Darkroom sink paint - marine topside paint

[bob carnie]

I have used West Systems for all my sinks, every three years I re sand caulk where needed and repaint.

[Serge S]

Hi Drew,

Thanks for the caulking recommendations.
Good to know I need to wait about a week before paint.
Prime also after sealant right?

I found the Sikaflex at Lowes.
Sika White Fast Setting Polyurethane $9.18 (10 ounce)
They also sell the 3M Marine sealant $26 (10 ounce)

[Drew Wiley]

Polyurethane caulks like Sika have a limited shelf life, so slightly squeeze the sides of any tube before purchasing, to see if there is still a reasonably amount of liquid "give" in there. Good idea with any caulk, really. Either style, regular or marine, should work well ln a sink. If you can afford the marine, go that way. Sika is sticky and a bit tricky to smooth, so wear a nitrile glove when doing that. I have no idea what kind of primers Lowe's sells; probably not the best. But it should be a multi-surface variety.

Curing time depends on the weather and humidity. Cold weather takes longer. In hot dry weather it's about a 3-day wait before you prime it. Err on the conservative side, and always wait a little longer.

[Roger Thoms]

Just bought a tube of Sikaflex 1A and it has a expiration date on the inside bottom of the tube. So in addition to squeezing the tube check the expiration date.

Roger

[Drew Wiley]

Yep. But once you start squeezing the caulk gun, you'll know for sure! It will either come out, or it won't. However, it's odd that a Home Center like Lowes would stock Sikaflex. Perhaps that's due to a lot of lakes and boats in Vermont,
as well as the punishment of harsh winter weather to homes. It's a good product line, including 1A, and was popular with the marina and yacht crowd here.

[Tracy Storer]

I used Marine epoxy and fiberglass cloth, think "inside out boat". Sink interior is 30" x 12'.

[Serge S]

Thanks Drew.

You are probably right, as we are on Lake Champlain - one of the largest fresh water lakes in the United States

Yep. But once you start squeezing the caulk gun, you'll know for sure! It will either come out, or it won't. However, it's odd that a Home Center like Lowes would stock Sikaflex. Perhaps that's due to a lot of lakes and boats in Vermont,
as well as the punishment of harsh winter weather to homes. It's a good product line, including 1A, and was popular with the marina and yacht crowd here.

[jp]

If you need a good 3m caulking, there are two choices. 5200 is permanent under all conditions. 4200 is similar but can be softened/removed with nasty chemicals. 5200 is widely used to seal the interface between many types of material found on boats. 4200 is recommended for transducers; binding plastic, bronze, stainless, wood, and fiberglass together below the waterline where failure could mean a sunk boat and/or ruined hull core.

Even though fiberglass epoxy options are smelly, if there is a way to do it outdoors or have someone else do the work, or leave the darkroom fan on for a few days, the results will potentially be very nice. If you are not in an area with marine work, perhaps an autobody worker could help.

[Drew Wiley]

I sold lots of expensive Fein "Supercut" machines which used special cutters of various styles and hook widths to just zipper out marine caulks between the planks. Our window warranty & repair dept - the largest west of the Mississippi - had five of them on every truck. Nobody used nasty caulk softeners on boats or windows or doors, though we offered those kinds of chemical aids to bathroom renovators.

[Dan Dozer]

I used "Flex Seal" for my darkroom sink. You know, the kind on the infomercial on TV. It has worked very well but it is not easy to apply. The product is much thicker than paint and for my 8' long sink, I ended up putting on 3 coats. One quart size cans covered one coat so it ended up costing me more money than I thought. Because it is as thick as it is, it also doesn't go on very smooth and you do get ridges and valleys. One thing it did provide was it was easy to build up the thickness at the drain end so water doesn't pond up at that end of the sink.