Hi Line,
apologies for the slightly slow response to what is a very good question!
If the coffee you collect is too dry, then there are a couple different ways you could add moisture to it, but it depends a bit on how dry they already are.
1) easiest method (if they are only a little too dry): mix in a bit more well hydrated straw or sawdust pellets
– if the coffee is only a little too dry, then adding 20-30% well hydrated straw or pellets should help to balance out the moisture content.
– Coffee grounds are usually at maximum hydration at around 55-60% (this is the amount they can hold before they become saturated).
– Sawdust (depending on particle size) saturates at around 60-65%
– Straw saturates at around 72%
– So by adding a bit more straw or sawdust at higher moisture content, it will balance out the overall substrate moisture levels
2) less easy method (if they are very dry): add a measure amount of boiling water to the grounds to hydrate them to target moisture level
– if the coffee is very dry, then you can add more moisture by pouring and mixing in some boiling water to raise moisture levels
– follow these steps to find out what the moisture content is of the coffee you are collecting:
1) Weigh sample of 100g coffee
2) Dry sample fully in an oven for 1hr at 180C (350F) and weigh again
3) Moisture content = difference between wet and dry weight of the sample
e.g. if 100g of your fresh coffee sample coffee weighs 60g after being dried; then original moisture content of the coffee was 40%
– Then add the right amount of extra boiling water to bring the coffee up to 55% moisture content
Soaking the coffee in water then draining it doesn’t tend to work very well as you end up with a really wet over-saturated set of coffee grounds that are hard to grow with unless you then press the excess moisture back out with a wine/cheese/apple press.
Hope that all makes sense – just ask if anything is unclear 🙂
best wishes,
Adam
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