How to glue Mylanta?

[iamrohn]

I have a cutoff of a "Southwestern Green" (crushed turquoise) acrylic blank (from Woodcraft) and was experimenting with it... or hoped to. I discovered that a Mylanta oral liquid bottle is rather very much the same color and as luck would have it, we had an expired bottle in the cupboard!

My simple thought was to use the acrylic blank as a somewhat fat center band and then the Mylanta bottle as accents at the cap and tip (Mylanta-black-Mylanta). The majority of the pen would be cocobolo. Just 90 degree cuts, nothing fancy, but I thought this would look very sharp and I'm still excited for it, but...

I can't get the Mylanta plastic to glue. I've cleaned it well and scuffed it up. I've tried CA (thick) and after sitting (clamped) overnight it just knocks off. I tried Gorilla Glue (the bottle says "Original Gorilla Glue bonds virtually everything". Everything except Mylanta plastic because it too just let go after clamping it for 24hrs as the bottle says (and I did use water with the glue). In both cases the Mylanta plastic has no adherence to the wood or the black plastic I'm using (a non-identifiable take-out container).

I haven't tried Elmer's white just yet... it's the only other glue I have available without ordering something, which I'm willing to do - both ordering and trying Elmer's

Does anyone have any ideas on a glue I could find success with? I'm not ready to give up on this idea quite yet. I don't have a lot of experience with segmenting so I might be overlooking the obvious here also.

Thanks!

 

[Kenny Durrant]

I'm not familiar with the Mylanta bottle but I can tell you this. If it's made of HDPE your probably going to be out of luck. That's what they make casting molds out of and I haven't had anything stick to it yet. If it's not I wouldn't know what to try other than what's you've already done. Good Luck.

 

[magpens]

I suspect the Mylanta bottle material is polyethylene based .... devilishly , or perhaps impossibly, difficult stuff to glue.

Wish I could offer a constructive answer, but I will just follow along, hoping to learn something myself.

 

[monophoto]

Check the bottom of the bottle for the recycling notice. Its in the form of a triangle containing a number, and with an abbreviation for the name of the plastic below the triangle. That will tell you what kind of plastic you are dealing with. You can then do a web search for a table that identifies which adhesive works with which plastics.

Unfortunately, many very common plastics won't bond with any of common adhesives.

 

[iamrohn]

Check the bottom of the bottle for the recycling notice. Its in the form of a triangle containing a number, and with an abbreviation for the name of the plastic below the triangle.

Looking at the bottom... beneath the triangle... HDPE

Why would they make the bottle such a perfect match of color if it couldn't be glued?
Well... y'all saved me more time and accumulating frustration anyway.

Thanks for the help.

 

[magpens]

HDPE = High Density PolyEthylene

"If you flip over your bottle of laundry detergent, it probably has the number 2 imprinted, surrounded by a chasing arrow. That's HDPE's resin identification code. The code was designed decades ago to help get plastics recycling off the ground (although today community recycling programs are less likely to ask for plastics by the resin code number than in the past). "

 

[iamrohn]

My kid, the teenager, just said (with the superior tone of youth) to use PVC glue.

Who am I to blow against the wind? I'll try that later today... with his help

Sent from my Pixel 3a using Tapatalk

 

[magpens]

Searched for "How to glue HDPE" ....

 

[monophoto]

HDPE is notoriously difficult to glue - which is why it is often used to package glues.

Permabond has a polyethelene primer that they claim can be combined with CA to glue HDPE. I have no experience with it and can't comment on their claims.

There are also adhesives that are advertised as HDPE-specific glues - intended to glue HDPE to HDPE. My sense is that these are specialty products that might be hard to find, and it's not clear that they would work to adhere HDPE to wood.

 

[Mortalis]

My kid, the teenager, just said (with the superior tone of youth) to use PVC glue.

Who am I to blow against the wind? I'll try that later today... with his help

Sent from my Pixel 3a using Tapatalk

PVC glue works by dissolving the chemistry of the plastic and then allowing the chemistry to mix with the adjoining plastic chemistry. I will not work on plastic to wood adhesion. Good try though.

About the best suggestion I can give is to drill small holes in the plastic somewhere near just below the diameter that will be the end result of the turned blank. this will allow the glue to "penetrate" the plastic and bond to the substrate on the other side.

 

[monophoto]

About the best suggestion I can give is to drill small holes in the plastic somewhere near just below the diameter that will be the end result of the turned blank. this will allow the glue to "penetrate" the plastic and bond to the substrate on the other side.

There are several ways to skin this cat. Mort's suggestion is to create glue tenons that adhere to the wood on either side of the HDPE layer, and penetrate through that layer, pinning everything together. Traditional thinking is that the bond created by PVA glues is stronger than the wood on either side of the bond; however, the glue tenons created by this method will be very small, and making the HDPE layer thicker will reduce the strength of those glue tenons, so the question is whether there is a way to make that joint stronger.

I've gone through the mental exercise of imagining ways to cut the blank and then reassemble it using embedded dowels. But ultimately, it hit me that when pens are created by segmenting, most of the strength in the finished pen comes from the brass tube rather than the segmenting joints.

So I think the simplest approach to this problem might be to just drill the blank for the tube, cut it at the desired location for the HDPE layer, drill a tube-size hole in the plastic, and then glue the blank and HDPE to the tube. If the cut and glueup are done before the blank is turned to round, it will be very easy to reassemble the blank to align grain and get a tight joint. And if the two sections of the blank are securely glued to either side of the HDPE, the fact that the HDPE isn't securely glued to the wood won't matter.

The worst case might be that the HDPE layer (which will actually just be a ring after the pen has been turned) might be able to rotate around the tube. There is a solution for that - before gluing everything to the tube, use a craft knife to cut a notch in the side of the hole drilled through the HDPE layer. In the process of gluing the blank to the tube with the HDPE layer in place, that notch will fill with glue, and after it has cured, it will act as a key to prevent the HDPE from rotating around the tube.

 

[Mortalis]

I've gone through the mental exercise of imagining ways to cut the blank and then reassemble it using embedded dowels. But ultimately, it hit me that when pens are created by segmenting, most of the strength in the finished pen comes from the brass tube rather than the segmenting joints.

That was why I wasnt too concerned with the strength of the 'tenons' as you called them.

So I think the simplest approach to this problem might be to just drill the blank for the tube, cut it at the desired location for the HDPE layer, drill a tube-size hole in the plastic, and then glue the blank and HDPE to the tube. If the cut and glueup are done before the blank is turned to round, it will be very easy to reassemble the blank to align grain and get a tight joint. And if the two sections of the blank are securely glued to either side of the HDPE, the fact that the HDPE isn't securely glued to the wood won't matter.

I am afraid that not only will the piece of HDPE rotate, when the wood shrinks if will leave a noticeable gap between the three pieces.

The worst case might be that the HDPE layer (which will actually just be a ring after the pen has been turned) might be able to rotate around the tube. There is a solution for that - before gluing everything to the tube, use a craft knife to cut a notch in the side of the hole drilled through the HDPE layer. In the process of gluing the blank to the tube with the HDPE layer in place, that notch will fill with glue, and after it has cured, it will act as a key to prevent the HDPE from rotating around the tube.

See my reply above.

@monophoto 's idea is solid and if you are dead set on using that particular piece of plastic then perhaps 'V' slices around the ring of plastic just short of the finished diameter might be the way to go. I really do not think you need to be concerned about the strgtn of the 'tenons' though. I would suggest using an epoxy and not CA which is very brittle and the epoxy actually being a bit flexible.

 

[monophoto]

I don't think you need to be too concerned about wood shrinkage leaving a gap on either side of the plastic. Several reasons:
pens generally aren't turned from green wood, so if the wood is fairly dry, seasonal variations in humidity won't cause significant variations in dimensions. Also, shrinkage is mainly across the grain rather than with the grain; it is rarely necessary to worry about expansion/contraction along long-grain glue joints which is what this would be.

I agree with the suggestion of using epoxy for this glueup. I would normally prefer polyurethane when gluing pen tubes, but in this case, the foaming could create a problem with the plastic segment - I can visualize foam squeezing out between the plastic and the wood, and that would be a PITA to clean up!