Rodriguez..
Is there any way you can take a picture of the back for me? It looks like it is done on board (like masonite) vs. a true stretch canvas from what I can tell - which is why I'd have to see the back.
Paintings like this were mass produced beginning in the early 1900's - the "picture" was printed and in some areas, screen painted onto a board (yes it had canvas on it) and then given to artists to complete the "hand painting" portions - complete with brush strokes. They are very hard to tell apart from an all hand painted painting to an untrained eye - and if you dont have a loup and know what pixel and dots you're looking for, you'll never catch it. Same goes for real lithographs vs. fake lithographs - its all in the pixels and dots
Most stretcher canvas arent screened as they couldnt hold up to the process of the machinery without punturing the canvas, which is why board was used - but this is not always the case - it depends on when it was painted.
This looks to me to be around the 1920's-1940's era, give or take. It's very dirty and you can clean it.. if you do it very carefully and as I tell you - EXACTLY - no going off the beaten path here.
First: Is all the paint intact and no flaking anywhere? If so.. you can clean it yourself - if not.. forget it, you'll pull the paint up. Look it over carefully.
Second: Get a potato (not a green one), 2 damp very soft cloths (like a baby diaper, nothing that can "pull") and another dry soft cloth.
Cut the potato in half - begin in one corner and CAREFULLY rub the raw potato over a small area at a time. Let it sit for about 2 minutes, then wipe with the first damp (very damp - not WET) cloth. Wipe with the dry cloth immediately - then repeat with the second clean damp cloth again - then dry again. You want to BLOT dry, not pull across - very important here. Then... proceed to the entire painting.
Once completed - let the thing air dry for a day (it should NOT BE WET AT ALL during this entire process - when I say damp.. I mean very very little water, just enough to get the starch off). Make sure all starch is off or it will change the color of the paint.
You can repeat this process a few times over the course of however long you desire. Be careful though - if you see any paint coming up (not grime..but actual paint colors) stop immediately.
I'd start with the sky area - and go from there. It looks like it has alot of maybe grease or nicotine on it. The potato should pull all of that right out for ya (again, please make sure the paint is not pulled up in any spots).
I just posted on another persons thread on people to contact regarding paintings, prints and lithographs, so if you want to, you can call them as well, but I think since you dont want to get rid of this (and again, I'm pretty sure its 1920-1940 era), you dont need an appraisal or anything.
If you have any other questions - feel free to PM me, I'll help all that I can.
ETA: The signature looks to me like "Rakyin" "Rakyh" "Rakyi" - one of those - its definately RAKY - the question is what is the last 2...
ETA#2:
the C2322 or whatever number you have on the back that you found - my bet is that its the catalog number for the painting, a common practice from back then so that others who saw it, could order it off the back number (again, usually out of a furniture store). However, it could be one other thing as well: have you measured the painting? See if it measures out at 22 inches by 23 inches
You never mentioned what size it was.