What is the trick with plastic putty

[A_S]

Hi all

 

how do you all deal with filling very fine gaps? 
 

ive watched many tutorials on YouTube where people seem to fill gaps and wipe any excess away very quickly with a cotton bud but whatever I seem to do it takes me hours and hours of filling, sanding, filling again, cleaning up lots of mess, painting, finding the gap isn’t filled, filling again. praying that when I put the main coat on any gaps disappear...

 

if I do the recommended technique above I find that the putty generally comes out of the gaps at the same time (they are very fine) and if I leave it too long it drys hard and takes too much effort to clear with with Cotton bud. Ie requires a lot of force and or water and still takes the putty out the gap.

 

ive resorted to just pilling it on top of the gaps and pressing in and then spending hours (literally 8 to 9 hours of work on 4 or 5 gaps) filing it back smooth. Even then the gaps still appear after painting.

 

im a bit stuck as to the best technique - I just know it’s wasting my time at the moment!
 

 

[Tentacles]

I used to really struggle with this (not that I'm any expert now). 

Things that have helped me:

- mask around the area you're puttying

- immediately wipe off excess with a cotton bud dipped in acetone, or water (depending on the type of putty you're using) 

- go gently, and be prepared to work the same area more than once. Putty can shrink. And even thin gaps can be deep.

- prime or undercoat before paint. At this stage you might find the filled area needs more work. (That's one of the main reasons for doing this). Again, you may have to do this more than once, to make the filler less visible.

- this is your free time and it's supposed to be enjoyable; "good enough" is preferable to perfection

 

[Filler]

I echo everything @Tentacles has said, but I’d like to add one suggestion. For typical joints like those of fuselage halves I now use sprue-glue a lot of the time. As it’s just melted polystyrene it’s the same material as the rest of the kit and it doesn’t shrink, crack or split. So I’ve found less repeat applications are necessary in my experience. So if you’ve an older bottle of Tamiya extra thin or similar, then add some chopped up bits of sprue to it and after a couple of days you’re good to go. I should add that some work on the consistency is usually needed.

[Troy Smith]

5 hours ago, A_S said:

how do you all deal with filling very fine gaps?

stretched sprue  or plastic strip/sheet. 

slow method, use standard glue, or fast, superglue, 

for a fine even gap, plastic sheet or strip is great with SG.

 

Or, superglue, or superglue and talc.   unbeatable for sheer speed.   the SG/talc mix is quite soft, SG in it's own when hard is harder than plastic.  Work as soon as 'hard', do not leave it.  

I just use cheap SG from the pound shop,  mix on jar lids, mix and apply with a small flay screwdriver, you can scrape the mix off the screwdriver after.

 

Finally.  Avoid gaps. 

 

from your tales of hours of work trying to fix a problem,   I say this as i have some putty monster from my youth that I have looked at as an adult and remembered the problems and now realise that much of the above would have saved me a lot of work and made a far neater job as well.

 

So spend time getting a better fit, test fit, adjust by sanding and scraping, or if needed, shimming.   Make sure alignment pins do actually align. remove or adjust if not.

 

make sure mating surfaces are true and flat.   

 

I often assemble with SG as well.  Or, use tiny drops of SG to tack, if the fit is poor, you can crack apart, remove the tiny dots and work on fit.

If fit is good, you can use the capillary action of thin liquid glue to strengthen those joins.

 

On new kits, fit is often VERY tight and with fine tolerances, and a missed mould line, sprue nib or coat of paint on a interior bulkhead can cause misalignment and thus gaps.  Just because it all fitted before you painted the interior  it does not mean it will fit after(new Airfix and Eduard are examples of these)

 

Adjust construction sequence, If needed. you can sometimes join upper wings to a fuselage first, and then add the lower  wing (eg Spitfire, Mustang, kits with a one piece lower wing) 

 

Sometimes there just are gaps though.

 

HTH

[dogsbody]

As I am far from experienced at this issue, all I have is my Airfix 1/72 Hurricane. For this, I used Mr Surfacer 1000 applied with a cut-off sewing needle eye, that I had previously used for superglue application. When dry, I lightly sanded the Mr Surfacer with some 600 grit sandpaper. This was followed by a Tamiya Medium, then a Fine sanding stick. 

 

 

 

 

 

 

It seems to have worked good so far.

 

 

 

 

Chris

[dnl42]

3 hours ago, Troy Smith said:

Finally.  Avoid gaps. 

 

from your tales of hours of work trying to fix a problem,   I say this as i have some putty monster from my youth that I have looked at as an adult and remembered the problems and now realise that much of the above would have saved me a lot of work and made a far neater job as well.

 

So spend time getting a better fit, test fit, adjust by sanding and scraping, or if needed, shimming.   Make sure alignment pins do actually align. remove or adjust if not.

 

make sure mating surfaces are true and flat.   

Seriously, do this!

[Pete in Lincs]

Go to Home Bargains. In the stationery section find the typists correction fluid. 

You can run this into fine gaps. Let it dry off a bit and wipe excess away with IPA or use fine micromesh and spit.

 Repeat as necessary.

[A_S]

Thanks for the tips - I may try with superglue and just sand in future - what benefit does adding the talc have? On my current one I made sure i applied too much glue and did use superglue hence the lack of filling on the top as I've just filed the superglue flush with the plastic

 

The problem is - the fit is pretty poor on these parts the gap if butted up against 1 end is near half a mm i'd say and the working area is not very easy to access, I've made 3 of these now and every time i was hoping my experience would lead to a better process but sadly it hasn't!

 

 

I've done this about 4 lots of applications but its still not flat. I'll do as suggested now and prime then fill again and sand -> I just wish i could avoid this step

 

 

[Troy Smith]

18 minutes ago, A_S said:

what benefit does adding the talc have?

bulking agent.  Greatly  increase the filling capacity, and the mix is softer than plain SG, so easier to work.

 

20 minutes ago, A_S said:

The problem is - the fit is pretty poor on these parts the gap if butted up against 1 end is near half a mm i'd say and the working area is not very easy to access,

OK, are you trying to fill parts added to the lower bumper with what looks like white filler lines?

 

This is a candidate for shimming with plastic strip/sheet, as it a thin even gap

 

shim part until level, or maybe a little proud.

 

use sheet to fill gaps, leave some sticking out, let set, and then trim with a knife. 

 

If they are insert parts that don't fit well, you can add sheet to an edge to fill the gaps, check fit, take out, and then trim sheet attached to insert part, making the trimming easier, then fit the inserts.

 

Aim to minimise gaps and steps, this then minimises filling and sanding, DO NOT just stick in and then try to make good.  

 

If you do not have model specific plastic sheet, check for packaging, lots of thin grades of sheet for free.  If using superglue, then dissimilar materials are not a problem, as long as they stay stuck, but plenty of polystyrene is used.

 

I don't if you do any scratch building,  if you do, or plan too, but don't have any styrene sheet,  get an assorted pack of  Slaters Microstrip 1001 

(if you google it you will get various hits or you may have a shop that has it, eg Parabellum?)

 

This is the only one of a mix if widths and thicknesses.  It's really useful.   It cost about £5, but you cannot make thin strips easily.  (it curls when you cut it) 

Alternately just get sheets of 5 thou (harder to get) 10 thou, 15 thou and 20 thou plastic card.   Thicker grades are useful, but in this case you can just laminate  them

10 thou =~ .25mm

20 thou =~ .05 mm

40 thou =~ 1mm

 

HTH

[A_S]

I've built a couple of brass loco's and so I'm well aware of slaters stuff as its a railway based shop! I have a few bits of plasticard hanging about but wouldn't it be difficult to shape round the contours? especially the bottom which has a lip, you cant really see it in the photo.

 

Trying to visualise what you mean - i.e use plasticard to fill the gap, glue it, sand it? seems like a great idea if it were a more flat surface with less contours - I'd say it would be a lot more effort on these bits?

[Troy Smith]

28 minutes ago, A_S said:

I have a few bits of plasticard hanging about but wouldn't it be difficult to shape round the contours?

stick in a strip, deep enough to  leave it sticking out  further than the contours,  let it set,  trim with a sharp knife,  once you start a trim, you can press side of the blade against the existing contours and use that to guide the blade,  thin card cuts very easily.  Done carefully you should have a minimum of clean up.

You add multiple small bits, and 10 thou curves very easily.  

I don't know if that explains it well enough? 

 

in the pic,  since I don't know what the bumper insert look like before, I assume that they are the bits with the white filler lines round them? 

 

I'd have been looking at finding card that will fill the gaps, rather than filler and the add it to the insert parts, let it set,  trim closely, then add part to car, and then do a careful final trim when set. 

 

If the fit is sloppy,  for example, the right insert look to be sitting to far in, which is what I mean about adding thin shim, to make it level with the surrounding surfaces,  you migh need to aim toi make the insert as level with the surrounding, and then fill the gaps.

 

Note, for finishing fine surface jobs, Mr Surfacer is really good.  

 

Perhaps experiment with filling techniques on a scrap kit,  make a cut into one with a saw, and they experiment with plastic strip vs superglue and talc, 

Or try Milliput.

It's a bit of chore to mix, but can be smoothed off with water,  and does not shrink or crack.    

 

The key is for you to do this, that is experiment,  if I was able to examine the kit and the problem in detail,  I could perhaps give a better answer.  

 

On 27/06/2020 at 16:23, A_S said:

ive resorted to just pilling it on top of the gaps and pressing in and then spending hours (literally 8 to 9 hours of work on 4 or 5 gaps) filing it back smooth. Even then the gaps still appear after painting.

 

Mr Surfacer is good to this.  

 

If this taking hours, then the time taken on some experiments in different filling methods, as long as it gets to a method that works for you, will save you time in later, as you can deal with filling problems fast quicker.

 

HTH?