Like
DougE
and
indaswamp
said. Very easy to do for dry rub. This is 1 of 2 reasons why I like equilibrium cure best, the fact you can precisely target, hit, and replicate exact salt levels. The 2nd reason is why I pretty much HAVE to use it vs. Gradient brines: you can let it go 5 or 10 days long and it will never get saltier than your planned total. I go on trips away from home sometimes 5 days, so I can't oversalt and pull the meat at the exact right time for correct saltiness. (that method is faster due to higher salt concentrations, but timing is key and my work can't support it).
If you're intested in equilibrium brining, go read genuineideas.com and diggingdogfarm.com for nice calculators and info.
----extra info on other exact salt method---
You can also pump inject an exact weight of cure/brine into meat, usually 10% meat weight is used as meat will hold that. Then you calculate the correct amount of salt and sugar and cure#1 to be in that water...it is a much more complex and unforgiving method as the brine and cure is so strong, accurate weight before and after must be adhered to. Here is an example:
1kg meat. 10% pump is 100g water. Total cure is calculated only for the meat, not meat plus water, so for bacon 1.9g. Say 2% salt, again we will use just meat as we expect the 10% water to be evaporated during smoking, 20g. And 2% sugar, 20g. Fast pumped bacon like this must also have sodium erythorbate in it to convert nitrites fast since it is made, smoked and to market in a day. Mix salt, sugar, cure, and erythorbate in boiled water, let cool. Inject it to meat, weigh meat before at 1kg and after to ensure 1.14kg (water plus the 42g salt/sugar/cure). There is a limit for salt in solution, think its 26% so we're getting close. Usually extra brine at same ratio is made, then you just pump right amount and no extra into meat. They actually make brine perfectly so 100g has correct amounts, not my examples 142g, but you can see that is even more hard calculations. Marianski's books detail it, but you can see it's not as easy though it is extremely fast and exact, so most commercial bacon is made this way. Disclaimer, I don't do fast pumped so calcs might be slightly off but you get idea, book reading required on this method. But calcs are for the nitrite really, nothing stops you from adding extra salt on outside of this method.
---gradient method, lots of salt plus timing--
Nothing wrong with this and works great and fast, IF you can be disciplined about curing meat exact same time always. You'll easily be able to then decide how to tweak salt next time. There is a minimum cure penetration time, then after that it's just getting saltier til the saltiness time you like. Usually a dry rub in a salt box or similar. 2nd fastest method. Just not time-forgiving or accurate enough for my needs.