From: "kenneth knaell" <email@example.com>
Subject: Re: Tip tinning
Date: Sat, 8 Jan 2000 17:39:08 -0500
There is probably some sort of oxide on the surface. If you are in a
hurry you may have to file it lightly until you get at least some surface
cleaned up that will tin properly. Also an intermetallic compound ot
tin/copper (speculum metal) forms on copper soldering iron tips after long
period where they are left hot such as at soldering stations although I have
not seen this so much with iron clad tips. This can be forceably removed by
gripping the hot tip with a pair of old long nosed plier and breaking up
this thin layer of speculm metal. The thin layer of speculum metal is very
hard and brittle and will break up easily. Do not file the tip if you think
it may be iron or nickel clad obviously.
The proper procedure is to geat a tinner's block. This is a block of sal
ammoniac which is the common name name for the chemical compound ammonium
chloride. It looks like a salt lick used for farm animals. With the
soldering tip hot and with alot of solder adhearing, the tip is scrubbed on
the tinners block. This works best if there is some area of the tip that
has a semblance of tinned area already available. This tinned area will
then spread out as the scrubbing takes place. It is best to use solder that
has an excess of tin for this purpose like the eutectic (58%tin/42lead or
close?) electronic solder or the (98%tin/2%silver) plumbing solder.
When the scrubbing process is working best a haze of smoke should be comong
off the small area of the tinners block where the solder and tip are heating
it up. This smoke should smell like a ammonia or chlorine or a combination
of the two. This smoke is probably no more dangerous than sniffing a bottle
of washing ammonia or getting a whiff of chlorine at a swimming pool but
prolong try to avoid the fumes obviously. The best way to use a tinners
block is as a routine maintenance treatment of soldering iron tips rather
than let them get completely detinned and have to restore them.
Some small electronic tips cannot carry enough heat to make the tinner's
block work easily but I have never had one that I could not restore. I
think the heat from the tip has to actually decompose the solid ammonium
chloride to make this work well . What usually happens with clad tips is
that the solder bridges over the iron oxide (rust) spots underneath. It
then looks like the tip has been thoroughly tinned but only little areas
have been tinned and these are holding the solder over the corroded (rust)
areas. The solder bridges the rusty areas in this case. Usually the little
tinned area lose their tin coating and the tip then appears suddenly
detinned for some strange reason. This may be what you have observed.
Continued use of the tinner's block usually wins out in this war.
I think it better to keep the tips well tinned even though the abrasion on
the tinners block may cause some wear. I believe rusting of the bare iron
tip causes pits that degrade the tip quicker than the mild abrasion on the
tinner's block does. Eventually the cladding on a clad tip wears through
and the copper underneath begins to dissolve quickly in the solder which is
constantly being washed over it.
The tinner's blocks are *very* cheap at a plumbing supply but you can pay
outrageous prices for an small equivalent at an electronic supply.
More than I started out to say.
Justin Headley wrote in message <38763A5A.873F3E0E@centralva.net>...
>I've been using 30W soldering irons for some time, but i can't seem to
>tin the tip of my 100W soldering gun. I haven't been able to do it for a
>while, but now i need to actually use it, and when i tried to tin it
>again, it didn't work.
>Here's what i did :
>Pull the trigger, wait about 10 seconds, and then dip it into a jar of
>flux. Then i use rosin cored electronic solder, and apply the solder to
>the tip and it looks like it goes on very nicely. But then after about
>30 seconds, the tip goes brown, and if i clean it off with a sponge, it
>turns weird colors, although most of the time the tip is brown. Any
>suggestions on what i should do?