Adhesives for plastics

Having searched high and low, including some of our advertisers, and even Amazon, I am coming to the conclusion that I would stand a better chance of walking into Fort Knox and walking out with a bar of gold, than finding and purchasing a bottle or two of Ambroid ProWeld. I did find Tenax but I do not like the product because of the rapid evaporation rate and sometimes brittle adhesion quality. And those that did have the Ambroid don't seem to know when it will get restocked if at all. I like it because of it capillary effect and also because it does not mar the painted areas. I have read that Tamiya has a thin glue almost as good as the Ambroid but it appears to be another scarce commodity. I just received an order of some parts and had included a bottle of Plastruct's Weldene an newer product at least to me. Has no VOC's and has a pleasant citrus smell. I tested it on a couple of pieces of scrap styrene and it appears to have good capillary action and I have a tight bond that I cannot separate. May have to become my go to for now but I would still like my old reliable Ambroid if anyone knows where I can find it.

 

Just wondering, how long have you been contemplating ripping off Fort Knox?
Once again, I'll be following one of your threads. Sigh. I'm such a groupie.

 

Hey there is just four rows of barbed wire, razor wire, motion sensors. thermal imagers, lasers, and a few souls with the latest weapons with special night optics, and some mean dogs with big teeth that don't even like themselves. Got to be easier than trying to find a bottle or two of Pro Weld.

 

I keep seeing references to MEK which is the solvent, or used to be, for plastic plumbing pipe. The only contact I have had with that type of glue was a long time ago and I don't remember it being thin enough to have the capillary action and it dried with a purple color where the excess was.

 

I thought MEK was the core ingredient in Testors cement? Melts the plastic together.

 

The meanest one is called... Fluffy.

The first thing I thought about was Testors plastic model cement. It probably has the same adhesive but a different (and smellier) solvent.

 

I was a loyal Ambroid ProWeld user for years. However, the last time I visited my LHS, he didn't have it in stock. However, he did have Tamaya "Extra Thin" Cement. It seems to work as well as the Pro-Weld, so far so good.

 

From what little I have found it appears that MEK is an ingredient in a lot of adhesives. However since it was determined to be a bad boy it was essentially banned in a lot of substances that the general public use. The components vary in a number of adhesives resulting in different set times and in a few actual dissolved plastic is in the mix which gives a gap filling property like the gap filling ACC. The problem with Tenax is its very rapid evaporation and sometimes so fast that a complete bond is not formed resulting in a brittle joint. The Ambroid is or was slower to cure or evaporate thus allowing a better weld bond to form. What I liked about the stuff was the ability to use it on painted surfaces without disturbing the paint. For whatever reason the Ambroid penetrated the paint to the plastic. Yet when cured the paint would be left unharmed which meant that I did not have to be concerned about paint in the glue joint affecting the bond or have to touch up again.

I have read favorable comments on the Tamiya extra thin but the same issues with finding folks that carry it much less actually have it in stock. As stated earlier I did try some Plastruct Weldene last night. It has the same rapid capillary action I like, bonded in seconds , and 15 to 20 minutes later I could not separate the bond. It works only on styrene plastics and will not supposedly craze clear styrene like a lot of others will. So I will be giving it a try on my current project. Micro Mark has a adhesive that is called Same Stuff that supposedly works as well as the Pro Weld according to some internet sources.

And supposedly the home improvement stores sell the same basic stuff as Pro Weld in pint cans and case lots. Something I will have to check out the next time I am in a Home Depot around here. Some folks have stated that they are using that and just refilling their Pro Weld bottle from the pint container.

 

Hi John,

What is the product name of the stuff at HD?

I have not been real happy with the adhesives I've found lately.

thanks,
Dale

 

Regarding adhesives you may want to try connecting with a local acrylic/plastics house. They use a varied assortment of adhesives for such plastics as styrene, petg, acrylics. The stuff for styrene is the same stuff the hobby manufactures sell. They do produce items for various display company's, and have to assemble finished products. Before retiring I was a designer and CNC programmer for such a company that produced glued items from various sheet sizes up to 1.00 inch thick, and sheets as large as 51 x 100 inches. Just a suggestion. George

 

I don't know why MEK seems to have gotten a bad reputation.
It is not as bad as many solvents that were commonly used, like xylene and toluene.
MEK is a very useful solvent for lacquers and as an adhesive for plastics.

Anyway, to clarify your original issue:
Ambroid ProWeld is apparently methylene chloride.
Tenax-7R is 100% methylene chloride, so it should give exactly the same result as Ambroid ProWeld.
Micro-Mark's Same Stuff is also methylene chloride.
Tamiya Extra Thin Cement is an entirely different class of adhesive - 50% acetone, 50% butyl acetate.

One caveat - manufacturers are constantly changing formulas of paints and adhesives due to the myriad Federal regulations.
It is best to check manufacturers' specifications, which is where the above information is from.

 

I use the $1 cheapo tubes you can get at the dollar stores. It doesn't dry quickly, but a quick sniff tells me it's the real stuff, and it doesn't dry in seconds.

 

Call me old school, but I just use super glue or crazy glue on most stuff where it cant or wont be seen and let it dry. If I have something a bit heavy that needs to be glued down I will mix a small ball of a cheap two part epoxy I got from either Lowes or Home Depot, it dries up in about an hour or less, room temps. depending. Good Luck!

 

Reminds me of a time back in Nam when we held overnight at an outpost waiting for daylight to come back in. Shared a bunker with a dog called Satan, absolutely coal black and a disposition to match the color. Had made some good ole C rat hot chocolate. Turned back to get my cup and Satan had his snout buried in it. Since I valued the continued use of my hands it became his.

On the Testors if it is the same stuff I have used way back it is too thick for my use, unless they have a thinner version out now.

 

It was not named by brand on some of the discussion threads I checked or I just missed it. Whatever it is it needs to flow like water to have the needed capillary action. So tomorrow I will make a side trip when I am out to the nearest store and take my reading specs with me.

 

Are we talking about the stuff in the white and orange tube or the black squeeze bottle with the hypodermic needle tip?

I bet for all his meanness, Satan was your best buddy at night on the line in the foxhole, eh?

 

I have used the old Testors in the tube and the last I used was in a semi- square black plastic bottle. The stuff in the black plastic bottle was almost the consistency of the stuff in the tube.

Never did work with any of the dogs so it was just a chance encounter that I haven't forgotten. Never spent anytime in a foxhole. I was mostly in the boonies as part of a 4 to 6 man recon unit. When back in base it was either a hard framed tent or a bunker that had a marsten matcover with canvas over that and then about two feet of sandbags.

 

The stuff in the black bottle has changed then, the stuff I had was water consistency.

I've read quite a few accounts from Nam vets over the years as part of my history addiction. You recon guys are awe inspiring. Thank you for your service.