Consider running to test to determine what value of black can be seen as different from the maximum black your particular printer produces, with your inks, your designated ppi and on your choice of paper. Any one of those variables may affect the outcome,
Construct a test form similar to the one shown above: a series of 1” boxes. Note that the patch marked 100% and the patch marked Spotter are the same value.
Print the chart, let it dry, then cut out the Spotter and punch hole in it. Lay the Spotter over each of the other patches and determine at what value of patch you see a difference you find acceptable. Let’s say that value is 85%. That tells you that the darkest part of your type must be no darker than 85% no matter how it looks on you monitor..