How do you even start cleaning a five gallon paint spill on stairs?

Stop trying to wipe it with rags; that's just pushing the pigment deeper into the wood fibers. You need to get a **flat-edged dustpan** or a wide drywall taping knife and start scooping the bulk into a fresh bucket. Be careful not to gouge the wood finish, but focus on getting the heavy puddle off the surface before it starts to skin over. Once you've got the thick stuff up, grab a Shop-Vac that can handle liquids. Sucking it up is ten times more effective than wiping at this stage. If you have a helper, have them follow you with a spray bottle of warm water. Mist the area slightly to keep the paint from drying and then vacuum it immediatly. For the baseboards and walls, work from the top down so you aren't fighting gravity twice.

Concerning the stringers and gaps, you're going to have to flush them out. If the paint is still wet, use a spray bottle with a mix of water and a tiny bit of dish soap. Spray it into the cracks to dilute the latex and then use the vacuum crevice tool to pull it back out. If it sits in there and dries, it’s going to act like glue and eventually crack or peel, looking like white chalk in the seams forever.

If the stairs are finished with polyurethane, you have a fighting chance. Keep the surface damp while you work. Once the bulk is gone, use a **microfiber cloth**—not a regular cotton rag—and keep switching to clean sections of the cloth. If you see a white haze left behind once it's dry, a little bit of Krud Kutter or a dedicated latex remover will ussually take care of the residue without eating the floor finish, provided you don't let it soak for too long.

Man, I am so sorry. I’m just starting to do some DIY painting and this is my absolute nightmare. I read somewhere that you can use kitty litter or that absorbent floor powder for spills, but woud that acutally work on wooden stairs? I'd be scared it would just turn into a gritty paste that gets stuck in the wood grain forever. Also, if you use the shop vac, do you need a specific filter for wet stuff? I’m always worried about the paint drying inside the hose and ruining the vacuum. Hope you managed to get it all up before it set!

definatly skip the kitty litter—on wood, it’s basically sandpaper and will ruin your finish. To answer the vac question: pull that paper filter out immediatly. You need to run it with either a foam sleeve or no filter at all, otherwise, the wet paint will clog the pleats and burn out your motor. If you hit spots that are already starting to set, stop scrubbing. Use a plastic putty knife to gently peel the film up. If you force it with a rag now, you're just grinding white pigment into the wood pores. Keep everthing wet until it's in the vacuum.

If you find it's stuck in the wood grain even after the bulk is gone, grab a soft-bristle nylon brush. Rags just push the pigment deeper, but a gentle scrub with the brush and some warm water can lift it out of the texture of the wood. Just keep a bucket of clean water handy to rinse the brush constantly. Also, once you’re done with the vac, clean that thing out immediatly. If latex dries inside the hose or tank, it’s basially garbage. I learned that the hard way after a smaller spill in a basement. It turns into a rubbery mess that's impossible to scrape out later.