The basement bathroom has no window to the outside, so we framed two openings at the top of the wall to install some of those used glass blocks I bought off Craigslist about three years ago. (I installed glass block sidelites by the front door and learned a few things.) I read in a popular home decor magazine that glass block is no longer trendy, but I don’t care. I love the light effects day and night, inside and out, and the slightly green/turquoise tint.
1. We lined the opening with painted wood. A plastic floor guide was screwed into the bottom of the frame.
2. The blocks have been stored outdoors, so needed scrubbing to clean off the old paint or mortar and leaves, etc.
3. Special glass block mortar mix
4. When mixing this fine, corrosive powder, wear a mask and use gloves. This is the main lesson I learned from last time – don’t use bare fingers, because your hands will suffer all sorts of injury/pain.
5. Add acrylic (Weldbond glue) to the water to increase strength and adhesion.
6. Add liquid to powder (about 1:5). Mix thoroughly.
7. Our mortar mix had absorbed some humidity over time, so the hard lumps had to be removed and discarded.
8. The right consistency is dry-looking, and falls off the trowel in one big lump.
9. Gloves, tools, equipment are cleaned in a bucket. Mortar mix in your sink will harden and plug the drain eventually. Bucket dumped outside when done.
10. Apply the mortar in a generous layer on the bottom and sides of the opening, Then, “butter” the glass block itself before placing it into position.
11. The mortar wants to slide off the block, so I use the trowel and my fingers to push it firmly into the spaces. This is messy work, with lots of mortar falling to the floor and getting on every nearby surface.
12. Once the block and mortar is in place, check level and plumb. Make adjustments where necessary. I used some plastic spacers as “convincers.”
13. I used blue masking tape as an edge guide on the inside. It kept the painted wood clean, too.
14. Brick ties nailed onto sides to strengthen the row.
15. After a couple of hours, clean excess mortar and smooth joints with a well-squeezed mason’s sponge. Rinse sponge often, and buff with a soft dry cloth.
The end result 
(Thanks to Tess for assistance with photos.)
And, an add-on: I have trimmed the openings with wood and paint. It looks much better, don’tcha think?
Outside trim
Wood trim inside
{ 2 comments… read them below or add one }
Good photos Tess. Another piece of the puzzle in place Gail. Light coming the glass blocks, very warm look.
This makes brain surgery look simple.