Quick question on cement

[kajnrig]

Hey all. Just a quick question, one I've asked others in the past but forgotten the answer to. Have any of you used gel-style plastic cement as filler? I'm talking for like the shallowest of gouges, just deep enough that sanding it away will cause more problems than it solves. I'm trying to repair an imperfection from using dull nippers and accidentally removing too much plastic from a kit. If so, how's your experience been? My small-area filler of choice (for like 2-3 years) was a bottle of plastic sprue dissolved in thin cement, but my bottle has since dried out and the slurry is so viscous as to be solid. I have two-part epoxy, but it's a whole half a table away and inside a cupboard door. And some tubes of Squadron green putty and Bondo glazing/spot putty, and autobody filler in the garage, but all of them are years old and probably no good anymore, and anyway, it's midnight here and I'm too lazy to use anything but the stuff immediately in front of me, which includes a bottle of thin cement, a tube of gel cement, and a kit I'm sanding the seam lines away on. Thanks.

[electric indigo]

I don't think the gel cement will harden enough to make a good transition. Do you have any superglue within reach?

[Big s]

If the gel cement is for styrene then you may have an issue in a day or so with shrinkage and you may have to refill the gap several times over the next couple days. If it's a ca or super glue then you will have far better luck. Ca filler can dry rather quick and can be sanded. There may be a need to do a second or even a third layer, but the fast dry time means you could be done filling and sanding and repeating in less than an hour.

[mickyg]

The gel stuff (and even some of the stuff in a bottle) often has acrylic compounds in it.  It's certainly work as a medium to "add" to the plastic.  But the problem is that it's also a pretty aggressive solvent.  So you would want to make sure you're using a very small amount.  Agreed with Big s on the possibility it might shrink too.

CA glues would be great except they often dry harder than the surrounding plastic, so you'd have to work really fast before it has completely set.  That or be very precise with your sanding.

Your original tactic of using melted sprue actually sounds like the best approach here.  Have you attempted making more with what's left and some new glue?  Might be worth trying.

[kajnrig]

Thanks for the tips, guys. I made a small "dot" of sprue slurry by mixing together some sprue shavings and the thin cement on a plate, then used that to fill in the hole (which was the smallest thing, just like if you took a needle and pushed it into the plastic). For that size, I thought MAYBE the gel would be okay, but I'm glad I decided not to use it. (I didn't know or forgot about the shrinkage issues, especially.)

No superglue, I'm afraid. Well, only an old gel bottle I used when I got the Tomy VF-31A months ago, but I haven't checked to see if it's still good (probably not) and it's a gel type, anyway, not the thin liquid variety.

Boy, it's way past due for me to clear/refresh my supplies.

[Kylwell]

I use Mr. Surfacer 500 for such shallow flaws.

[kajnrig]

You know, I've never used Mr. Surfacer. I'll be sure to check that out when I restock my supplies.

[electric indigo]

I'm a fan of Mr. Dissolved Putty. Works also on air bubbles in resin kits.

[David Hingtgen]

Is Mr Dissolved Putty similar to Mr Surfacer? 

[electric indigo]

It's thicker, so it has more filling power and doesn't shrink that much, but still thin enough to go into fine cracks.

[Big s]

I usually get a shrinkage issue with the mr surfacer, unless it's small scratch. I always find that I have to put a thick bit of mr sufacer and leave it there a couple of days to work.

[Kylwell]

Mr. Surfacer is best applied in thin coats. Thin layers dry faster which means you can follow up with a second (or third) coat w/o as much wait. Or, if you're like me, glob on a thicker coat before bed and let it cure overnight.

[big F]

What you can do is sand some spare plastic a sprue will do, then mix the dust into the glue it then works quite well, I've used it before to pack an area where it was difficult to get the filler in with out a load of effort to sand it back.

Edited June 29, 2017 by big F