mer1122
I've used Tenax and Testors liquid cements. Tenax proved to be too unreliable, so I wouldn't recommend it. Testors, on the other hand, has never let me down.
The benefits have to do with the fact that the tube glue, if I'm not mistaken, is essentially the liquid cement mixed with clear styrene or something similar. This dilutes the solvent and adds a lot of extra material that comes out of the seams that you have to remove later. In my experience, it also means there's more plastic for the solvent to get out of to evaporate, slowing down drying time, hence the 24-hour minimum drying time before removing whatever restraints you use to hold the parts together.
Liquid cement is more potent and leaves almost no residue. The only "glue seams" that will develop are from melted plastic from the parts beng pressed out ( and you have to use waaay too much to get the same kind of seams that are typical with gel cement ). The setting time is a lot less than with the gels, usually 5-15 minutes, but larger joints may take an afternoon. Also, gaps in a seam can be corrected more easily and with less mess than with the gel. Say the middle of a wing's leading edge didn't bond and you have a small opening. Even if you can get the gel in the gap from the outside ( from the inside is almost impossible in such a small area ), it will not be as strong a bond as you'd likely want and easily make a mess. The liquid cement could be used in the same situation, deliver a full bond with little if any mess: just run it from the inside or carefully dab on the outside and let capillary action do the rest.
As always, there are catches. First off, the liquid cement dries really fast and a single application before assembly of larger parts may not be enough. You brush it on the first part, put that down and brush it on the second, try to put them together and there's a less-than-secure bond. My cure for this is multuple coats of cement, alternating between the 2 pieces, until enough cement has soaked into the plastic to allow a bond to form. This usually takes 3 coats, but I've had to occasionally double that.
Secondly, the stuff leaves no room for error. Once 2 pieces are assembled, there's no separating them. Gel cement doesn't form as secure a bond, so parts can often be pried apart if you made a mistake. You don't have this luxury if the liquid cement is properly applied ( the directions aren't quite as "optional" as some of us guys are used to
![Tongue [:P]](/FSM/CS/emoticons/icon_smile_tongue.gif)
) .
Finally, there's the control issue. Switching from an easily-controlled gel to something with the consistency of water takes some getting used to. just make sure you get the excess off every time you dip the brush and it should be fine. Also, just remember that even when using the gel cement it's a lot easier to add a little more than it is to clean excess from the part. The same goes for liquid cements.
As with anything else in this hobby, it's a matter of experimentation and determining your preferences.
I couldn't even find my way back to "normal" with the Hubble!