One of the pitfalls of starting out in electronics (I found) is that you have a lot of hair-brained ideas that you want to try. And sooner or later you out grow the usefulness of the bread board and start making "real" PBCs. By "real" PCBs, I mean good 'ole copper clad boards etched using the toner transfer method. It's a real mess - but I think it's a really valuable skill for a beginner to learn. And, unlike a breadboard, you actually have something to keep and call your own!
Anyways, about 4 years ago, I saw that someone said that you could protect the finished copper clad board with polyurethane once you were done soldering. So , I grabbed a scrap of PCB and scrubbed it up till the copper was shinny. I then sprayed 1/2 the board with polyurethane, and left the other half bare. I put it on a shelf, and it's stayed there ever since. That was four years ago.
I know the test could be more scientific, like measuring the thickness, but I think you can see the results. I'm not sure if the corrosion would create a seal from it further corroding or not . I know some roofs are made out of copper. Maybe 1 ounce copper clad board is too thin to make that happen? Either way, it keeps the board looking presentable and you can still de-solder and re-solder pads if you need be - the polyurethane just melts away under the heat of the iron.
You can see I'm using the "Minwax" brand. I think I paid $3 a can for it at Walmart. I prefer the satin or "semi-gloss" finish. The gloss looks great, but if you get any dust or lint in it while drying it ruins the effect. The satin seems to play the part much better. Drying time is about 30 minuets. Sometimes I speed that up with a heat gun.
Now if I could only find polyurethane in a translucent green color...
Hope this helps someone!