I need a glue that dries quickly enough to create a "bead" and dries clear.

I do NOT want to use glue attach anything to anything. I need to create a small clear pin-sized area that I can feel for, but which spectators won't spot.

If you've ever felt a card or deck of cards that has been "punched," that's about how visible the result should be. Except that I'm not working with cards here, I'm working with a small plastic surface (similar to a Lego brick). I need to mark one of multiple plastic items so that I can identify it by feel.

Glues that I have already tried, which do not work:
- Cyanoacrylate (Super Glue): dries too slow, creates a thin layer rather than a bead
- Model Cement: dries too slow, creates a thin layer rather than a bead
- Adhesive dots: the smallest size (6mm) is much, much too large and is too visible

I spent some time in this forum checking that my issue doesn't already fall under "asked and answered."

Does anyone have a suggestion?

E6000 is good. It has a rubbery texture when dry.

2 part Epoxy resin might work, although most 2 part epoxy sold to consumers spreads to coat the surface it sits upon as flat as it can, there are ways to coax it into taking shape...

If only they made epoxy putty that dried clear!

Thanks, gaddy! I'm not familiar with it. I'll try it out.

My experience with epoxy makes me want to try something else before I try epoxy. I don't remember it holding its shape particularly well. I could be wrong.

Is it possible that a small nick on the edge could work instead?

Cyanoacrylate (CA) would probably work for you if you use the right viscosity. A fresh bottle of thick CA should bead up and stay put the way you need. An older, opened bottle of medium CA could also work, because CA thickens up over time. You could also dump a blob of any CA onto a disposable plastic surface/container, leave it out in the open air, and stir and check it with a toothpick every so often until the CA reaches a consistency that you need. I wouldn't want to use a CA that is too thick/old or it will get kind of "stringy" when you try to pull your applicator tip away from the surface that you are applying the CA to. I would apply the CA with a toothpick, a disposable syringe, or straight from the bottle with one of those precision fine applicator tips.

Clear epoxy could also work, but viscosity is again key here. You would need to apply it at just the right time in its pot life when the viscosity is conducive to beading up nicely, but not too late in the epoxy's pot life that it gets stringy when you need to pull your applicator away. Another caveat: I've seen a lot of clear epoxies turn yellow over time.

You might also consider a UV cure glue. I've used Bondic a few times, it's clear, the viscosity is conducive to forming a bead, and you can fiddle with it all you want until you get the shape you need, then cure it in seconds with the UV light. I just tried a tiny dot of Bondic on a scrap of clear plastic, and it looks great. I don't know how optically stable this stuff is, though. I've heard that Bondic (and CA glue, for that matter) can also yellow over time, so you may need to re-do this eventually if some of your feeler bumps become more noticeable down the road.

Hope this helps!

Ross

Thick CA glue with an accelerator.

Yes, CA accelerator will speed the cure, I neglected to mention that. Beware that some accelerators can spray unevenly, which can cause ugly residue and/or uneven curing. I generally prefer the aerosol accelerators over pump types, but even some aerosol ones can spray poorly.

Regardless of what material you go with, I would test on scrap first.

No--but how I wish it would! I'd rather have avoided glue entirely.

The "feeling-point" is on a flat surface; a nick on the edge would be very visible.

Ross, this is immensely helpful! Thank you! This gives me plenty of avenues to try. I also saw your note about an accelerant. This whole concept is new to me, so it seems like I have some research ahead of me.

I do appreciate the note to test on scrap. That's what I was already doing, but others will read your splendid message who need the reminder. And let's face it, your reminder did me no harm.

I had faith that the Café had some people who really knew their glues, and you (and others) have stepped up. Many thanks.

Doug

Thank you--I didn’t know accelerators were a thing! I have some research ahead of me.

(I'm one of those people who is made happy by having research to do. )

Doug

Incidentally, for the benefit of people who will be reading this thread in the months and years to come, I tried the E-6000, and it has the same issues as Cyanoacrylate (Super Glue) and Model Cement.

Doug

If you have tried most glues, like magic I would think out of the box. I would try a drop of liquid band aid from the pharmacy section--- if I does not work you can just keep in your first aid kit.

Thanks--but here in Canada at least, liquid band aid is a thing of the past. In fact, although I can't speak to amazon.com, but even on amazon.ca it's a hard thing to find!

I'm currently working on letting the various glues I do have dry for varying amounts of time and seeing if it has any hold left. Results one I have them.

Did you tried this? They are available in different viscosity, For your need I would use a thicker one. You get them including a LED UV lamp.

Thinking a bit outside the box here... Perhaps with the glue still wet, hold another piece of plastic that is the same color over it and sand with sandpaper. Let the dust drop into the glue and let it dry.

Reporting in briefly...

I've not yet had a chance to try glue cured with UV. Nor yet a hardener.

I *love* to hear from people who think outside the box! Unfortunately, the object is so small and (ahem) uniquely surfaced that sandwich + sanding won't work.

I have a temporary solution that will get me through the next week; I'll return and work on a long-term solution after that.

For the benefit of others: I tried varying the dry times for the E6000 that gaddy recommended. The sweet spot seems to be 11 minutes. If I let it dry 10 minutes or less, it was still too liquid. If I let it dry 12.5 minutes or more, the consistency was very good--but it failed to adhere. It failed to adhere to such an extent that merely feeling for the glue caused it to detach.

So, starting with E6000 dried to the 11-minute mark, I applied an impossibly small amount used a rounded toothpick. Even the small amount is immediately obvious to the touch.

Of course, I believe strongly in fallbacks and backups, so I applied a second bit of glue to a second location. It looks a little less natural to feel the second location, but it's better than panicking because I can't find the telltale mark.

This is just to get me through the next week, as I said. I'll return to the long-term solution once I live through this upcoming week, which promises to be--how can I put this?--"differently paced".

Gorilla Glue now has a Clear glue that does not foam like the old one. I haven't used it yet, but I do know the older regular Gorilla glue holds great.

Tom

Another outside box thought... What if you were to use some tape, poke a hole in it, put your glue on that spot and when the glue has dried, remove the tape.

Never tried three grains of sand and a drop of cyanoacrylate?

My pleasure, Doug!

It was quite evident that you were already testing on scrap, but I added the caveat out of habit. My wife is an artist, and it drives me crazy when she dives into a new medium without testing it first. She once ruined one of her paintings with a new coating that she did not test first.

If you are a CA glue aficionado, you should definitely check out CA accelerators, they add a whole other dimension of control to CA glue. You can use it to prevent the migration of CA glue, e.g. put down a barrier of it to prevent thin CA glue from wicking into an undesired area. In my early model building days, we would mold small parts out of CA using crude molds made from Plasticine clay, after spraying the molds with CA accelerator, then pouring CA glue into the mold.

BTW, there are different ways to control adverse fogging with CA glues, best to Google that, if you find in testing that your CA glue is not curing as pretty as you'd like.

Thank you for sharing your progress!

Ross