Question Can I use wood glue/v-nails on Polystyrene??

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LeMieuxGalleries

LeMieuxGalleries

CGF, Certified Grumble Framer
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Sep 24, 2008
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In the midst of a big move we put up a couple of Polystyrene frames that got ordered. I've never put one together before. Can I use my v-nailer and wood glue for a good hold? If not what is a quick fix?? Because I don't want to buy special glues or anything if i don't have to.

Thanks!


Jordan
 
Superglue can melt poly, which is kind of the point. You are actually making a welded joint. So be careful not to use so much as to let it ooze out onto the face or the joint will be ruined. You can v-nail as normal, just adjust clamp pressure so as not to crush moulding. Maybe place nails a little further in from the edge than for wood moulding.

advice is for the better high density moulding (usually dark in color) those lighter cream colored ones are usuall full of voids/air pockets and are the old style junk
 
V-nails work fine, but on a narrow moulding you can easily burst out the back if you get the nails too near the outside. Try a scrap bit before you join a frame.

As for glue, PVA is better than no glue at all and some poly mouldings are better at gluing than others. Again, try a bit. To really weld the corner, polystyrene cement as used in model making is the stuff. It's horrible and smelly though and (as prev ment) any stray glue on the face will spoil it.

You can make more economical poly cement with expanded polystyrene crumbs mixed with acetone. Use a very airtight jar and don't leave the lid off for long. :icon11:
 
Z David said:
Is superglue the glue of choice for joining polystyrene?



Z
Click to expand...

I use Plastibond. I buy it from Decor Moulding, but it's available from many sources.

plastibond1500_1_2.jpg
 
Less has several times
 
Z David said:
Is superglue the glue of choice for joining polystyrene?
Click to expand...
Superglue is one of the brand names for cyanoacrylate adhesive. Any brand will do, but one of the gel types generally works better than the more-watery types, because it does not run so much. As others have noted, be sure to keep the adhesive off the finish, because that would mar it irreparably.

I prefer to glue and vice the poly frames, and then v-nail them after the adhesive has cured for a few hours at least. That way, there is no need to worry about breaking the bond loose. If you glue and v-nail in one operation, any movement of the joint during early curing could break a bond, which would weaken the joint forever.

PVA and other water-borne glues are not recommended. Gorilla glue would work if you could keep it from foaming onto the finish, which would be very tricky. PVC pipe adhesive from the plumbing department of a home improvement store works, too, but not as well as cyanoacrylate.
 
Another advantage of first gluing and joining the joints in a vice, letting them dry and then v-nailing them is that you end up with a tidier joint on the outside. The joints are inclined to kick out a little on the outside if v-nailed immediately.
 
I too appreciate the information. I have yet used polystyrene, but I'm thinking about it for a particular job (regular) job!






Z
 
The appropriate glue for plastics has been debated here for years. My choice is that yellow glue used for black drain pipes - the plumbers stuff. $5 a can. Perfect for the application. I've used it on hundreds if not over a thousand frames in the past ten years.

Apply it with that fuzzy ball on the end of the metal rod. Keep the glue at least 1/8th of an inch away from the top edge, or it will squeeze out and destroy the finish. I apply it only on one face, and only on one corner at a time. Apply a thin coat.

V-nail away from the outside corner - start at least 1/2 inch away from the outer corner. Only once have I had a frame crack - the molding was stored outside below freezing, and it was too brittle.

Practise on some offcuts - glue a joint, wait ten minutes, then break it. The broken corner will be really ugly - the plastic stays glued, and the glued part comes away from the molding.

The manufacturer I buy it from sells to the big framing factories in Toronto - the ones that supply hotels, big boxes and starving artists selling sofa sizes. They mix a glue concoction of acetone and the powder that goes into the manufacturing of the moldings. They don't waste their time buying pipe glue.

If you have any questions, PM me and I'll send you my phone number. I can tell you more about plastics based on making every mistake in the book with the stuff. I've also made a lot of money with it.
 
That and more: these are the common mistakes:
- squeeze-out damaging the finish
- dripping glue on the molding
- touching the molding with glue on the fingers
- too few v-nails
- taking too large a bite on the Morso
- chopping too slowly on the chop saw
- inadequate support for larger frames when v-nailing

But on the whole, plastics have no warps or wows, there are generally fewer blems, and the larger ones look great and are extremely profitable. My supplier takes back all the offcuts to be added back into new stock. I've got a couple of profiles that sell amazingly well, box after box after box.
 
United has a product called PlastiBOND, item #U5074, comes in a 2 oz bottle, or you can order a larger size, the 2 oz last me usually several months. Easy to apply, then v-nail.....great bond, easy as the wood moulding..T
 
Just saw this post and have been joining Poly frames for months now on a large project. We have tested many glues and the Plastibond mentioned above is the best I have found. For those of you that want to be picky there are Chinese and European types of poly. Plastibond makes a glue for both. Just ask your moulding supplier which type you are buying. Omega, Decor and Universal are selling Chinese poly right now.
 
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