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cthulhu

Cyanoacrylate vs. PVC solvent cement

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I've been using the Loctite professional cyanoacrylate (superglue) for Bones.

 

But, one thing I've always liked about toluene based model cement and the plastics it works with is the solid weld you get when it lightly melts the surface of the plastics. With proper pressure and fitting the melted surface can very neatly eliminate any join line.

 

With superglue and Bones I can come close to the same effect, but I was wondering if PVC solvent cement would take it up to the next level similar to model cement.

 

Has anyone tried using PVC solvent cement, such as the Oatey solvent cement used for PVC pipes? My biggest concern is that it would be too harsh for the Bones PVC and melt too much.

 

Oatey PVC Cement Experiment:

 

Components:

 

4 x sprues from Bones rats

1 x can of Oatey PVC cement - regular

1 x toothpick

 

3Sn6UkN.jpg

 

Application:

 

Application was pretty easy, and I used the applicator brush from the can. I simply raised it up and brought the component to the brush above the can.

 

HcNsiUp.jpg

 

Attachment 1, End Attachment:

 

I decided to try two combinations of attachment. The first is with a small part of the sprue combined at the back.

 

lXIGfqI.jpg

 

Closeup: Notice there is a little roughness. My first attempt I went too light with the glue and it didn't melt enough of the surface to form a good bond.

 

SQY0B2O.jpg

 

Attachment 2, Center Attachment:

 

My second test is attached at the back in the middle. I aligned the center marks, and applied glue between the left and right marks.

 

5PIuQ2O.jpg

 

Closeup:

 

TizIGto.jpg

 

I wanted to add a little more glue at the joint, so I applied with a toothpick:

 

Ls7jNv9.jpg

 

Cure Time:

 

Per the Oatey instructions the bond is dry to handle in fifteen minutes, but requires a two hour cure time before placing a pipe under pressure. Accordingly, I'll wait the two hour period before testing the bond.

 

Post Cure Appearance:

 

I forgot to take a picture after curing. However, most of the glue had evaporated leaving the joint solid. You can briefly see the appearance in the flexibility/center attachment test video.

 

Bond Test 1, End Attachment:

 

It didn't take much force to separate the pieces. There were two factors that could have impacted this. I attempted to bond this piece first, and when I didn't apply enough, I simply applied more. I should have probably removed the covering glue and reapplied directly to cause a greater melt between the pieces. You can see in the post test image that after separation much of the "Reaper" text is still visible, so there wasn't a lot of melt.

 

ihX6cgO.gif

 

Bond Test 2, Center Flexibility and Attachment:

 

Flexibility appears good without any cracking or other impedance. As for strength, this bond was much stronger than the first as it didn't suffer from re-application.

 

tqO5Lf4.gif

 

Post Test Appearance:

 

Test 1, end connected:

 

8BlFksY.jpg

 

Test 2, Center Connected: 

 

B8XKCcL.jpg

 

Overall:

 

I think the bond strength would be higher if I lightly sanded the areas to bond, allowing the solvents to penetrate deeper into the surface. The acetone present in the Oatey formula didn't create the melt I feared.

 

I will retest now with Cyanoacrylate and do the same strength tests, although even if the Cyanoacrylate is stronger I still prefer this method of bonding as it is more permanent. As the Cyanoacrylate ages it will weaken and separate, and I don't believe a solvent weld will suffer the same fate.

Edited by cthulhu
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Maybe try on some sprue?

 

or some broccoli that you have clipped of a mini in prep for a new base?

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I have tried something similar -- vinyl repair cement. The post on it is here:

 

http://forum.reapermini.com/index.php?/topic/48668-bones-preparation-glues-putties-mould-lines-etc/?p=1127711

 

The active solvents in it are MEK and tetrahydrofuran, with a clear vinyl filler material. It seems to work the same way as model cements, bonding by slightly melting the facing surfaces together.

 

I've used it on about four medium-to-large models now with success. I like it because it provides a flexible joint that is resistant to cold and heat, unlike CA glue.

 

Another idea might be to try a model cement that welds Butyrate or ABS plastics, like Plastruct Cement. That (desirably) might not be as harsh as the PVC pipe cements.

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I have tried something similar -- vinyl repair cement. The post on it is here:

 

http://forum.reapermini.com/index.php?/topic/48668-bones-preparation-glues-putties-mould-lines-etc/?p=1127711

 

The active solvents in it are MEK and tetrahydrofuran, with a clear vinyl filler material. It seems to work the same way as model cements, bonding by slightly melting the facing surfaces together.

 

I've used it on about four medium-to-large models now with success. I like it because it provides a flexible joint that is resistant to cold and heat, unlike CA glue.

 

Another idea might be to try a model cement that welds Butyrate or ABS plastics, like Plastruct Cement. That (desirably) might not be as harsh as the PVC pipe cements.

That sounds similar then to the Oatey regular duty PVC cement like the kind found in Home Depot & Lowes.

 

MSDS says Oatey is:

40-60% Tetrahydrofuran

10-25% Acetone

12-20% PVC

5-15% Cyclohexanone

5-15% MEK (Methyl ethyl ketone)

 

Comparing that to the MSDS for Dritz' Instant Vinyl:

65-75% MEK (Methyl ethyl ketone)

10-20% Tetrahydrofuran

1-5% N,N-dimethylformamide

 

I agree that I like the idea of a flexible welded joint as opposed to CA. I have some miniature from 20 years ago that the CA has lost it's hold on... and these were not high use minis.

 

The Oatey PVC cement isn't very viscous, but I think it could be thinned with regular acetone from Home Depot as well, and I think one small can would be close to a lifetime supply.

 

I also found what Oatey calls general purpose PVC cement which looks closer to Instant Vinyl than the regular Oatey PVC cement:

30-45% Tetrahydrofuran

8-18% MEK (Methyl ethyl ketone)

10-20% Acetone

8-15% PVC resin

3-7% CPVC resin

10-20% Cyclohexanone

1-5% Fumed silica

Edited by cthulhu
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Maybe try on some sprue?

 

or some broccoli that you have clipped of a mini in prep for a new base?

Good idea.

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Interesting... the Oatey PVC cements might be "hotter" than Instant Vinyl, what with the acetone content.

 

One usability problem I can see is that the Oatey cement comes in a 4 oz or 8 oz can. You'd need to sacrifice an old brush or transfer it to a small applicator bottle to use it.

 

I'd be very curious to see how the Oatey works for bonding Bones. If you do try it, post the results you get...

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Maybe try on some sprue?

 

or some broccoli that you have clipped of a mini in prep for a new base?

 

Good idea.

The sprues from the rats, kobolds and goblins from the Reaper Kickstarter I core set provided a good amount of test material.

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Maybe try on some sprue?

 

or some broccoli that you have clipped of a mini in prep for a new base?

Good idea.

The sprues from the rats, kobolds and goblins from the Reaper Kickstarter I core set provided a good amount of test material.

 

Yup. I have them... I just don't remember if I clipped them or not. Hopefully I didn't.

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Interesting... the Oatey PVC cements might be "hotter" than Instant Vinyl, what with the acetone content.

 

One usability problem I can see is that the Oatey cement comes in a 4 oz or 8 oz can. You'd need to sacrifice an old brush or transfer it to a small applicator bottle to use it.

 

I'd be very curious to see how the Oatey works for bonding Bones. If you do try it, post the results you get...

The can I had in the garage from the last time I worked on our sprinkler system is gummy, so I'm going to head out to Home Depot and pick up a new can and some MEK to thin it. The MEK will reduce the ratio of acetone a bit and might make it a little cooler.

 

Since I started using the Tamiya model cement vs. Testors I've found that I really favor the thinner solvents, and I'm thinking it will be the same with this approach.

 

I'll post results later today.

 

Update:

 

Picked up the Oatey regular PVC cement. Didn't pick up the MEK because the Oatey was thinner than I remembered. The viscosity is more like Tamiya rather than the Testors.

 

Also, heat wasn't a problem. In fact, even hotter might be better. I'll update the original post with results.

Edited by cthulhu
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Remember, it isn't science unless there are explosions!

 

Other things to test:

 

How much does the glue melt or craze the surface? Put some on the sprue lettering, wait a little and wipe off.

 

How much filler material is in the cement? Put some on glass or a ceramic tile and let dry.

Edited by Grumpy Cave Bear
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Interesting... the Oatey PVC cements might be "hotter" than Instant Vinyl, what with the acetone content.

 

Also, heat wasn't a problem. In fact, even hotter might be better. I'll update the original post with results.

My bad. I didn't mean actual heat. I meant "hotter" in the sense that acetone is a stronger solvent than MEK -- it'll dissolve dried CA glue more quickly. Acetone will also turn a submersed Bones part to slime in a few minutes, to my dismay.

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Interesting... the Oatey PVC cements might be "hotter" than Instant Vinyl, what with the acetone content.

Also, heat wasn't a problem. In fact, even hotter might be better. I'll update the original post with results.

My bad. I didn't mean actual heat. I meant "hotter" in the sense that acetone is a stronger solvent than MEK -- it'll dissolve dried CA glue more quickly. Acetone will also turn a submersed Bones part to slime in a few minutes, to my dismay.

 

We meant the same. A small amount didn't have much heat... didn't melt the surface much... at least not as much as Tamiya or Testors on polystyrene. I had to use a larger amount to get the same heat as Tamiya on polystyrene.

 

I was worried about the Acetone content, but it turned out not as bad as I feared.

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How much does the glue melt or craze the surface? Put some on the sprue lettering, wait a little and wipe off.

 

I didn't specifically test this, but I did take some photos of the end connection after separation. The two joined pieces had lettering inside the join, and you can see that even after separation the lettering is still visible.

 

How much filler material is in the cement? Put some on glass or a ceramic tile and let dry.

 

According to the MSDS it is 12-20%, and I'd say that corresponds with the remainder in the joint.

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The test worked pretty good. I suspect that you'd get even better bonding if you clamp the pieces together and leave them to fully dry overnight, as I do. Washing and roughing the surfaces also helps.

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