100g of Paraloid B-72 and 1l of Acetone ready for you to mix at home to your desired concentration.

You’ll probably have heard about weight-by-vol% solutions – and this is enough to give anyone who hasn’t done Chemistry since they were 15 the collywobbles. Fear not! It’s not as tricky as it sounds to get the right concentration of solution for the job. A 10% wt/vol solution is the same as 10g of Paraloid B-72 for every 100ml of solution. This should not be confused with 10g of Paraloid added to every 100ml of solvent (this is a weight-by-weight solution).

This can make the brain hurt a bit, but there are two ways to approach the measurements.

1. Weight-by-weight solutions: Calculate your proportions w/w. E.g. 10g of Paraloid in 100ml of Acetone is a 10% w/w solution. You might need to experiment as most of the recommendations you’ll find online pertain to w/vol% solutions (or perhaps w/w solutions that the author believes to be a w/vol solution – you can see it is a bit of a wormhole). There is no problem doing it this way if you find it easier – just be consistent with yourself and make sure you write on the bottle the concentration.

2. Weight-by-volume solutions: Most recommendations are expressed as weight by volume and so you’re more likely to get the results you’re after by following this method. You can make up a solution with a set amount of Paraloid and dilute it to the concentration you require once the pellets have dissolved in the solvent.

Learn more about using and mixing Paraloid B72 in our comprehensive guide

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