Wow, you guys are really on the ball and I SO appreciate your help!! The cold dark place makes a LOT of sense in the proliferation of mold....and you're RIGHT in assuming we don't have the lights on all night. The wood we're using is quite varied. When we first started this a 6 weeks ago, we traded filet'd walleye for two tree's that someone had for firewood use and we figured it was sitting there for about maybe 8mo or so...had NO clue when it was cut down. The first 'plaques we did turned out really well, just beautiful in fact with no mold. However, once chainsaw-cut on the angle, sanded twice, then sealed twice on both sides with polyurethane and then stenciled the names on...we let them dry in our "mud room" on shelves. A few of them had little bugs still INSIDE the wood and we'd see teeny tiny little bore holes where the bug had literally 'bugged out"...but no mold...yet.
Around here they do a LOT of logging and we tried to get things as cheap as possible. We finally went to a few places where we could get our wood DIRECT from the loggers. Not knowing much about what ewe were doing...we picked up some maple because it had some really nice bark. Nice bark is really the 'star' of the show as it makes the natural frame just gorgeous. Well maple was extremely difficult to work with as it's SO hard and even when we tried staining it...it sorely lacked the beautifully natural grain that the red oak does. Couldn't really use it tho no mold has appeared on those smaller pieces. Also, with the maple...we used at least a new sandpaper for EACH piece vs. one piece of paper for 5 pieces of oak....so we drop't that maple off to the fella that uses firewood for heat where we first bartered for our oak.
Anyways..we've made about 25 and given them away to relatives 'n friends and even sold a few online to friends on Facebook. Our first sale was to a buddy in the UK which we have not sent his out yet due to this problem. (he has his own lake and wanted a plaque for it) Most of these WILL be put up outdoors...as we have moved into putting photographs (provided) on the finished plaques. This is where we have begun to see the mold...on the ones that are kept inside and with the newly cut tree's. No one that has received a plaque has mentioned ANYTHING about the ones they keep outside having mold...YAY!!
As far as the bleach solution we're using, two parts water one part bleach and it's Clorox. He's also being cheap about it and using the same solution for piece after piece after piece. I TOLD him he's got to change that solution...was I right about that? The bug's...the bugs came out w/o ANY solution..and this was before we discovered any mold..we have not had that problem since but I think it was just that older wood that had been sitting there. We have had vacant spots in the wood meaning complete holes in the slices yet some of the holes in the pieces make it look really good. In fact we use them and some people have requested that they have the thru-and thru- holes in thier plaques...as it makes them much more rustic looking and that's what people up here are all about...rustic.
We'll be going to craft shows and flea markets this coming summer, hoping that this turns into a nice little business for a cupple of retiree's doing custom plaques but if we can't get the mold under control we'll hafta scrap it and only do the 'outdoor' signs/plaques. I'll TRY and post a few pictures of what we're doing if I can figure that out :)
A few minutes ago he called around to a few mills in the area about kiln drying the slices/slabs but that will probably non-cost effective...waiting on calls back and will let you know. I'm thinking we need more of of half and half solution and changing it out OFTEN. We have even used the bleach AFTER it's sealed and before it's sealed...it doesn't seem to affect the poly at all. We have our 1st craft show this wkd, probably a little too soon but we are looking to re-coop some of the money we've already put into this 'project' so we shall see what kind of orders we come up with and not 'push' the picture plaques vs. the outdoor ones....just to be on the safe side.
I REALLY appreciate ya'lls input and thoughts on this, ya know..googling this question came up with TONS of other things and you know how THAT goes pretty soon you're off into something totally different that you waste all your time on looking into and it doesn't answer your original question..haha. I thank you dear moderator for your links as well, it's ALL helpful to some degree
P.S. These are some examples of what we're doing in various stages of completion and YES the plaques are temporarily mounted on a rough cut privacy fence that WE made last summer. We're not new to working with wood exactly...but new to this type of genre.