Soldering wire

This topic contains 48 replies, has 14 voices, and was last updated by  NealXu 1 year, 9 months ago.

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    I have been using the double heat shrink method for years now. One way to guaranty a good solder joint.

    Agreed. And I use dual layer heat shrink on more than just soldered connections… I use it on crimped connections as well. Even factory crimped connections, especially where galvanic or electrolytic corrosion is involved near acid batteries. See photos below…

    And for the Bosch Brethren among you, notice the Bosch heat gun in action, standing on it’s back to enable hands free operation, allowing me to work with the cable and heat shrink material to get it into position.

    Large diameter, high shrink ratio (3:1 or my favorite 4:1 from Raychem) is expensive, so I try to cut just enough to engage a good seal all the way around, as well as reinforce the transition points in the connector to cable jacket junction, but not waste heat shrink material by having it run too far up the cabling.

    So the Bosch tripod design enables me to have both hands free to keep the shorter tubes of heat shrink from blowing off target position (dead centered over jacket transition) from the hot air of the heat gun (even when the fan is set on the lowest position, heated air expands, and the expansion of gas creates a wind current of its’ own.

    Notice also the curling tip on the end of the Bosch, that wraps the heat output around the cable, while deflecting it away from my face while working with it.



    I have been using the double heat shrink method for years now. One way to guaranty a good solder joint.

    I just realized that there could be confusion on what I mean by “dual layer” heat shrink tubing, versus how “double heat shrink method” could potentially be interpreted, and wanted to clear that up, because I’ve done both, and they are different.

    I’ve used “double heat shrink” in instances where I needed a wire code number permanently super imposed on the connection, that won’t rub off, and can’t easily be washed off or peel off from heat. An example of this is referenced in one of my photos posted above.

    But even in that example, I also used “dual layer” heat shrink first. And dual layer has an adhesive liner inside that doesn’t just shrink per se, it actually melts… and thus expands, by flowing outward axially as the main shrink tubing constricts around the joint. As the flow of sealant emerges from both ends evenly and circumferentially around the cable and connector, the heat is removed, and the sealant cools like a permanent caulk joint between the cable and the heat shrink tubing. That is what I mean by “dual layer.”

    Now, in cases where I have run out of dual layer heat shrink, I will then double heat shrink the connection using two different concentric diameters of regular heat shrink tubing that often comes included in electrical accessories kits that I never use (preferring dual layer) but won’t throw away (in case I ever run out of dual layer).

    The trick I learned with doubling heat shrink tubing is to NOT do it one at a time. For best results, the doubled heat shrink layers must be shrunk SIMULTANEOUSLY, not sequentially. That is why not only successively declining concentric diameters are needed, but also depreciating lengths. The smallest unshrunk diameter, that is positioned in actual contact with the cable, needs to be the longest. The next heat shrink layer over the top of the first needs to be shorter, so that the shrink status of the original layer can be monitored. If then adding a third layer for cable ID, then that one will have to be larger in diameter and shorter still.

    Double (or even triple) heat shrink layers are still not as effective as “dual layer” adhesive lined heat shrink. Here is a photo of the circumferential “caulk” sealant that oozed out of the inner layer of the lined heat shrink tubing when the joint was completed. Sorry the photo is a little fuzzy.


    edmonton, AB

    Thanks for all the info cb I’ll have to read through a bit closer when I’m done work today



    That dual layer heat shrink tubing is all I try to use, It’s waterproof and great for marine or exterior use. Eliminates the possibility of corrosion


    Fayetteville, NC

    Very nice work on the heat shrinking. Where can you get the double layer stuff?

    Automotive Pro
    Fayetteville, NC


    Etobicoke, ON

    Double (or even triple) heat shrink layers are still not as effective as “dual layer” adhesive lined heat shrink. Here is a photo of the circumferential “caulk” sealant that oozed out of the inner layer of the lined heat shrink tubing when the joint was completed. Sorry the photo is a little fuzzy.

    Photo might be a little fuzzy but your explanation was excellent.
    Yes, I misunderstood your meaning and now know the difference between the two.


    “If you don’t pass on the knowledge you have to others, it Dies with you”
    — Glenn Botting



    Very nice work on the heat shrinking. Where can you get the double layer stuff?

    I mentioned Raychem as being my favorite in one of my earlier posts, but I’ve used a variety of brands of dual layer heat shrink, from a variety of sources, including Harbor Freight. Be careful, and thoroughly read the labels there, as HF sells several different kinds of heat shrink, most of which is not dual layer.

    The quality of Raychem heat shrink is unmatched in my experience. Raychem INVENTED heat shrink tubing, so they seem to have a handle on how to make it right. It was initially invented to serve the military aviation and space industry in the post Sputnik race that begun in the very late 50’s, and continued to the moon in the late 60’s. When I huddled around a black and white TV to witness that giant leap for mankind, I had no idea then that 50 years later I’d be using some of that technology as casually and as commonly as a No. 2 pencil.

    Raychem also invented cross linked polymerization of wire insulation, using radiation chemistry, hence the name Ray Chem (but originally named Ray Therm, because their original inventions revolved around the thermal properties of wire and cable jacketing). Crosslinking the molecular constituents of the jacketing enables the wire insulation to withstand higher temperatures.

    That benefit returns us to the original point of my posts and pics in this thread, which evolved by supporting the earlier recommendation of third hands and alligator clips, and then expanded to recommend also using aluminum heat sink alligator clips to wick away excess heat to the surrounding air, to redirect it from travelling up the wire itself, which otherwise remains a very efficient conductor that acts like a heating element that bakes, burns, brittles, browns, boils, melts or messes with that insulation.

    Getting a ductile, durable, abrasion resistant, non conductive, thermally tolerant wire insulation just right is where Raychem’s seminal chemistry and process application engineering hit the mark. Even with my fancy schmancy Bosch 1943LED heat gun with operator controllable heat level settings, I can still burn through lesser brands of heat shrink if I’m not careful, like the crap Radio Shack foisted on folks in their final declining decade. But I’ve never burned through the real deal Raychem SCT.

    I implied that Radio Shack was going out of business before their doors are fully shut, but even though Raychem was a former Fortune 500 company operating in 60 different countries at it’s peak heyday in the mid 1990’s, with annual sales reaching the billion$, Raychem is no longer in business. But that wasn’t because their products sucked. It was because their products were highly sought after, and Raychem was bought by Tyco International, which itself was eventually split into several independent companies, one of which is called TE Connectivity, which owns and produces the Raychem SCT line of dual layer heat shrink tubing today.

    As an aside, the name of the final Raychem CEO who sold out the company? Dick Kashnow. Can’t make this kind of stuff up.

    I’m going to attempt to attach a specifications sheet from TE Connectivity that covers the open and recovered diameters of the five different sizes available. But if for whatever reason a PDF attachment doesn’t work, you’ll at least have all the keywords from my post to make your own hunt for the product a simple matter of search, where you might find a supplier in your country or locality.

    And not to forget, Raychem isn’t the only brand of dual layer heat shrink out there. They invented the stuff, but 50 years later (Raychem would have been 50 years old this year, in fact) there are dozens of other producers of adhesive lined heat shrink on the market. The things to look for are

    – high recovery ratios ie, 3:1, 4:1, so that the tube will slip over wide terminal collars, and still shrink down to wrap around skinny wires. If the pdf attachment works, you will have to do your own math to determine ratios between the as shipped and as recovered states of the heat shrink, but that is easy enough to figure out once you get the data

    – cross linked jacketing, reduces propensity of heat shrink to open up in the middle after reaching it’s fully recovered (smallest diameter) state. What can cause that is a hot spot on a bare metal conductor or crimp sleeve, that still may have residual heat from the cooling solder, while not enough heat at either end of the heat shrink tube has been applied yet to fully recover it. Another way that heat shrink can burn through in the middle is with open flame (using a bic lighter or butane pencil torch) unevenly applied to the tubing. More of an operator error than a product fault, but some products are more resilient and tolerant than others, and in heat shrink, those tend to be the higher quality and more costly options.

    – and finally, you are looking for the adhesive interior lining that oozes out to complete the water tight seal once the tubing has shrunk to a tight interference fit around the conductor splice or connector attachment.

    Online purchase sources include Grainger, McMaster Carr, Mouser, DelCity, DigiKey, literally dozens of sources too numerous to comprehensively list. And believe it or not, the dual layer “marine grade” heat shrink that is sold at Harbor Freight as a kit in a lidded plastic parts organizing tray is actually pretty decent, especially for the price, if that is a concern. (But NOT the various heat shrink tubing sold in a carded bags… read all the descriptions before selecting.)

    Attached: Publically released Raychem SCT dual layer heat shrink specifications and testing parameter pdf from TE Connectivity.



    My math was wrong in the post above. Raychem would have been 60 years old this year. I can’t edit the post because I already edited it once to correct a spelling error, and if I edit it again within a certain amount of time, the antispam software that BTP uses will make the entire post disappear, which would have been a lot of typing down the drain. (This has happened to me twice beforehand, in my short time here). Just didn’t want you to think that my calculator needs new batteries.



    Hi…as per my knowledge using an acid to clean and I guess etch it makes it go so much easier. The solder will just get sucked in. Also make sure you have a quality iron. I have used some cheapos and they just make it a struggle.

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