Denny Anspach <danspach@...>
Ed Mines writes-
> Does that barge cement make stringers like Walthers Goo?Generally no, and in this regard it seems to be much better than GOO, as explained below .
Virtually all contact cements that I have been acquainted with develop "stringing" whenever the newly-exposed glue is allowed to "wick off" its solvent, either because excessive exposure of an open tube, individual characteristics of volatility, or because of relatively slow user application.
The GOO solvent is relatively very volatile. This is the characteristic that allows it to be in "full contact mode" quite rapidly (two minutes!), but it is also the same characteristic that promotes stringiness when an application may be taking some time (the solvent is rapidly wicking off the second that the cap has been removed). In my experience, because of excessive solvent loss each time the cap is removed, a tube of GOO once opened, also seems to last no more than a year, or less- the stringiness finally becoming impossible to deal with.
The Barge Cement solvent seems to be much, much less volatile, the first clue to which is the 10-15 minute interval required for it to develop "full contact mode" (up to seven times GOO's time). This same characteristic then allows its use at a fairly deliberate pace, and over a longer period of shelf life, without developing strings. It also allows it to be used in VERY tiny amounts, something I have never been successful with GOO.
Barge Cement will age just like GOO, once the cap is off. I minimize it by almost never taking the cap off at all. I drill a hole in the apex of the cap just large enough for a repetitive snug fit for a "T" specimen pin (c. 0.060" , if I recall). I use the pin as a "plug", and I apply the cement only through the hole in the cap. It is amazing how tiny an application I can make (i.e. a tiny speck to secure a retainer valve). Any type of pin or other bent wire can serve the same purpose.
Another method to increase usable shelf life: keep the tube in the freezer. It works.
I have had to discard one Barge tube after about 2 years because the glue did indeed become eventually too stringy .
I install the Plano, Kadee, and other running boards with Barge. I simply place mere droplets of the cement (as squeezed directly through the tiny hole in the cap) rapidly along the center line of running board supports, replace the pin in the cap, and then press the running board in place. The slow set up time allows precise positioning, and also allows fingers of the still fluid (but increasingly viscous) cement time to penetrate the interstices of the boards sufficiently to provide a firm and lasting elastic bond. Within ten-fifteen minutes, the cement is now is full contact mode, and one can now take advantage of this to make certain that all joints are net, and stay so.
Denny S. Anspach, MD