CA vs Epoxy

[redboat219]

I'm contemplating on whether to use slow drying extra strength epoxy ( ACE brand rated strength 1900 PSI )or just ordinary thick CA to attach my Kilo resin fittings. I want a strong and durable bond. I read that CA has poor shear resistance.

[He Who Shall Not Be Named]

Go with the CA

[redboat219]

"By your command"

[Kazzer]

If you can afford to wait overnight use an epoxy. It's overall bond strength is greater than CA. I have found CA to be less 'elastic' & brittle, and the joints snap off easier. If you have large gaps, the Ca doesn't fill as well either. I am not familiar with ACE epoxy. Do you know what the hardener is? Amine curing is more commonly sold, and is perfectly adequate for this job. Make sure you sand the surface with coarse sandpaper to provide a key on BOTH mating surfaces. By mixing Cabosil (a lightweight filler/powder) you can create a gap filling paste without losing much strength.

[redboat219]

Anybody know how well epoxy bonds with styrene?
Anyway, here's a tip I picked up from Finescale Modelers worth trying when trying to attach resin parts to styrene models.
First attach a thin piece of styrene to the attachment face of the resin part using CA.
You then use solvent cohesives like ProWeld to attach the resin-styrene part to the styrene model.

[Subculture]

I find the acrylic adhesives like Deluxe materials 'Fusion' are really strong for adhering resins, metals or dissimilar plastic to plastic. Not only that, but the finished joint is sandable, cures rapidly and is fully waterproof. Quite a strong odour though.

[Kazzer]

Fusion sounds like a solvent. If so this is a true weld and is the best way to bond two styrene parts together. Imaging two blocks of ice, place them together, then pour water over the joint. It will melt the surface of the blocks, but then freeze again, turning the two block into one - a true weld.

Redboat219 saya "First attach a thin piece of styrene to the attachment face of the resin part using CA. You then use solvent cohesives like ProWeld to attach the resin-styrene part to the styrene model. "

This bond is only as good as the CA, which is brittle. Personally, I can't see the point, why not just use the CA and bond the original part. Better still, use epoxy on dissimilar materials. Solvent weld will only work on thermoplastics. See my article Adhesives and Fillers used in Model Making.pdf

[Subculture]

Nope, it isn't a solvent. it's a two part acrylic glue. Expensive, but one of the best I've ever encountered for glueing bits and bobs together.

Third product down on this page-

http://www.deluxematerials.com/products_spa.html

For very high stress areas you can use a bit of glass fabric reinforcement, but I've never had to do this.

[Kazzer]

Interesting! It looks like a Belzona product I used to sell called Mouldable Wood, that had a powder activator. Do you have an MSDS? I'll bet that would give a better idea. I still don't think it would perform as well as an epoxy, and 'acrylic' is a little vague (perhaps a red herring?)

[Subculture]

Sorry, I can't be more specific than that. The website doesn't have a data sheet, and the instructions aren't specific on what it is. it smells like acrylic.

I had a chat with a salesman a few years back on the deluxe materials stand. They sell epoxy too, so there was no need for them to sway me one way or t'other, but he told me Fusion was the glue to use for submarines.

I'm sure there are some instances where epoxy is going to offer an improvement, but for model submarines, I can't imagine where.

[Kazzer]

I had a chat with a salesman a few years back on the deluxe materials stand. They sell epoxy too, so there was no need for them to sway me one way or t'other, but he told me Fusion was the glue to use for submarines.

I'm sure there are some instances where epoxy is going to offer an improvement, but for model submarines, I can't imagine where.

In the interests of 'science' I put in a request to Deluxe Materials Ltd for an MSDS on this product. My first concern is that this material sells for (75cc) £14.50or $309.94 US per liter or $731 per US gallon. I suspect this would qualify for a motive to persuade. (Sorry to be such a damp squid or rain on your parade Andy). A good epoxy, in small quantities (always a HUGE factor) will run about $100-150 a gallon. So lets see what magic they've come up with for that price, if indeed they are prepared to disclose anything on an MSDS. Phew!

[Subculture]

DELUXE MATERIALS FUSION a high strength acrylic adhesive for combinations of GRP, wood, plastic, metal, epoxy, polyester, PVC, styrene, carbon fibre, acrylics and ABS. It is a liquid powder system mixed 1:1 which sets very hard. Useful for bonding high stress parts, such as metal fasteners onto dry GRP.

I agree it's expensive, but I've always found epoxy difficult to finish, plus the viscosity is often high. With Fusion, you can adjust viscosity, and it sands just like a resin once cured.

[Kazzer]

There are many epoxies with lower viscosity, as diluent can be added. However, temperature is my favorite way of dealing with this. Taking the resin to 85-90 degrees by placing the mixed container in hot water will turn the liquid to a watery viscosity in seconds. Downside is that for small quantities, you waste a little, but compared with the price of this Fusion, I personally wouldn't worry about that. The viscosity can also be adjusted by using Cabosil, which also makes this material very easy to sand etc. Another advantage of epoxy is longer working life, giving 15 mins to set and an overnight ambient temperature cure.

I would only use epoxy if I were bonding different materials together, so any styrene resin parts would be welded with a solvent like Pro-weld.

[Subculture]

Well okay, we can keep on going round and round like this ad naseum. The facts are this-

I do and have used epoxy.

I do and have used fusion.

There are areas where the two products cross over, like many adhesives, but I prefer fusion for a number of jobs especially where the joint is likely to be cosmetic.

Hang the expense, it's piffling when compared with the costs involved with the rest of the model.

[Kazzer]

Well okay, we can keep on going round and round like this ad naseum.

But this is good stuff for newbies and I have a personal interest in looking at new goops that come on the market. If it smells like freshly cut Plexiglas (Perspex) then I'll guess its a Methyl Methacrylate resin with a dry peroxide powder as the kicker. The other tub probably contains an inert filler. This would put it in the family of resins used to make counter-tops like Corian (filled with pretty stones) and windshield crack repair systems.

If the company comes up with a little more information, we'll easily be able to find out which family of resins Fusion belongs to, and maybe be able to recommend something similar on this side of the pond.