If you have those old wooden windows, which haven't been painted and refreshed for a loooong time and you don't want to or can't buy new ones (which is a big investment)...maybe it is time to get things into your own hands and get the most you can from the old windows you have.
This instructable is for those that haven't done this ever and are thinking about windows repair inside the house.
Step 1: Prepare for Repair
First, scrub that old paint where it started to fall off. You don't have to scrub all of the paint, leave the old paint if it is firmly attached to the wood. Also remove pieces of wood if it started to chip or if the wood is soft (destroyed by the moist).
On old windows you will probably find that old caulk (window sealant made of clay and linseed oil) somewhere it will have cracks and somewhere it will fall off from the window. Remove the caulk if it started to fall off, but you can keep it even if it has cracks as long as it holds nicely to the wood and the glass.
In the end of this step your windows will look even more ruined than at the beginnig - that's good.
Step 2: Stucco, Sand, Caulk and Tape
In this step you repair the damaged parts by applying stucco with a plastic or metal spatula. Try to make nice surface as you will have less work sanding it later. You can apply stucco also to the cracked caulk that you decided to keep.
The stucco drys about 2-3 hours, except on those places where you applied a lot...I usually let it dry for about 6h. After drying, sand the rough surfaces with fine granulation sandpaper (I used 250 granulation).
Put new caulk where it is missing. I use the same old type of caulk (linseed and clay) but probably there is some new type maybe if you don't want to wait to dry (i think it needs around 10 days to harden and even a month to fully dry...but you can use the windows it doesn't matter if it's not dried). For applying caulk you can use spatula or your fingers (if you are a PRO like me).
Protect the glass before painting with tape and than clean everything. You can use wet cloth to wipe everything nicely especially dust and dirt, everything else will be covered by the paint.
Step 3: Painting
On the end you're ready to paint the windows. I used ordinary oil-based white paint, applied once, then waited 24h and applied one more coating of paint.
You can also paint the outside sill, the oil colors can also be used on metal surfaces.
I also painted the caulk although you shouldn't do that before it dries out, but i didn't want to wait 10days. The problem when painting fresh caulk is that the paint will take a long time to dry and it can sometimes form creases...but I painted it in really thin layer so i didn't had that problem. It doesn't matter if the paint on the caulk is still fresh, you can close the windows and they can get wet (the paint is oil based, also the caulk).
After all, if doesn't turn nice and you don't like it, repaint the caulk when it dries.
The end result is really impressing if you consider how the windows looked.