many types of waxes from the popular paraffin wax to natural waxes such as soy and palm wax. Usually, they produce lighter shades when used with soy wax.
Another advantage liquid dyes have is that you can easily mix two colours together. All these advantages make them the most popular of the other types and they are easy to use as well. Just add desired drops when the candle wax reaches required temperature before you pour the wax.
How to Measure Your Liquid Dyes
I have mentioned that the amount you use determines how light or dark the colour would be and also that you need very little. You would only need about 0.005% to 0.15% of dye concentration. Anything less would give you a colour close to white. And anything more would affect your candles negatively.
You might wonder how you would measure the percentage since they are liquid. It is simple. Remember I said the weight of the wax is important? Measure the weight in grams and multiply by the percentage that suits you. The result should be the amount of dye you need in milliliters. This means you would need about 0.05 to 1.5ml per kilogram of wax, which is roughly 2 to 50 drops, depending on how much you want. Pretty easy?
Be careful when using liquid dyes though. Spilling them can be really messy. To avoid spills, seal your dropper (or whatever it is in) when not in use. Also, liquid dyes have a foul odour. Do not worry. This does not affect the smell of the candle in anyway, especially not if you are adding scent oils.