Help! Fubar'd my latest project!

[Robert Porter]

While attempting join the Fuselage halves of my B-17G 1/48 Revell Model I totally overdid the putty on the seam. I will add pictures when I can. But the issue is sanding it off is not working very well. I have dropped all the way down to 240 Grit and tried both stick type sanders as well as just a sheet in my hand. Also have tried it wet and dry.

What seems to be happening is that I can remove the raised areas just fine and get back down to the surface, but all along the seam to either side of it is acting very resistant to sanding without also taking part of the skin near the joined area away.

I have looked at videos of sanding tutorials until I am dreaming about it but can't for the life of me figure out how to recover from this. Am I missing something simple? Or perhaps I am expecting too much in terms of time vs return on effort?

Any suggestions for particular methods or tools? I have fairly large fingers and a noticeable tremor in my hands, not apparent when sanding but it was very apparent when I was applying the putty.

I did mask each side of the join before applying the putty which did save me from just throwing the model out. I want to learn how to recover from mistakes like this because of course I can't just keep buying kits over and over. Something about that reminds me of the very definition of insanity.

 

[Crimea_River]

Try some acetone based nail polish remover like Cutex on the putty. Use a Q-Tip and dissolve the putty only. You can get some on the plastic but keep wiping it off as over time it will soften the plastic. Good luck.

filling without sanding

 

[Wurger]

First of all tell us what brand of a putty you've used. The acetone based nail polish remover can be ineffective with the kind of putty. What is more , the prolonged exposure of the polystyrene on the acetone can lead to its melting. As a result the model surface at the area can be damaged fully.

So..
1. post pics ..
2. what kind of putty..?
3 what sanding paper you used and the tool for the process... ?

 

[Robert Porter]

Full image should be attached. I used Squadron Putty, specifically their White Putty. Sanding paper is from 3M and is Wet/Dry sand paper and I have used grits as course as 200. No tool just my hand and fingers. I also used a series of sanding sticks from Tamiya in grits from 240 to 1000 I believe.

 

[Robert Porter]

Try some acetone based nail polish remover like Cutex on the putty. Use a Q-Tip and dissolve the putty only. You can get some on the plastic but keep wiping it off as over time it will soften the plastic. Good luck.

filling without sanding

Thanks for the link, very valuable info I appreciate it!

 

[Wurger]

Hummm .. the pic is too blurry but judging by what I can see in there It looks like not to be sanded at all. Or the sanding process was done incorrectly.

Did you wait enough long for ful hardening of the putty ?
Did you use some of water while sanding and keeping the sandpaper wet all that time?

 

[Robert Porter]

Hummm .. the pic is too blurry but judging by what I can see in there It looks like not to be sanded at all. Or the sanding process was done incorrectly.

Did you wait enough long for ful hardening of the putty ?
Did you use some of water while sanding and keeping the sandpaper wet all that time?

I waited about 20 hours for it to dry and mostly used wet sandpaper which I kept rewetting with my fingers from a bowl.

 

[Wurger]

20 hours might have been not enough. The Squadron putty has the warning it is flamable and harmful what suggests being thinned with a plastic melting thinner. If I'm are right, the 24h period isn't enough too. Two days or more would be OK IMHO. Then the sanding can be done.

To get rid of the effect we can see in the pic above you have to either sand down it again to the bare plastic at the area or apply some of the putty again and shape the fuselage top with sanding stick. Later the area has to be made smooth and polished if you want to paint it with silver coat. The colour doesn't "fogive" any imprefections. All scratches , colapsed areas , etc... will be seen.

 

[fubar57]

Wasn't aware the waiting time was that long for Squadron, Wojtek! I use this...

Spread in thin coats, it dries and can be sanded in an hour. So far, no shrinkage on any of my models and I've used this stuff for years. It also works well with Andy's (Crimea_River) "filling without sanding" link

 

[Wurger]

I use the Tamiya White putty and it works good for me and never sand it earlier than two days later.
As far as the Squadron one is concerned. It may dry quickly if applied with a thin layer but what about the plastic under that? It might be "softened" by the putty thinning agent. In the case the time for getting re-hardening can be longer. Sanding of a such soften area can result in the rough surface because of pressing , scratching while sanding etc...

"Pośpiech jest wskazany przy łapaniu pchieł" - nothing should be done in haste but gripping a flea.

 

[Wurger]

But back to the problem.. I'm convinced Robert did the sanding badly. Not all of the putty excess was sanded down I would say. Also I would say, the applying of the putty was done properly.

 

[Robert Porter]

But back to the problem.. I'm convinced Robert did the sanding badly. Not all of the putty excess was sanded down I would say. Also I would say, the applying of the putty was done properly.

That is indeed my worry, I know i applied too much as well over to large an area thanks to my shake. I have spent about two hours sanding and it still looks like I just started. I painted it just to see the errors more clearly.

Well I have ordered some sponge backed sanders so when they arrive I will go back at it!

 

[Robert Porter]

Wasn't aware the waiting time was that long for Squadron, Wojtek! I use this...

View attachment 357011

Spread in thin coats, it dries and can be sanded in an hour. So far, no shrinkage on any of my models and I've used this stuff for years. It also works well with Andy's (Crimea_River) "filling without sanding" link

I have some of that exact product, but it dries very fast and I found it hard to work with. Can it be thinned with something to make it take a little longer so I can work with it a bit more? My first tube dried out when I left the cap off for a half hour, its that fast!

 

[Robert Porter]

These are the sanding sticks I ordered, can't find them from a US based supplier but I know several folks that swear by them.

MEGA Pack Ultimate Modellers Sanders & Thinny Sticks

 

[mikewint]

For tough sanding use a Dremel at low speed with a fine sanding drum. There are holders for the tool and then you can use both hands for the model. The problem with anything hand operated is the natural arc you end up following as you saw back and forth.
I highly recommend post #2 and the "sanding" method in Crimea's post, it is SO much easier and works perfectly
I also highly recommend anything sold by FLEX-I-FILE. Check out flex-i-file.com

 

[Robert Porter]

I have a great Demel, but no stand yet, will look for one shortly I have seen them. Also thinking of getting a small bench grinder with a rag wheel, not just for models but lots of small polishing jobs that crop up around the house.Crimea's link looks like the way I will go next time. It honestly looked very straightforward and should be easier even with my shake.

 

[Wurger]

These sanding sticks look good.

As far as the applying of a putty is cocncerned... the main mistake made by almost all is the wrong understaniding of the idea of filling gaps. Mostly guys try to apply a putty at the top of a fuselage for instance doing that all around and along seams. While it should be done in the way the putty should be pushed into the gap. There is no need to apply it all around the gap edges. Therefore the gap area can be limited with a masking tape just to 1mm from both edges. For applying should be used a kind of a paddle or spatula. The diagram below can be useful for understanding. The general rule : the less of a putty on outside surface , the less of sanding.

 

[Wurger]

And a series of shots found via the net...

Applying ..

The wrong way ....

The proper way ...

 

[fubar57]

It does dry fast and I have left the lid of for at least an hour several times. I just take a flat tooth pick and remove the hard gunk. I've had this tube since 2007.

I use the technique described by Wojtek, used sparingly, smooshed in over small areas. Sometimes it takes 2-4 applications. As for thinning it, I've never felt the need but have read using lacquer thinner or nail polish remover

 

[Crimea_River]

Squadron putty should be sandable within the timeframe you allowed and 200 grit paper should cut into it easily. I can't figure out what you are doing wrong.