adhesive for Teflon/PTFE

[michael howarth 1Participant @michaelhowarth1]

I would like to secure a 4 or 6BA stud into a piece of PTFE rod……which adhesive can I use? Or am I on to a total loser on this one?

Mick

[michael howarth 1Participant @michaelhowarth1]

[Boiler BriParticipant @boilerbri]

If you undercut the hole you have to put it in then fill it with epoxi resin, set your thread or bolt head into the resin. Should hold up. Araldite is what we use.

Brian

[Bob Brown 1Participant @bobbrown1]

To quote "Permabond also offers TA4610 (and a range of similar products with varying cure speeds). This is a two-component 1:1 mix ratio structural acrylic which can be applied, without primer, to untreated PTFE surfaces and achieve a reasonable bond strength on this non-stick nasty!"

[Roy MParticipant @roym]

Depending upon your application, you can secure screws by drilling a hole about the same size as the core dia of the thread, start thread with a tap for one or two turns.Then "self tap" the screw to depth. This grips very tight. You may get improved results by a few trials. Roy M.

[Roderick JenkinsParticipant @roderickjenkins93242]

I was under the impression that you can't glue PTFE but one of our adhesive specialists told me that it was easy – epoxy resin will do it, all you have to do is etch the surface with Hydrofluoric Acid

So, sorry Mick, I think you are on to a loser

Rod

Edit – others' experience suggests there is chance so good luck!

Edited By Roderick Jenkins on 28/10/2016 19:11:34

[V8EngParticipant @v8eng]

I remember that Loctite make a two part product for bonding plastic products, PTFE is listed amongst the things it can bond.

I think the info is probably on the Henkel site.

[mark smith 20Participant @marksmith20]

Why not this?

**LINK**

[Jeff DaymanParticipant @jeffdayman43397]

In my experience I have seen exactly one instance where glue can be made to bond at all with PTFE. It was a special treatment with HF acid mixed somehow with hydrogen peroxide and then swabbed onto PTFE film about .008" thick. Operator doing the treatment had to wear full rubber outfit, scuba type breathing gear, and work behind a blast proof shield. Apparently after the hydrogen peroxide was added the mixture became unstable and explosions did happen from time to time. Anyway all this effort resulted in PTFE film that was the usual milky white slippery surface on one side and a filthy looking HP sauce-like brown smeared mess on the other. Regular adhesives would stick well to the brown side. The material was billed to the firm for $1200 per square foot. It was used in photocopier machines, sparingly.

I still have about $6400 worth that was thrown out when a lab closed.

Apart from that, glues do not stick well to PTFE. The surface energy is just too low. I have noticed people selling glue and special surface modification machines and methods ( corona discharge machines, lasers, etc) do claim their glues will stick to PTFE/ treatments will help glue stick to it. What they do not say is they will just barely stick to it, not a usable strong bond you would expect from say CA or epoxy glues, and if there is any flexing of the assembly the bond will break.

If you want to bond a PTFE rod to a threaded item, you might try using a hex headed threaded item , drop it in a close fitting hole in the PTFE, and use a heat gun to soften the PTFE, then compress it around the hex head of the threaded item to mechanically couple them.

Word of caution – do not use a flame or let the PTFE burn – it can give off some nasty chemicals when burnt.

Even heating it to soften it should be done upwind outdoors for safety.

Good luck, JD

[michael howarth 1Participant @michaelhowarth1]

Thank you for all the ideas gents. I will have a go at some of them this morning….but I think that I will leave out the HF suggestion! My fall back position, although not ideal was to cross drill and pin but if I can get it to "stick" by other means then so much the better.

Mick

[Raymond AndersonParticipant @raymondanderson34407]

I have used Hydrofluoric acid quite a lot over the years for cleaning old Lime from reclaimed granite. I still have a few litres left at 60% There are safer alternatives available, but are not nearly as good [ need a whole lot of wirebrushing ] with the HF it was simply a case of put it on, and 5mins later the granite was like it was just quarried. It does however have a "dodgy " side .

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Raymond Anderson on 29/10/2016 07:56:42:

I have used Hydrofluoric acid quite a lot over the years for cleaning old Lime from reclaimed granite.

Sure you don't mean Hydrochloric acid Raymond?

Russell.

[Raymond AndersonParticipant @raymondanderson34407]

No Russell I do mean HF not HCL I think the stuff now is based on HCL but is nowhere near as good or quick as the HF. even the Neolith that you get now is far weaker than it used to be.

The HF even fumes when you open the plastic container. but there is nothing better than it for cleaning the Granite. even thick lime is no problem for it. great stuff, but just not very "benign "

[Gordon WParticipant @gordonw]

I've done same as Boiler Bri – Trying to fix a stud into PTFE piston, drill hole a bit tight, open up the bottom of the hole by hand. I don't think it actually glues, just that it won't pull out easily. This was for a little hot air engine so no great load.

[mark smith 20Participant @marksmith20]

Forget about fiddling about with HF ,ridiculous suggestion in regards to safety.

If you were splashing HF all over granite and you were in the vicinity you would almost certainly not be around any longer.

HCL(aq) also fumes when you remove the top from a bottle and flash rusts everything in sight.

[Raymond AndersonParticipant @raymondanderson34407]

No Mark, it is HF and you dont “splash it around” It gets brushed on although the brushes never laated any length of time. Lost count of how many times ive used it although non recently. Common sense and care im still here. I dont advocate anyone using it especially if they are not aware of its lets say ” dodgy ” side.
I dont think members of the public can get it now. I certainly cant anymore. Only that Neolith crap.

[mark smith 20Participant @marksmith20]

And what safety gear were you wearing??

I used this stuff for a number of years analysing radioactive actinides like plutonium, polonium ,caesium ,uranium etc.. at the Sellafield nuclear plant and most people i worked with were more scared of this stuff than the radioactive cocktails we worked with.

I think it was 60-70% we used but even concentrations as low as 2.5% can be lethal and you often dont get any symptoms for several hours or days.

**LINK**

[Anonymous]

Mark: That was an interesting link, thanks. I note that it says HF reacts with silica to produce toxic silicon tetraflouride. Granite is largely silica……………

Andrew

[the artfull-codgerParticipant @theartfull-codger]

I worked in the glass trade for a large proportion of my working life, & hydrofluoric acid was used as a decorative treatment on glass,[it eats glass away] on a lot of your old pub windows/ traditional public buildings etc, our embossers used a combination of hf acid, often mixed with other acids, mica, sand blasting,brilliant cutting & coloured silvering etc & produced some of the most beautifull designs on glass, alas the company we worked for closed us down, & a number of skills were lost allthough some started on their own.

[Swarf, Mostly!Participant @swarfmostly]

Hi there, all,

I hope you will forgive me for an off-topic observation (i.e. nothing to do with either PTFE or HF except that it does concern adhesives and difficult plastics).

I received a couple of items in the Post this morning (they happened to be from Arceurotrade) and I was very impressed by the bond between the flap and body of the mailing envelopes. I had to cut the flap with a knife to get access to the contents. I assume that the packer removes a barrier strip from the adhesive strip and then closes the envelope. That adhesive joint is really, really strong.

It's a shame you can't get that stuff in a tube/bottle!!!

Best regards,

Swarf, Mostly!

[Raymond AndersonParticipant @raymondanderson34407]

Mark, I think the gloves used were by trellchem [ or such like ] made from Neoprene / butyl rubber. and just a plain face shield. nothing more. Would pour some into a plastic pail, Just took a deep breath before decanting it so as not to breathe in , then brush it on leave for about 5 mins [depends on the lime thickness ] and give the stones a good rinse off. leave to dry and presto, Granite like new.. Never any need for wire brushing like the Neolith now.

Andrew, Silicon tetraflouride or no, im still alive and kicking.. I do remember once many moons ago, there were contractors in cleaning the building I was working on. I was rebuilding a new Granite gable and it was a fine summer day so only had a t shirt on. I was always itching on me arms and back, I just thought it was prikly heat or something like that. only when I got changed at night I noticed me t shirt was like a string vest, holes everywhere. It was the "mist "from the lads cleaning the Granite round the corner from me !!

I must have still been an apprentice the first time I used it , although we were made fully aware of its powers. to reshape the human body, and other equally unpleasant outcomes. .Certainly would not get away with that now. HSE has put the mockers on it This new safer stuff needs a lot of wirebrushing and even chipping with a punchin to get most of the old lime off. before applying the Neolith.

Have not used the HF for ages, would'nt get on the site with it now. thats why I still have a few litres left.

I certainly would not recommend anyone to use HF for any purpose.

[Martin WhittleParticipant @martinwhittle67411]

In another life, I have used 'Tetra Etch' for etching the surface of PTFE and FEP wire insulation prior to potting electrical connectors. It was then made by WL Gore, but I cannot find now it on their website. On an internet search I have found a source of it on one website for about £200 + VAT for 500ml (!), and polytetra.de also list it The bottle size I used to use was much smaller (50 or 100ml), and you will find many more web links for MSDS (safety) sheets than you will find any supplier information. I believe it is made by reacting metallic sodium with an organic compound; this then gives a highly reactive compound, quote: "A sodium compound in the solution reacts with highly fluorinated polymers to form a reactive film on the polymer surface. Nearly any adhesive can be used on this treated surface. The active sodium in TETRA-ETCH® etchant reacts with the surface molecules of a halogenated polymer to form a carbonaceous film of free radicals".

Tetra Etch was a remarkably evil-looking black liquid having the appearance of a crusty lava-like skin. I recall I used isopropanol to wash it off after giving a bent-back end of a cable a 30 second dunk in the compound (insulation only, not exposing any electrical conductors). It left the insulation with only a slightest surface milkiness on coloured insulation, invisible on white. I believe the useful shelf life of a treated surface may be about 7 days.

On a tear test, pulling a cable out of a thin surface layer of potting compound, it did clearly gave significantly better adhesion than a similar test on an unprepared wire, but I would say it was still not a mechanically strong joint. Surely not helped by the inherent flexibility of PTFE

I suspect that PFTE can therefore be bonded to the degree that a sealed union may be made, but perhaps not a joint that required to suffer significant mechanical strain.

Martin

[mark smith 20Participant @marksmith20]

Raymond , all i can say is you must be very lucky. HSE didnt seem to exist years ago.

I remember playing with mercury like it was play dough or something. My father in law said when he was studying chemistry they used to suck up sodium cyanide in a glass burette by mouth!

[Raymond AndersonParticipant @raymondanderson34407]

Hi Mark, I think I would most certainly back away from sucking up Cyanide using a burette. Used HF lots of times but never in large amounts. I wish we were still allowed to use it cos it does save a lot of work and time. It is just another in a long list of materials that are banned/ regulated.
I think that up until maybe late seventies / early eighties you could purchase almost any chemical Changed days indeed.

[Raymond AndersonParticipant @raymondanderson34407]

Just a thought, If someone said to me, Raymond go clean that stone with 60% HF or suck up some Cyanide with a burette I think I would take me chances with the HF. lol

[Author]

Posts