lesthegringo Posted April 22, 2012 Share Posted April 22, 2012 Guys, no matter what I do, I can't seem to avoid seam sinkage when joining the fuselage halves. I let the seams sit for a day before doing anything, then start by sanding to remove the worst of any discrepancy. I then use Mr Srfacer in thin thin layers, and let it sit for another day. I then sand, and if necessary repeat the Mr Surfacer, let it sit , and the sand and polish it all and it looks great. Then, after I paint it, it sinks in and leaves the same seam line that I was trying to avoid. What should I do? There are some metallic planes I want to do, but until I get the seam issue sorted, I refuse to touch them. Help!!! Les Quote Link to post Share on other sites
B-17 guy Posted April 22, 2012 Share Posted April 22, 2012 I'm not sure what you mean by seam sinkage, got pics of this? Quote Link to post Share on other sites
daywalker Posted April 22, 2012 Share Posted April 22, 2012 (edited) Can I ask what type of glue you are using? I used to experience the same problem when using Tamiya extra thin cement on seams, even tried waiting two weeks for it to evaporate then filled with CA glue and no joy. I switched to Tenax, and have not had a problem since. Edited April 22, 2012 by daywalker Quote Link to post Share on other sites
Bigasshammm Posted April 22, 2012 Share Posted April 22, 2012 Yeah It's clearly the culprit of whatever glue you're using. I'd say if you want to keep using the same glue then you'll just have to give it a good week to ten days or more to cure and then deal with any shrinkage after the fact with putty or filler or whathaveyou. I also use Tenax and love the stuff. Never tried Tamiya though so I can't comment on any similarities or anything. But I've always used Tenax and never had any seams that I noticed this on unless they were gigantic seams to begin with. As long as the dry-fit is nice and tight then you shouldn't have any issues with any shrinkage. If you're trying to use liguiq cement to fill in gaps then you will notice some when the seams pull away from each other a little. Quote Link to post Share on other sites
lesthegringo Posted April 22, 2012 Author Share Posted April 22, 2012 Thanks guys - looks like I'm in a hole then. I am in the UAE and there is only one shop that sells any kits, let alone being able to choose adhesives. I can't even get matt white or black! I have to rely on tubes of 'polystyrene cement' made by Humbrol and some laquer thinners if I want a liquid alternative. Cyano glue is available but sets too hard, and there is no outlet that sells epoxy based filler. Any help I can get to help me is very welcome B-17 Guy, seam sinkage is where you join two fuselage halves, then when you paint them the joint seems to have sunk down, even if you thought you'd sanded it smooth Les Quote Link to post Share on other sites
Thorsten Wieking Posted April 22, 2012 Share Posted April 22, 2012 I would try to avoid using Mr Surfacer at all. Dry-fitting, dry-fitting and dryfitting again, then glue the halves using not to much glue so that the used glue does soften and fuse the plastic yet has a chance to evaporate in a short time. There is a thread here in ARC about glue/plastic oozing out, drying and being used as a first step in filling any seam that might be there. Cheers Thorsten Quote Link to post Share on other sites
Skyraider Maniac Posted April 22, 2012 Share Posted April 22, 2012 What kind of paint are you using? It could be, also, that the paint and glue aren't getting along too well - I've had issues like that come up before. Quote Link to post Share on other sites
dmk0210 Posted April 23, 2012 Share Posted April 23, 2012 Put tape right on either side of the seam. Then build up your putty so it is at tape level, which will be a little proud of the surface when you remove the tape. Let it fully cure (at least overnight) before you sand it level. I like to use this technique with melted sprue (bits of sprue dissolved in Testors liquid cement). Quote Link to post Share on other sites
drhornii Posted April 23, 2012 Share Posted April 23, 2012 Use a piece of square sprue as a sanding block if I am following the seam issue correctly. The filler is softer than the plastic so it will sand down at a faster rate than the surrounding plastic. A flexi-file may also help. Quote Link to post Share on other sites
Netz Posted April 23, 2012 Share Posted April 23, 2012 I think your problem is that your making your own Liquid glue, which is commendable, but the lacquer thinner is the culprit ,it has a high rate of evaporation that is most likely the cause. Try the Tube Glue straight from the from the er ah tube, it will dry hard and will be sandable working as a filler. Also try to find a Trophy shop or a shop that fabricates Acrylic, they might be able to get you some Weld-On #3, or similar product that you can use. Curt Quote Link to post Share on other sites
lesthegringo Posted April 23, 2012 Author Share Posted April 23, 2012 (edited) Thanks for the suggestions, guys. I have to say, I'm very limited in what I can get here, so some of those options won't be open to me. I'm trying the cyano route, the big problem with it being how terribly hard it sets, so sanding it down is fraught. Is there any other filler available that doesn't set so hard but doesn't shrink? Car body filer (the two pack stuff) springs to mind, though I'm not sure I can get that either! The other issue I have is that it is impossible to see the imperfections until after the paint goes on. I try and put a coat of gloss over the areas I've filled,which shows up any imperfections very, but of course then you either have to wait until the paint fully dries, or you have to take the paint off. Is there a very rapid and hard drying gloss that I can use for this purpose? Edited April 23, 2012 by lesthegringo Quote Link to post Share on other sites
Mike C Posted April 23, 2012 Share Posted April 23, 2012 Can you get "sculptable putty" such as Milliput or Apoxie where you are? It's a 2-part epoxy putty. Try using that to fix seam lines. Might help... :unsure: Quote Link to post Share on other sites
lesthegringo Posted April 23, 2012 Author Share Posted April 23, 2012 that is a possibility - I'll have to check out Ace Hardware Thanks Quote Link to post Share on other sites
dmk0210 Posted April 23, 2012 Share Posted April 23, 2012 Try the Tube Glue straight from the from the er ah tube, it will dry hard and will be sandable working as a filler. When I was younger, I never had putty. I used Testors tube cement as a filler, as well as using it to glue the parts together. I would just wipe it on the seam with a toothpick or my finger, then sand it smooth. I actually still do have some of my earlier models and I can't see any seam lines under the paint, so it worked and didn't shrink. Quote Link to post Share on other sites
JesniF-16 Posted April 24, 2012 Share Posted April 24, 2012 (edited) The other issue I have is that it is impossible to see the imperfections until after the paint goes on. I try and put a coat of gloss over the areas I've filled,which shows up any imperfections very, but of course then you either have to wait until the paint fully dries, or you have to take the paint off. Is there a very rapid and hard drying gloss that I can use for this purpose? I find the use of acrylic silver paint (I use humbrol) to be quite handy and simple. Simply paint brush it on the seam and the imperfections will show through. The acrylic paint dries quickly and easily wipes off with 91% alcohol. Although the true test is putting on a very light first coat then fixing the rest of the imperfections... /Jesse Edited April 24, 2012 by JesniF-16 Quote Link to post Share on other sites
lesthegringo Posted April 24, 2012 Author Share Posted April 24, 2012 Thanks, will try the acrylic silver trick! I have some Tamiya acrylic, hopefully that will do the trick Quote Link to post Share on other sites
The Loggie Posted April 24, 2012 Share Posted April 24, 2012 G'Day Les. There IS another solution for you. Go to a plumber/hardware shop and buy some plumbers goo. It is just MEK. And while it stinks, it is an excellent glue for plastic. Others may vote against using MEK BECAUSE it requires careful usage (and because it stinks). Good luck. George, out................. Quote Link to post Share on other sites
Richard M Posted April 24, 2012 Share Posted April 24, 2012 You can try mixing some baby powder into the cyano, prevents it getting too hard to sand. Using cyano avoids the shrinkage problems as it does not melt or soften the plastic. http://s3.zetaboards.com/locate_and_cement/topic/744332/1/#new Quote Link to post Share on other sites
Thorsten Wieking Posted April 24, 2012 Share Posted April 24, 2012 Although I do not use it and think that it is not the best solution - some people use liquid correction fluid (e.g. for typwriter written documents etc.) to fill small imperfections. Sometimes white glue / wood glue could be an option, but again not the best solution. Are there any stores that stock Games Workshop products? If so, check their "liquid green stuff". Cheers Thorsten Quote Link to post Share on other sites
lesthegringo Posted April 24, 2012 Author Share Posted April 24, 2012 I work in the aircraft industry - MEK is easy to get, same as trich is ( although not as easy as it used to be) I'll give those a go, in the meantime I've persevered with the CA as a filler, and have realised that as long as I work with it quickly, it can be sanded more easily than I thought Thanks to everyone who helps here! Quote Link to post Share on other sites
dmk0210 Posted April 25, 2012 Share Posted April 25, 2012 (edited) The only thing I don't like about CA is if you don't get it perfectly right immediately, it is very hard to sand down or scribe later. Though adding talc or micro balloons to the surface first helps solve that problem. Edited April 25, 2012 by dmk0210 Quote Link to post Share on other sites
lesthegringo Posted May 10, 2012 Author Share Posted May 10, 2012 You can try mixing some baby powder into the cyano, prevents it getting too hard to sand. Using cyano avoids the shrinkage problems as it does not melt or soften the plastic. http://s3.zetaboards.com/locate_and_cement/topic/744332/1/#new Used this method, and with a bit more savvy on the use of Cyanoacrylate has revolutionised my modeling, thanks very much for all the help! I'm even tackling ejector pin marks in places I would not have done before1 Another satisfied customer! Quote Link to post Share on other sites
Hawk10 Posted May 10, 2012 Share Posted May 10, 2012 (edited) Check your local (or regional) Yellow Pages for a commercial plastics shop (Cadillac Plastic for example). They should be able to furnish styrene liquid cement - That's where I get my Weld-0n #3 - only problem I have locally is I have to buy it in gallons - your local dealer may be able to supply it in pints and quarts. Edited May 10, 2012 by Hawk10 Quote Link to post Share on other sites
DutyCat Posted May 11, 2012 Share Posted May 11, 2012 You are priming, right? Quote Link to post Share on other sites
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