brittle silicone conformal coating

[coppercone2]

I put MG chemicals silicone brush on conformal coating on my welder PCB 24 hours ago, today I gave it a shot and its freaking brittle. If I run tweezers on it, it flakes off like molten sugar.

I thought it should be like... hot glue or something. Why did this stuff get so brittle? Bad product? Am I doing it wrong? I know maybe the cleaning was not done perfectly.. but I thought it would peel off, not crack off, even if poorly adhered.

I had some drip on the table I was working on too, and it was pretty brittle. I was expecting like a gel.


It does say it contains acrylic, but it seems kinda... weak and flaky. 

I think I used the same one last year, and on the underside of one of the PCB it flaked all off, on the main board. I thought it had to do with bad cleaning maybe, this year I spent 1/2 a can of solvents to basically hose it down, and then dried it with heat for a while.



If I have to do it again maybe I can use q-dope or something, because it seemed to work for me, but I did just buy and apply this stuff. Its probobly g oing to stay on until something breaks again because I had it with this mother fucking goop on my mother fucking board



I have a window sealer silicone, that flows well, and it cures into a rubber type substance. But this cures brittle, even on a piece of steel that it dripped on. Is this supposed to happen? Its crummy.

[tooki]

Which exact product did you buy? Part number, please.

MG sells true silicone conformal coatings, but I doubt you have one of those because they’re only sold in large containers. The one sold as brush-on  in smaller packages is #422C silicone-acrylic blend, though depending on where you look, it’s labeled as “silicone+modified acrylic”, “acrylic-silicone blend”, or just “silicone conformal coating”.

I’m no expert on conformal coatings, but I assume thorough cleaning is essential for proper adhesion. The instructions certainly say so.

The conformal coatings catalog seems potentially contradictory to me: they describe the silicone-modified acrylics (422B and 422C) as “soft and flexible”, but the table of specifications says “pencil hardness (ABS): F, hard” for them. I had to look up what a pencil hardness test is, but apparently it’s a way to test the hardness of thin films by the effect of a pencil lead pushed into it: see https://kta.com/kta-university/measuring-hardness-applied-coatings/
and https://www.micomlab.com/micom-testing/astm-d3363/

I assume the ABS means that this is tested with the coating applied to ABS plastic.

What isn’t obvious to me is whether this means an F pencil is sufficient to cause damage, or whether it means it can resist an F pencil.

Have you considered, ya know, contacting MG Chemicals?

[coppercone2]

ima contact them sunday holiday weekend when I bought it from amazon, that will work out well. someone who knows anything won't be back there till wensday probobly 

Some it dripped on a table. I can scrape it off the table and then break the puddle in half like its molten sugar.

its the modified acrylic one

the material is brittle when it dries. its not like any silicone I have seen at all.

[coppercone2]

do you have a receipt? No.. well I am going to go into CYA mode, just in case, I won't actually try to communicate meaningfully.

The person hired to deal with business to business communications will be useless for this purchase. I don't bother

Lets say I got a bad batch. But its from the wrong vendor, then the manufacturer basically has the option to dodge a bullet by claiming its counterfeit. Its in their interest not talk to me, unless they want to be responsible for a recall. Maybe out of 10000 people I am the only one that noticed, that's what they normally hope for, so you get stone walled. Then suddenly talking to me means making or breaking $300k , so its basically useless unless you feel like going out on a limb and pressing them.

Meanwhile someone here might have been using this regularly and can tell me what is actually going on

[tooki]

ima contact them sunday holiday weekend when I bought it from amazon, that will work out well. someone who knows anything won't be back there till wensday probobly 

Some it dripped on a table. I can scrape it off the table and then break the puddle in half like its molten sugar.

its the modified acrylic one

the material is brittle when it dries. its not like any silicone I have seen at all.

Is there some reason you can’t answer the simple question:

Which exact product did you buy? Part number, please.

I didn’t ask that to hear myself type. I asked because they have multiple silicone modified acrylic ones (I listed them both in my post).

[tooki]

do you have a receipt? No.. well I am going to go into CYA mode, just in case, I won't actually try to communicate meaningfully.

The person hired to deal with business to business communications will be useless for this purchase. I don't bother

Lets say I got a bad batch. But its from the wrong vendor, then the manufacturer basically has the option to dodge a bullet by claiming its counterfeit. Its in their interest not talk to me, unless they want to be responsible for a recall. Maybe out of 10000 people I am the only one that noticed, that's what they normally hope for, so you get stone walled. Then suddenly talking to me means making or breaking $300k , so its basically useless unless you feel like going out on a limb and pressing them.

Meanwhile someone here might have been using this regularly and can tell me what is actually going on

Nobody likes a preemptive rant, where you’re bitching and meaning before you’ve even given the company a chance.

It’s one thing to ask if anyone here happens to have experience with the product. But it’s quite another to be badmouthing the company before you’ve even reached out to them! 

[coppercone2]

some of their products are utter shit.

The deoxit "Fancy" spray caps (conspiracy to make you buy more deoxit), the spray on conformal coating (bubble city), etc

I need to know  if this is one of them

if you used them, you would know

[tooki]

And now you’re ranting about a different manufacturer entirely! Deoxit isn’t an MG Chemicals product.

[tooki]

But even if we ignore that ridiculousness: if you want people’s experience with a particular product, you need to properly specify which product it is.

I’ve asked you TWICE to name the part number, because the description you keep giving IS NOT UNIQUE TO ONE PRODUCT THEY SELL.

This is like pulling teeth. There is absolutely no reason for you to be so evasive.

[coppercone2]

I will wait for something other then the neighborhood poltergeist that haunts my threads like its his task force job to complain

[tooki]

I will wait for something other then the neighborhood poltergeist that haunts my threads like its his task force job to complain

It’s frustrating to put real effort into trying to answer your question (which I very much did for the first reply) only to have you devolve into a self-sabotaging moron at the tiniest (completely reasonable) question, and then be insulted for trying to help.

At this point I hope no one else answers, even if they do know, because of your obnoxious attitude.

[glenenglish]

I use DCA. fairly flexible.

[coppercone2]

I use DCA. fairly flexible.

do you use this from a can? does it make tons of bubbles? The MG chemicals from a can just makes bubbles. manual brush Paint on it applies nice but its freaking brittle like molten sugar

[SMdude]

I use DCA. fairly flexible.

do you use this from a can? does it make tons of bubbles? The MG chemicals from a can just makes bubbles. manual brush Paint on it applies nice but its freaking brittle like molten sugar

Don't shake the can!

I have used various MG chemical coatings. The main one I use is an acrylic one, which does flake when you scratch it, but if you don't tamper with it it is perfectly fine.
I used a polyurethane coating from them and it was a much better, thicker, rubbery coat, however, you need to use the whole can fairly quickly or it will go off in the outlet tube and nozzle no matter how carefully you try and clean it up.
The acrylic can seems to be a lot more forgiving and better for smaller jobs.

[coppercone2]

the silicone one is brittle, i assume acrylic is even more brittle

[tooki]

I used a polyurethane coating from them and it was a much better, thicker, rubbery coat, however, you need to use the whole can fairly quickly or it will go off in the outlet tube and nozzle no matter how carefully you try and clean it up.

Did you try the trick of, after use, inverting the can and pressing the nozzle until only propellant comes out? That's standard procedure for many kinds of spray adhesives to prevent the nozzles from permanently clogging.