How to glue to different types of plastic?

[Coronasan]

These plastic lids just don't seem to take my usual glues.



I am trying to stick bits of plasticard to these deodorant can plastic lids. These are quite flexible so I have be careful so the lid will not bend, that just causes anything stuck to it to drop off. I am going to pack the lid with foam board bits to see if that helps.

The surface of the lid does not take glue very well. Superglue is quite brittle and Contacta can't cope very well either.

Any suggestions from LAFers?

[Connectamabob]

Check the recycle codes, if they have any, to find out what kind of plastic it is. It's probably nylon, polypropylene, or polyethylene. These are non-polar plastics, meaning their molecular structure doesn't allow most types of chemical bonding. Makes them useful for industrial and solvent-resistant applications, but kinda sucky for modeling with, as they tend to reject glues and paints.

AFIK, there are three ways of tackling them:
1) Give the parts a good rough sanding, so there's enough tooth for a mechanical rather than chemical bond.
2) Flame treat the plastic. Basically wave a torch over the surface only just enough to make the surface sheen change, but not enough to melt it. The idea is you're oxidizing the surface slightly on a microscopic level, changing the chemistry to creating a polar surface layer that stuff can chemically bond to.
3) Special surface prep chemicals (sort of like primers) that either can bond to non-polar plastics, or change the surface chemistry in a way similar to flame treatment.

Sanding is the most accessible to the hobbiest, but is the weakest. Non-polar surface prep chemicals are probable the easiest, but are kinda expensive. Flame treatment supposedly works well, but seems like it would take some skill/practice to apply without risking ruining the part.

[Coronasan]

Check the recycle codes, if they have any, to find out what kind of plastic it is. It's probably nylon, polypropylene, or polyethylene.

Thanks, who would think that all these type of plastic exist to frustrate a scratchbuilder...

I can't see a code on the plastic lid, unless it is microscopic.

I will try sanding...

[Hammers]

Check the recycle codes, if they have any, to find out what kind of plastic it is. It's probably nylon, polypropylene, or polyethylene. These are non-polar plastics, meaning their molecular structure doesn't allow most types of chemical bonding. Makes them useful for industrial and solvent-resistant applications, but kinda sucky for modeling with, as they tend to reject glues and paints.

AFIK, there are three ways of tackling them:
1) Give the parts a good rough sanding, so there's enough tooth for a mechanical rather than chemical bond.
2) Flame treat the plastic. Basically wave a torch over the surface only just enough to make the surface sheen change, but not enough to melt it. The idea is you're oxidizing the surface slightly on a microscopic level, changing the chemistry to creating a polar surface layer that stuff can chemically bond to.
3) Special surface prep chemicals (sort of like primers) that either can bond to non-polar plastics, or change the surface chemistry in a way similar to flame treatment.

Sanding is the most accessible to the hobbiest, but is the weakest. Non-polar surface prep chemicals are probable the easiest, but are kinda expensive. Flame treatment supposedly works well, but seems like it would take some skill/practice to apply without risking ruining the part.

Man... You are *good*!

[DintheDin]

Man... You are *good*!

I second that! Very instructive info! Thanks for sharing!

[dbsubashi]

http://www.ironhands.com/construc.htm

My go-to guide for gluing. Though as Sean says, nylon is a pain to work with.

[Coronasan]

http://www.ironhands.com/construc.htm

My go-to guide for gluing. Though as Sean says, nylon is a pain to work with.

Thanks, that is a good guide. From the descriptions, I would guess my pesky lids are nylon...