Originally Posted by barnakiel
5200 sticks very well to dacron, also wet. Sure thing, you do not want the sail to be oily or anything. It is not very common to have contaminants on a sail though. I wipe with acetone, anyways (this drives some of the moisture out too).
Make some test with old sails next time you have some 5200FC left over. You will get a shocker.
5200 does not stick too well to mylar though. Glue to the taffeta side instead (assuming this is not a mylar/mylar sail).
The mylar one can be fixed with insignia. In a load area I would use stickyback kevlar though.
I always try & get a clean, dry surface to stick things to. Though when at sea this is sometimes tough to do. But one get's creative at times, needs be. Assuming that the Mrs. is willing to offer up her hair dryer
And yes, I'll try out some 5200 on some fabrics which are both wet & dry. Though load testing them will be "fun": In terms of replicating the loads applied both by winches, & those of periods of flogging, soaking, & other destructive stresses that sails see. Thoughts on this?
In the linked thread Mending Sails With Adhesives ?
I mention cautions & problems in bonding to Mylar, Taffetas, & some other films & materials, for several critical reasons:
One being that many of these films have only a fraction of the tensile strength of the sail's actual load carrying cloths & fibers. Let alone actually being able to replicate the original strength of the sails themselves via this method. As in some laminated sails, the load carrying fibers are rediculously strong. Like say, Carbon, Kevlar, or Vectran.
Though at the same time, some of these sails are incredibly fragile. Both the load bearing fibers, & the films they're glued to
And also, some such sails can be too slippery to glue to. Such as in Spectra's case. At least without more specialized adhesives for the most part. And lots of prep steps. With some sail gluing even needing "post-curing" techniques too.
Another issue is that many sails are load path designed. Both string sails, & even within the weave of standard sail cloths. So that it's tough to patch them without creating hard spots or weak spots. Which is true in some Dacron sails, even non-laminated ones. And you can run into issues of bond strengths vs. fabric/yarn tensile strengths again.
For example, look at how radial clew patches & their webbing reinforcements are applied. So that there's a spreading out of the loads in a non-concentrated fashion where each layer of reinforcing fabric
or webbing, is added & teminates. It's a patten with alternating lengths & depths of these materials being added. Kind of in a star or radial, zig-zag layout.
Plus, some of the films in laminated sails can be too slippery to bond to/bond to with proper strength. That, or the films or fabrics may be weakened by some solvents in the adhesive itself, & in some of the prep solvents for the adhesives. The chemistry of much of this being beyond my education at present.
Also, there are a few other issues on top of these
Thanks to the myriad of fabrics out there. With some materials, & sail construction types rendering many high priced sails disposable once damaged
Which is where having overbuilt laminated sails helps, as does an experienced sailmaker
. Hopefully one backed up by a large volume of constructional data.
But most of the above is laminated sail specific. Hence the suggestion to the OP to do some searching for & reading of sail repair threads. And to focus on some of the basics of sewing & hand work, oriented more towards standard types of crusing sails.
That said, for more information on sail design, & construction. Including some info on higher-tech sails, plus other nautical sewing projects, there's Dan Neri's book The Complete Guide to Sail Care & Repair
Along with quite a few others. Including Brian Hancock's Maximum Sail Power: The Complete Guide to Sails, Sail Technology and Performance
Which can be downloaded free as a PDF, in addition to the standard format.