aemeijers wrote:
desgnr wrote:
An aluminum double window is hard to open.
What can i use to make it move easy ?

Nobody else said it, so I will- step one is to field-strip and clean
out all the gunk and debris in the tracks, rollers,glide blocks, or
whatever. Is this up-and-down sashes (uncommon in aluminum around
here), or horizontal sliding? Also use Mk I eyeball and a
straightedge to make sure nothing is bent. Post a photo someplace,
and we can probably give better advice.

Amen! Aluminum corrodes (slightly) over time and the corrosion results in
"bumps" in the tracks. After cleaning, go over everything with steel wool
'til it's shiny!

Then lubricate.