Fender Stage 112 repair - how to tackle burnt PCB

[g1]

What does the identification of hazardous items listed in the MSDS have to do with a products formulation?
It tells you 2 products contain some of the same items (the hazardous ones) but that is all.

[bob p]

What does the MSDS have to do with formulation? A lot more than you think. I can see where someone who isn't a chemist by training may believe that there's some magic hidden ingredient that renders brand formulations different, but there isn't.

Ethyl cyanoacrylate preparations are monomers that react with water. They have to be stored under anhydrous conditions to prevent premature polymerization. These products are activated by exposure to ambient atmospheric humidity, which explains why they have a short shelf-life after opening them. Their susceptibility to exposure to water rules out water as being used as a solvent. That's significant because water is the only solvent that can evade being listed on an MSDS. ECA glue formulations are typically presented as pure cyanoacrylate (Krazy Glue), or gelled cyanoacrylate (Krazy Glue Gel) which is manufactured as a colloidal suspension of ECA with pyrogenic silica.

If some other formulation were desired, the only common solvents in which ECA is soluble are MEK, acetone, nitromethane and methylene chloride, each of which is defined by law as a hazardous organic solvent and is required to be listed as a hazardous substance on the MSDS for any product that uses them as a solvent. If they aren't on the MSDS, then the ECA formulation has not been diluted and it does not contain them.

The MSDS for the two formulations under discussion only list ECA as sole the hazardous organic content. If the formulation was anything other than pure ECA or gelled ECA then one of the previously cited organic solvents would be required in the mixture and by law it would have to be listed on the MSDS. Neither MSDS lists an organic solvent, hence the product formulations can be deduced as being purified ECA.

From a practical standpoint, a diluted ECA mixture is impractical and undesirable for use in the "Krazy Glue" application as the viscosity of the diluted liquid is too low, which would result in runaway as the product is applied to the substrate being glued. Commercial ECA preparations go the other direction -- instead of thinning out a pure ECA formulation with a solvent, they either use pure ECA which is somewhat viscous, or they thicken the ECA formulation by creating a colloidal suspension with pyrogenic silica to make it highly viscous and easier to handle. High viscosity keeps the glue where you put it. It's why Krazy Glue gel will form a beaded droplet rather than running off of the workpiece like a drop of water, MEK, acetone, etc.

I'm sorry, but your assumptions that the two brands of ECA were different was based upon unsupported speculation and not organic chemistry.

[Mick Bailey]

The same chemical. Not necessarily the same quality, purity, viscosity, bond strength, specification compliance, cure-time, traceability, substrate-adhesion, shelf-life, activator response etc.

Industrial products have to meet defined criteria and have published specifications. A critical assembly may have time and handling constraints that need predictable, repeatable results that don't matter from a DIY perspective. I've used Loctite activator/primers with Loctite products and the results are consistent. With high-street superglue I get foaming, excess blooming, overheating, embrittlement and other issues. This alone suggest there is a difference in the composition of the respective adhesives. Industrial products have published specifications that are achievable in a production environment.

Contaminants in the base materials, processing, or post-process environment can play a big part in bond strength and can impact on curing and shelf-life. I wonder if the manufacturers of £/$ store products meet the same quality acceptance criteria as Loctite or some other industrial product.

[bob p]

At the molecular level, two samples of the same pure chemical will, by definition, have physical properties that are identical. It's not possible for the physical properties of two samples of the same chemical to be different unless one sample is contaminated or the samples are comprised of two different chemicals. The physical properties of the chemical itself, such as melting point, boiling point, vapor pressure, viscosity, etc. are CONSTANT. As in INVARIANT. They're so constant that the reference values are published in the CRC Handbook of Chemistry and Physics. (You'll need a subscription to look them up.)

Handbook of Chemistry and Physics 98th Edition

If the chemical is pure then all of it's physical properties are going to be consistent. So what's the difference that makes the industrial-grade products special? It's the special attention that is provided to the product by the seller. Commercial products have to meet defined criteria and they're guaranteed to have a stated level of purity, there is traceability in their provenance, there are tighter controls on freshness, storage, and much better packaging. And they go through a process of grade certification and that adds to their cost. You don't get that with the 99-cent tube of generic ECA.

Packaging is significant. the 99-cent tube of dollar store ECA is made as cheaply as possible. The tube is not designed to eliminate bubbles, it foams, it drips, and it cannot be resealed well enough to prevent degradation of the product after it has been opened. The result is that a tube of generic ECA typically squirts out a mess. It can't be effectively resealed so it gives you one application and then it's dried up by the next time you go to use it. In contrast, the industrial preparations have much better packaging that's designed to eliminate bubbles, foaming, drips, provide consistent application and can effectively be resealed. Those qualities lead to improved success and prolonged service life after opening, even if the formulation in the dispenser is the same.

There are many factors that make the 44-pound tube of glue cost 61x more than the 99-cent tube. Formulation isn't necessarily the biggest difference.

It would probably surprise people to know that there are not a lot of manufacturing lines making specific specialty chemicals in the US. Even once a product goes off patent, in most circumstances chemicals like this are made by only a handful of suppliers, with intermittent production runs and consistent sales into the secondary market. One production run ultimately leads to huge amounts of product, and packaging of the chemical from the same production run under a variety of brand names. The formulation of the lot ends up being the same, though different grades may be assigned to sublots depending upon the how those specific subplots are packaged, handled and assayed to provide the types of guarantees that were mentioned previously. All of those grading certifications cost money. Here in the USA the supplier of ECA for LocTite is Henkel North America. In addition to selling it's own name-branded products Henkel also sells their chemicals in the secondary market.

in the big scheme of things, most of the difference in the different ECA products isn't based on formulation per se, it's based on packaging and ancillary certifications that are provided for the product.

Putting this into it's proper perspective -- none of us are manufacturing mission critical components. If the OP wants to secure a lifted trace back down to the board, both the $61 tube of Loctite and the 99-cent tube of Krazy Glue would do the job. My experience is that Krazy Glue holds a trace down pretty well, at about 1/60th the price of the Loc Tite branded product linked previously. But it is indeed a PITA to work with.

> I wonder if the manufacturers of £/$ store products meet the same quality acceptance criteria as
> Loctite or some other industrial product.

They may meet the same quality criteria, but of course they don't guarantee them at the lower price. When you buy the dollar-store product you're getting the cheapest packaging possible, with none of the ancillary certifications. When you buy the Loctite branded product you are buying a value added product, and paying for things that are not being sold with the dollar-store generic product, which go beyond the formulation of the chemical itself, like a brand name's guarantee of quality and presumably other characteristics such as guaranteed performance specifications, a guarantee of a high degree of purity, guaranteed freshness, support from your factory representative, etc. At most, you might get a guarantee of a 99-cent refund if the dollar store product is "bad", but the formulation should not be expected to be any different. ECA adhesives are typically sold as non-diluted ECA. When you buy the name brand you're paying for a lot more than just the chemical in the tube.

[J M Fahey]

Long ago I tried using Loctite or Hernon "speaker glue" to assemble my own, but results weren´t good enough, at least in heavily abused Guitar speakers.
One of them was black and boasted of having black rubber microspheres in suspension.
Went back to old reliable oven cured Industrial Epoxy.

[g1]

The MSDS are not some secret, so I'll share them. If we're going to discuss them perhaps they are worth a glance?
My eyes may be old and tired, but they seem to list different ingredients. In any case, it seems a bit of a stretch to call the two the 'exact same formulation'.

[Mick Bailey]

MY understanding of MSDS is that it is not an ingredients list and non-hazardous chemicals are not required to be listed. There are also thresholds for hazarous chemicals below which their listing is not mandatory, and a lower threshold for carcinogens. Even so, the listings usually (but not always) present the composition within a range, such that with two seemingly identical products their ingredients could lie at the extremes of their respective ranges and therefore perform differently.

I bet the OP wonders what happened to his original question. Maybe Elvis has left the building.

[bob p]

Oh yeah, Elvis left the building a long time ago! My apologies to the OP for the hijack, but that’s the norm around here once a thread achieves a critical number of posts. But I’m happy to keep the chemistry hijack going if anyone is interested…

In response to Mick’s comment about the MSDS, he’s 100% correct – it’s not an ingredients list or a recipe. It’s a list of hazardous chemicals in the product that people need to be aware of. And as we’ll find out in looking at the latest 2 data sheets that have been posted, a hazardous chemical can be present in very small amounts ( on the order of 0.1% ) yet it’ll still be required to be listed on the MSDS.

Kudos to g1 for posting those two additional data sheets. They shed some light onto the discussion that the original data sheets that have been the subject of this discussion previously, did not shed.

Specifically – the two MSDS that were originally cited in this thread showed a pure ECA products without listed additives. The conclusions drawn from them were correct – those products had the same formulations. That’s not a surprise, as ECA glues are monomeric liquids that form polymers when they get exposed to a nucleophile, which is typically water obtained from environmental humidity. It's common knowledge for anyone who's taken a college level organic chemistry course that their formulations do not require anything other than pure ECA for them to work as intended.

Now we have two new data sheets to look at, which list other ingredients. This is where it gets interesting for chemistry geeks.

Elmer’s Crazy Glue:
0.10% 2,2'-Methylenebis(4-methyl-6-tertbutylphenol)

Loctite 382:
0.10 to 1% Phtalic anhydride
0.10 to 1% hydroquinone
0.10 to 1% 2,2'-Methylenebis(4-methyl-6-tertbutylphenol)

These additives are interesting. We can discuss what each one of these individual additives does, if anyone is interested, but I won't go there unless someone asks. Just in case someone doesn't ask, here's the spoiler: none of these additives are directly incorporated into the ECA polymerization reaction that provides the adhesive properties and structural stability of ECA glues. They aren’t part of the adhesive properties of the product, which is 100% based on ECA polymerization, so the additives can be considered irrelevant when it comes to bond strength.

Instead, these additives act as preservatives, like BHA and BHT that get added to a loaf or bread, which acts to prolong the product’s shelf life without changing the nature of the product itself. They don’t exist in sufficient quantity to have an effect on the issues that Mick was concerned about: bubbling, foaming, viscosity, blooming, embrittlement, heating, etc., but they clearly show that the Loctite 382 product is a superior formulation that will have a longer shelf life than Crazy Glue. Will it result better workability or stronger bonding? Bonding, no. Workability? Maybe. One of the additives is actually used to effect the speed of the ECA polymerization reaction without being directly incorporated into the ECA polymer itself.

I know we have at least one other chemist on the board, but I don't remember who it is. Maybe he'll chime in...

[ralphonz]

Haha. Elvis would have left but someone glued him down...

I do plan on posting here again re the original topic once I've had a chance to explore the problem further I'm afraid other things have gotten in the way.

You'll be glad to know I did not buy any glue (yet!)

[ralphonz]

I'm new here so pardon me for being cheeky and asking the discussion about glue happen on another thread though if that's doable! I'm trying to diagnose an amp and instead find my self pondering the chemical make-up of adhesive! I had not expected that

[bob p]

Elvis has definitely left the building on that one, sorry.

Your request does not sound unreasonable, but the way things work around here hijacks are so common that we just grin and bear it. it would take so much effort to clean up all of the threads that we just live with it for the most part.

[ralphonz]

Fair doos I'll just have to live with the scrolling and thoughts about adhesive! Worse things happen at sea.

[Enzo]

In our defense, we have resisted the temptation to talk about bringing charcoal to Newcastle.

[bob p]

But why? If you think of it when you're reading this thread then it's fair game.

[g1]

ralphonz, sorry about the tangent we are off on here, if you can bear with us a little more, I assure you we'll get back on track when you get back into the amp.

The datasheet that implied the loctite was pure ethyl-CA was not the MSDS, but a 'technical data sheet' which I imagine was only concerned with the most active ingredient.
I could not see how a flexible CA could be the exact same formulation as the brittle stuff, nor could I believe Loctite was simply gouging; thus my objection to the idea they were the exact same product (just at radically different prices).
I am interested in what gives it flexibility.

I think tedmich was the other member here working in chemistry, so I've flagged him and hopefully he will shed more light on the issue.