What are some effective ways of sealing an opened tube of caulk so that the contents do not dry out? In the past I've used a large nail and some tape, but that doesn't seem to last for more than a few weeks.
Plastic wrap (Saran wrap) and an elastic band.
I use screw on electric caps. I always seem to have a few around, and you don't need a screwdriver or drill to get it on the tube. It works well, but like most of these solutions it is only a short term solution, once you open a tube of caulk it has a shelf life and if you don't use it you lose it.
The best solution I've found is to fabricate a container out of PVC pipe and two end caps, found at any hardware store. I cut the PVC pipe to about 12", permanently glue one end cap onto the pipe and use the other end cap to seal the pipe without glue. I place a small rubber cap from my junk drawer onto the open/cut tip, spray a small amount of Bloxygen into the PVC pipe, insert the caulk tube and place the second cap onto the pipe. I keep the containers standing upright with the tip facing downward to ensure that the Bloxygen encapsulates the tip instead of any air that might remain inside. This is because Bloxygen is heavier than air. I've also used clear acrylic tubes with caps, which work better because I can see what's inside and they have a flat bottom, which enables them to stand up while stored. It's just hard to buy a small quantity of these since they're sold in bulk. You can find out more about Bloxygen at: http://www.bloxygen.com/ It costs about $11.00 per can plus shipping. Note: I have no connection with, or interest in, Bloxygen other than as an end user of the product.
No, this is not spam. As I mentioned, I am an end user of the product and have no connection whatsoever with Bloxygen. I'm just a guy in the same boat as many in trying to find the best way to save partially used caulk tubes. I came across this product a while ago and have been able to save a lot of expensive paint, adhesives, caulks, etc. I just thought my suggestion might be helpful to someone. If not, just ignore it.
Lee Valley Nozzle Caps or Twist and Seal Stoppers
I've been using Little Red Caps for the past two years; they're little rubber caps that you roll over the end of a caulk tip, and they seem to make a nice tight seal.
I've used them with drywall glue, construction adhesive, and silicone caulks, and all were easy to use and reuse. I've been using one particular tube of silicone caulk for six months, about once a month, and every time I roll the red cap off, the caulk is as fresh as new.
I used to use a drywall screw, but that method only works for smaller tips, and also can rust closed if there is even a slight imperfection in the seal.
I have used the little red condom caps with satisfactory results. But with a construction adhesive or silicone, which tend to solidify despite the red cap, I would use the "blob method" in conjunction with a long (3" or better) coated deck screw (or zinc bolt) plus a washer. The washer helps give you something to grab on to when removing your screw stopper and any dried material that comes with it. The longer and fatter the screw, the better. A longer, fatter, screw will ensure a channel remains for the good caulk/adhesive to flow out of. All else fails, I start cutting away the nozzle.
I use Keokuk Caulk Wax. It seals anything that comes in one of those tubes, adhesive, caulk, silicone, etc., and i've had caulk last for well over a year and a half with out a problem. I have yet to lose an open tube. the other nice thing about it is that you can seal a bunch of tubes all at the same time without having to buy a whole bunch of different caps or plastic plugs. unfortunately you can only get it on line right now, but I think it is around $7 and i have sealed probably 60 open tubes and i still have plenty of wax left in the can.
I tend to use a 3" deck screw. The coating makes it less likely to rust (but I still squeeze out some caulk into the trash until it runs clean). And the 3" is usually long enough to reach the caulk that hasn't dried. The benefit of the screw is that you pull it straight out with a pair of pliers and it will take any dried caulk out with it. If there's too much dried caulk to pull it straight out, I'll often cut the tip larger.
I prefer a hot-dip-galvanized 16d common nail; something in the zinc seems to slow down curing a little. If the caulk still dries in the tube, I curse myself for being so all-fired cheap and go buy another tube - each tube costs less than a pack of cigarettes, a gallon of gasoline, or a cheap meal.
I supposed one could seal it easily with some polycaprolactone. It's a thermoreversible hard plastic which remelts to a clear putty like state when dipped in boiling water for a minute. It can be reused over and over and when cooled back down returns to hard white plastic. it bonds extremely well to other plastics like the plastic used for the nozzle of caulk tube, would definitely seal it off probably as good as a new tube is sealed off. I have some and came across this and just though about it and will try it just thought I'd pass it on. Also if it won't be used for more than a few months consider also sealing the bottom, most caulk rubbers cure by moisture in the air (humidity) finding its way in and doing the irreversible crosslinking. and the bottom plunger does not seal it off perfectly otherwise it wouldn't slide.
I found a pretty good product at Menards called Seal-A-Tube made by Core Gear. It's a plastic cap with a long plastic pin inside of it that goes into the caulk hole that you've cut open. They cost less than $2 each. I tried one out and liked it so much I bought about 5 more. So far, every tube I've taken this cap off of was ready to go again and not dried out.
A wooden golf tee sealed with electrical tape. Have had opened caulk last for multiple years opening multiple times along the way. Use the shorter version or snip off to about 1 inch. Stick the tee in and then 2 pcs of tape pulling down the tee to seal it. Then wrap tape around the tape you just added so that it holds it in place.
Went to Menards and got the plastic tube sealer with the long plastic stick in the middle for $1.99 each.if your caulk is quite old and hard inside the tube I micro-wave the tube for about .25 seconds making sure there is NO metal on or inside the tube and remove any left over caulk in the tip. Works like a charm.