I'm putting down a prefinished 3/4" x 3.25" RL hardwood floor (cabin grade red oak, US Floors, lots of 'character'). Got this at a liquidation outlet, because it was cheap and is going into a rental property. I'm stapling it down using a Bostich air stapler with a MIIIFOOT-KIT (supposed to not mar the surface as much plus has wheels on it to speed up install). This is going over plywood subfloor over crawlspace (put down rosin paper, now I'm going to tear out what I've done and start over after reading here about aquabar-b. I've insulated/6mil black poly in the crawlspace but want an extra layer of protection).

Here's the problem I'm having:

After I nail down a board, I look at what I just nailed, or the board behind it, and I'm getting long cracks in the finish/surface of the board. I'll take some pics and post here later, but what could be causing this?

I'm a DIY'er, not a pro, but I have put down hardwood floors in the past and haven't had this problem.

I was whacking the nailer a little harder than needed in spots, just to knock some bowed boards in place, but even when I'd hit just hard enough to fire off a staple, I'll still get a few cracks. I'm not getting the cracks in every board, just some.

I'll admit, I put this stuff in the house this past Tuesday, and probably need to wait a few days more (the house has HVAC and I've left it on 72 for the past 2 months).

Is this a not-long-enough-to-acclimate problem, or does it sound like a defect in the finish?

How many more days should I wait before resuming?

Thanks for any advice.

Air is to high I bet. Plus I hate that foor kit, never has worked for me. I does not allow a perfect hit in the crotch. Least for me anyway.

Thanks - I had the air set to 90 psi, but backed it down to 80. maybe I should go lower? not below 70 or so?

The foot kit helps a little - bigger foot gives it a little more stability, but I'm still prone to operator errors and I've already ripped up about 5 -6 boards because I stapled through the finish...

I'm trying to figure out how to post pics...

You sure those splits weren't there already B4 you put'm down?

Looks to me like it possibly could be how the nailer sets on the wood profile. When your wacking the nailer with the mallet..part of the nailer is striking horizontally on the meat section of the wood profile, above the tongue
I've seen this cause cracks in the middle of a boards. Also seen this caused by whaling on a taping block, at the same profile location.

Thanks for the responses - I've backed my air pressure down to 60 psi, which is just enough to actuate the stapler and set a staple far enough into the tongue. I think some of the boards have a defect in the finish, because I'm looking them over and pulling out about every 5th or 6th board. This is crap wood.

The nailer striking the wood sounds plausible, I need to look at the bottom / foot kit and see if there's some damage to it or something that could be doing this.

Turning the air down seems to have helped a lot, but I still occasionally get cracks in a board I just set, and have to rip it out.

Thats why they call it cabin grade, lots of junk in there.

well the knot holes, burns, wide color variation, worm holes, even the sections where the tongue is broken off - all of that I can live with. when I pull a piece of wood out of the box and it splits down the middle in my hand - no sir. I mean come on, if you're going to sell me crap wood, at least give me something I can work with!!! knot holes can be cut around, 'character' can be spread around, but I can't do anything with split boards or bad finish!!!

I'm in no way a pro, but rather just a DIY'er. That is truly unfortunate !!! I agree with you, that even though it's on special, and not expected to be perfect quality, they should at least sell you something that is usable.
This is why I don't buy from lumber liquidation centers. The old saying you get what you pay for really applies at these places. If you figure the waste, not to mention the headaches, you would have been better off paying double what you paid, and gotten something worth every penny.
As you have found out, (unfortunately the hard way) when it comes to wood, "deals" are sometimes very costly.
Hope you can finish your project without too many more headaches.

hindsight is 20/20. I think this is just a bad batch of wood. maybe I'm wrong, but it's already paid for, so it is what it is. also 'use constitutes acceptance', so what I've already put down can't be returned.

I bought a router bit set for cutting tongue and groove in the wood, so I plan to get as much out of it as I can. also plane/refinish some boards, maybe use those in the closets.

I totally agree, next time I'll pay more for better quality wood, will probably save time/money in the long run. Since I'm way, way, way short on money right now, and have lots and lots and lots of time on my hands, I'll spend it on developing my skills of getting the absolute most out of the crap I've got to deal with.