Normal liquid acid is not concentrated enough to lay blotter with, apparently, so that adds to greenmeanies' point. You could not get the paper to absorb enough to get a nice dose, don't even start about soaking multiple times. On the other hand there are other compounds to put on blotter for personal use, it seems it happens with alprazolam, phenazepam, JWH-018, DOX and NBOMe compounds among others, though it is uncommon...
But please people, distribution of blotters is not desirable: it cannot be controlled if it is going to be passed off as acid beyond some point... besides we do not want to discuss things like distribution here anyway, with blotters it is easy to reach a number of doses considered higher than meant for personal use).
Another thing is that you should not ask for this value if you ever mean to do this yourself, you should test it.
There are different kinds of paper so don't be lazy. You don't even have to ask for a ballpark value if you do it in a certain manner, taring a number of dry blotter (as many as you care to rip a square of for testing purposes), then letting it absorb plain solvent such as ethanol, letting it drip until there is really no drop coming out anymore at all, then weighing again. Start off with the proper mini-plate to contain all of the paper. You will make your scale wet but of course no liquid should come out if you let it drip right. Don't apply pressure when you handle it.
The difference in weight is the exact absorbency value for the paper, use it to calculate other numbers of doses or square sizes.
Yeah using a container to let your blotter sit in when it dries allows for uneven distribution so as is said it will often make uneven doses - don't do that.
If you have calculated the exact value of liquid that your paper can absorb make sure you get a drug solution of exactly that volume, no more and no less. I'd be on the look out for a dish that very tightly lets your paper sit in there - maybe something like certain tupperware is both square and has a size that is only slightly bigger than your paper. But be careful with rounded bottom-edges in the vertical sense.
If you follow all these instructions the paper should soak exactly the liquid that you put in the dish after which you let it dry suspended on something like two wires of viscose stretched in mid-air. Ideally you can tighten the wires like on a violin or guitar to adjust them to be nice and level, as an extra measure for even distribution.
Don't use a micropipette to drop individual hits unless it's for a few occasions only for personal use in which case you normally do not invest in micropipettes. Besides, for personal use you can use other carriers than paper to let your liquid acid dry on. Pop tarts are classic carriers although the most classic one is probably sugar cubes.
I've heard about a sick method for application of LSD to paper that involved misting or creating some sort of vapor (perhaps with ultrasonic waves or something like that?) to get a uniform distribution. I don't know the specifics but in terms of achieving even distribution I can believe that it is cutting edge.
