***Dry citric acid concentrations:
Trial and Error, I usually go "too strong ~20%" as I often use it almost
as a wipe on/off cleaner.
Too high will break down wood
Too low won't bleach adequately

***Would applying citric acid mitigate later contamination?
Don't know. Possibly if it kills fungi, appears to stop spalted pieces
from going to rot. Although I haven't done specific testing to determine
this. If I have boards bandsawed from a spalted piece, clean and start
working on a piece then leave it for a while. I've had the worked board
ok and the remainder seem to continue to rot. This could just be an issue
of concentration of fungi and original location of board within the tree/
log, i.e. the source direction of the fungal infection.
The way I use it, it doesn't leave a film or seal to prevent further
contamination. If I leave a tool on the board after treated it will
stain, but the stain can be removed with a further treatment. For
instance, if I get sloppy and get Paduak sawdust on a light board, say
Aspen, I must quickly spray off as much as possible with an oil-less air
compressor (airbrush compressor), then quickly wipe remaining off with a
citric solution or it will stain permanently. I highly recommend two air
compressors for a shop. Oil compressor for air tools and oil-less for
cleaning, blowing the sawdust off yourself, cleaning dust masks,
painting, sealing and any other liquid applications.

***Seal blanks?
I only seal logs, never blanks. Although I do occasionally seal the ends
of large cuts (2x8,4x4, etc.), but I do that to slow drying and prevent
splitting not to mitigate discoloration. I use paraffin wax.

***Bark on?
Don't know. May increase fungal activity. Not enough experience. I
usually cut into as large as manageable pieces from tree, seal both ends
and stack at least 1ft above ground for 1 season, 6-12 months, then cut
to blanks at end of summer and move indoors for another 6-12 months or
until dry.

***Contamination from blade?
Quick wipe to clean board after cutting if needed, usually I wait and
clean after final cut. I use Forest blades with dampeners and don't need
to sand or scrape after cutting for flat cuts. My bandsaw (not mine, but
same one)
http://www.woodcentral.com/shots/images/253inca.jpg
and lathe tooling don't stain. Hand transfer and leaving tools on top of
boards is the main issue for me. I always oil all my blades anyway. But
be careful with bandsaws, your drive wheel may have a rubber tire than
won't like the oil, most are neoprene so they should take it. Make your
own decision on this. Check with a lumber mill or other large bandsaw
user, you'll find almost all oil the blades, but this does not always
mean you should do the same thing on home/hobby equipment. I live near
the coast, fog/rain, so inland operations may differ. The oil is to
prevent rust not to mitigate staining. It is applied after cleaning the
blades/tools with mineral spirits at the end of each days use. Again, do
this on your own decision, some plastics and rubber don't like solvents.
The wipe down at the end of the day keeps the shop clean and ready for
precision work. I definitely will get staining between woods on the
bandsaw if I don't clean the blade. Usually only on the first piece of
light wood after an oily or dark wood. I often cut 1/8" thick for
marquetry, so the sap/oil is a bigger issue and the reason for cleaning.
Again, the oil is used for rust prevention. After a heavy session of
bandsaw prepping, I can go for months without using the saw again, so I
need the protection from humidity changes.

***Wood species to keep apart?
Dark softwoods, oily woods, reds, oranges, and some dark hardwoods.
ex. Bloodwood, Padauk, Purpleheart, Birdseye Redwood, etc.
I always stored my woods separate for easy identification after cutting.
I have too many varieties to tell apart after they're in blocks.
Bloodwood and Padauk, among others, are used to make dyes. The sawdust
colors will amaze you if you haven't worked with them yet. They are so
saturated, you'd swear somebody sold you a board soaked in dye.

***Plastic racking for drying?
I use open plastic stackable racking. Each box/stack can be carried into
shop for matching grain, figure pattern, etc. selection as there is no
light in storage area to prevent UV discoloration.