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What is the best filler type adhesive for HIPS?


ship69

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Hello

 

What filler type of adhesive can you recommend for filling quite large gaps in 3mm Plasticard / HIPS styrene?

 

I am trying to avoid epoxy adhesives that come in 2 parts that you have to mix.

 

I have nonetheless jkust ordered some "Devcon Home 5 Minute Epoxy" (from here https://www.wonderlandmodels.com/products/javis-devcon-home-5-minute-epoxy/) but I don't really like using epoxy because I find it quite hard to work with.

 

[ Personally I find epoxy always tends to be rather too viscous and I find it hard to get it to flow into where I want it to go. And then if it is the quick setting type it will then go stringy which makes it hard to work with because it attaches to everything that touches it... and it will still take a while (e.g. 24 hours ) to cure properly and reach full strength. Also it's slightly hard to get mix the two components at exactly 50:50. I was recently using "1 minute" "Repair Power Epoxy / All Purpose" epoxy by Unibond but I found it starts to set way too fast, even though it doesn't reach full strength for c 24 hours. Hopefully the Devcon 5 minute stuff will give a more sensible working time. ]

 

What is the alternative to epoxy?  Ideally it mustn't drip slowly and it certainly mustn't shrink when it cures either. It would be good if it was clear too.

 

Many thanks

 

J

 

 

PS And where is the fastest place here in the UK to buy it from? Amazon was going to take a couple of weeks for delivery.

 

Edited by ship69
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2 hours ago, bmwh548 said:

Cut small strips of similar styrene, put them in the gap and then use some styrene filler over it. Let it dry, add more styrene filler if needed. 

Yes I was thinking of cutting strips of similar styrene and then jamming them in, and then paint over with some sort of cement (i.e. solvent!) to melt the surfaces together.

But what do you mean by "styrene filler"?

 

Either way cutting long, thin strips will be very time consuming as I have long, thin, tapering gaps. Also I'm not sure which cement to use.

I have:

1. Slaters MEK-PAK
2. EMA Plastic Weld3

3 "Mr. Hobby / Mr. Cements

4. Tamiya Extra Thin

 

 

2 hours ago, stevehnz said:

Milliput. I've not used it but heaps on here do for just this sort of task & it is something I really want to get.

Steve. 

 

Yes, Milliput looks interesting, even though it is still a two-part thing (i.e. an epoxy) that you have too mix. It looks relatively easy to handle by hand and it may not stick too badly to things when you handle it but it looks like it will be hard to get into a long, thin crack, no?  On the down-side it looks like you need to put some sort of chalk (dust/flour?) down to stop it from sticking to you work surfaces, plus it look like you need to use gloves when handling it.

 

J

 

 

 

 

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I can't answer those concerns but hopefully a milliput user will chip in & do so. I've doubts about needing gloves, people talk about using a wet finger to shape it & I guess remove excess, likewise I've read of it being used to fill wing root gaps & such like so it can obviously be shaped/rolled into long thin sausage shapes.

Steve.

Edited by stevehnz
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You get a bottle of cement (Tamiya, Gunze doesn't really matter), add small pieces of styrene inside (preferably styrene sheet, not old sprues), let it sit for a day or two and then you can use it as filler. The viscosity depends on how much styrene you put in. It's really good for filling gaps (thin layers though, you need to build it up) because after it's dry it has the same hardness as the surrounding plastic and it will react in the same way to sanding, rescribing, paint... 

If you're determined to use putty/filler you could try Revell as it dries hard and it has really good grip. On the downside it's a bit annoying to apply. 

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7 hours ago, bmwh548 said:

You get a bottle of cement (Tamiya, Gunze doesn't really matter), add small pieces of styrene inside (preferably styrene sheet, not old sprues), let it sit for a day or two and then you can use it as filler. The viscosity depends on how much styrene you put in. It's really good for filling gaps (thin layers though, you need to build it up) because after it's dry it has the same hardness as the surrounding plastic and it will react in the same way to sanding, rescribing, paint... 

Interesting suggestion. I am trying to get some styrene to dissolve in some Slaters MEK-PAK as I write this.  The main problem of course is that it shrinks in volume as the solvent evapourates. So as you say, you need to build it up in layers... and this is time-consuming!

I have also ordered some epoxy putty/filler (Milliput) however I fear that it will be too viscous to get down into the cracks properly.

Does Revell shrink as it dries?

 

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4 minutes ago, bmwh548 said:

All 1 part putties shrink. The 2 part ones (or epoxi) don't really shrink because those rely on the chemical reaction between the 2 components to harden, not on the evaporation of the solvent. 

Wait, I am no expert, but my understanding is that many 1-part adhesives/fillers/sealants work by reacting with the moisture in the air, no?

Edited by ship69
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9 hours ago, stevehnz said:

I can't answer those concerns but hopefully a milliput user will chip in & do so. I've doubts about needing gloves, people talk about using a wet finger to shape it & I guess remove excess, likewise I've read of it being used to fill wing root gaps & such like so it can obviously be shaped/rolled into long thin sausage shapes.

Steve.

Some folk find it can irritate or dry out the skin - I've not experienced that, but everyone's different. You can use a wet finger or a shaping tool to get it close to the right shape, and it's very effective. Far less sanding needed that way.

 

As for working it into tighter spaces, the secret is to get it warm first. Rolling the mixed putty between the palms of your hands will do the job, making it much more pliable.

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9 minutes ago, ship69 said:

Wait, I am no expert, but my understanding is that many 1-part adhesives/fillers/sealants work by reacting with the moisture in the air, no?

Polyurethane adhesives do, and cyanoacrylate cures by reacting with moisture. Polystyrene cement, tube or liquid, are solvents, and cure by outgassing - the more volatile the solvent, the quicker the curing time. Solvent-based putties are the same, and will shrink when they cure

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9 minutes ago, John Laidlaw said:

Polyurethane adhesives do, and cyanoacrylate cures by reacting with moisture. Polystyrene cement, tube or liquid, are solvents, and cure by outgassing - the more volatile the solvent, the quicker the curing time. Solvent-based putties are the same, and will shrink when they cure

OK interesting, however I'm not sure where that leaves me!

I need a filler/cement/glue/adhesive that:
- Has a low viscosity in order to get into the smaller gaps
- Does not shrink when it dries (in order to avoid multiple applications)
- Gives a good strong bond onto the styrene
- Has some flexibility (to stop it from cracking in use)
- Can be sanded easily

So any specific recommendations?

 

J

Edited by ship69
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5 hours ago, John Laidlaw said:

Some folk find it can irritate or dry out the skin - I've not experienced that, but everyone's different. You can use a wet finger or a shaping tool to get it close to the right shape, and it's very effective. Far less sanding needed that way.

 

As for working it into tighter spaces, the secret is to get it warm first. Rolling the mixed putty between the palms of your hands will do the job, making it much more pliable.

Thanks John, I guess there is no reason why the wet finger or warm palms couldn't be covered in disposable gloves that I read about folk on here buying thousands for peanuts. :D 

Steve.

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12 hours ago, stevehnz said:

Thanks John, I guess there is no reason why the wet finger or warm palms couldn't be covered in disposable gloves that I read about folk on here buying thousands for peanuts. :D 

Steve.

Yup - the disposable nitrile examination gloves are the ones to use, particularly if you have a latex allergy :)

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17 hours ago, ship69 said:

OK interesting, however I'm not sure where that leaves me!

I need a filler/cement/glue/adhesive that:
- Has a low viscosity in order to get into the smaller gaps
- Does not shrink when it dries (in order to avoid multiple applications)
- Gives a good strong bond onto the styrene
- Has some flexibility (to stop it from cracking in use)
- Can be sanded easily

So any specific recommendations?

 

J

This is unfortunately a Catch 22 situation - anything that bonds to the styrene will be solvent-based, and will therefore shrink as it cures. Also, putties tend to be fairly rigid when cured. On the plus side, they can be sanded easily, and are not affected by water if you're wet-sanding.

 

Car body filler can be very effective, especially when overcoated by something like Mr. Surfacer or Mr. Dissolved Putty. Multiple applications, yes, but they approach your other requirements better. Also, have a look at this thread for a more detailed look:
 

 

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On 2/5/2019 at 11:08 AM, bmwh548 said:

You get a bottle of cement (Tamiya, Gunze doesn't really matter), add small pieces of styrene inside (preferably styrene sheet, not old sprues), let it sit for a day or two and then you can use it as filler. The viscosity depends on how much styrene you put in. It's really good for filling gaps (thin layers though, you need to build it up) because after it's dry it has the same hardness as the surrounding plastic and it will react in the same way to sanding, rescribing, paint...

OK I have now been trying this. The results are rather mixed.

I don't like having to wait to apply endless layers, so I have been putting it on quite thick.

Yes it does of course shrink as the solvent/cement evapourates, but to compensate for this I have been applying it in extremely thick blobs.

 

One unexepected problem is that where I put a drop of solvent/cement onto the styrene, that has only a small amount of styrene dissolved in it, it actually burns a depression in the surface. i.e. When the solvent/cement dries out it must be leaving a layer of styrene that is more compact than the virgin styrene originally was.

To compensated for this effect, I have now been working with a much higher concentration of styrene in the solvent/cement. This of course makes the stuff quite goo-ey when you put it on.

 

The other problem with putting it on quite so thick is of course that it then takes rather a long time to evapourate. And whilst it is still soft it won't sand down properly.  So I have put my model onto a central heating radiator to help drive the solvent out. 

 

It looks like it will now take 24 hours to evapourate properly before I can sand it down. But from what I can see these "painted on" styrene are more or less just as hard as the original virgin styrene of my model.
 

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