The stain is inside the wood and can not be removed. However you can lighten up the pews to some degree depending on how much material you remove by sanding the down a bit. Once you get the color you are looking for you should not add any stain otherwise they will just darken up again. If they are typical pews they are probably oak or some other type of similar hard wood and the stain is not very deep. Yes it will take a good bit of elbow grease but if you want to lighten them that is all you can do. I would use a dual action palm sander to get them down quickly with out nearly as much pain as doing them by hand. Good luck. Post a picture when you are done.
There are bleach solutions that will lighten up the stain effects. Any good paint supply provider will be able to provide the chemicals needed. This is done all the time.
I have used a sander and it does take the stain off. I believe these pews wer made of Poplar and the stain is Cherry .I just tried using a bleach and it lightened it up a bit. I guess sanding is the only way to go. I'll post pictures soon. I cut the pews in half to make 2 smaller 4 foot sections and made new ends for one of them.Thanks for replies.
Thanks for the answers, but I'm still hoping for more ideas.
It is very difficult and quite a huge time sink to get rid of all the stain. By the time you sand it down enough, there may not be much wood left. I always advise either staining it the same or a darker color if that is a possible option.
You are not supposed to use house bleach if that is what you did. There are special chemicals just for doing that type of job. Check it out it might help you out and save you some time.
Daniel, I have had good success removing stain by using the strongest paste strippers.
Brush it on heavy with very little back brushing. the gas trapped in the bubbles is how it works. Scrape it off with a flexible metal scraper.
Wash it down liberally with lacquer thinner or MEK.
Then you are ready for a final sand.
It's toxic, messy business and you need a respirator, but it works.
The beauty of the old wood is the old tones. Why are you trying to brin them back to their original wood? How about just finding a stain that will balance the original and then tung oil or Couture Wax (for painted surfaces only) to seal your benches. The luster will bring out the original beauty.