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Hi all,

I’m trying to spend more time finishing my models before painting them. So assembling, forensic removal of mould lines and filling gaps. When filling and removing mould lines from large flat or curved (but smooth areas) like shoulder pads I find sanding works better than a knife. There was a sanding pad in a modelling set I bought and it has 4 grits on it and the finest one worked best but I have no idea what grit it is.

Can anyone suggest what grit I should be working with to get a nice finish pre primer?

Thanks

You don't want anything too rough. At least 120 grit, I reckon somewhere between that and 400 would be ok. Plastic is fairly soft and won't take much sanding.

I must say I find the opposite. I much prefer to scrape off mold lines with a scalpel or hobby blade.

I would arm yourself with the following

1) A good scalpel (buy spare blades). What I find is that scalpel blades are just a touch too sharp when fresh, they take a little use to dull down to an ideal edge for plastics. Sometimes doing a few metal models or rough things like bases is a good way to work in a new blade.

2) Some rubbers, normal hard rubbers/erasers. Don't get the putty kind, get the standard firm ones. These will be important in just a moment

3) A half round (if you only get one) small 900 grit diamond file. If you want to file use this, it will last longer then emery boards and such and its the best grit for soft materials.

Downside is plastics are soft so they will clog the file up fast; that's what the rubber is for. You run the file over the rubber and it cleans out all the gunk.

I only know of one place selling the diamond files - https://www.eternaltools.com/small-diamond-files

I've got a set of old tiny metal files. They work well but you need to be careful not to overdo it.

When I need sanding paper, which is rare, I use the one you use for cars, it is not aggressive at all.

For rougher needs, like big chunks of plastic or when you actually want to reshape something via sanding, you'd be surprise how well a silly nail file serves. Once again not for precision working.

use the right tools for the job, get yourself a set of jewelry files, any set will do.

I use AK Interactive sanding sticks, they are great although more expensive than just using regular sanding paper.

I typically cut off the pieces from a sprue loosely with nippers, leaving plenty of gate on the part. Then I either saw the gate nub off with my JLC razor saw, or use a dullish hobby blade and gradually carve the nub until it is very small. To finish things, I take out the sanding sticks, usually starting with the medium sanding stick (240 grit) used in wet sanding mode. Then I finish up with the fine sanding stick (600 grit) in dry sanding mode. The 240 grit sanding in dry mode might be a bit more effective, but I find it creates unsightly "rash" unless used wet, so I almost never use it dry.

To inspect the end result, I might go ultrafine stick (3000 grit) and polish the area to a glossy shine, the reflections of the shine reveal any possible anomalies in the shape.. which, if found, I then return to using the coarser sticks.

IME the 240 grit medium stick, used in wet sanding mode, is ideal when you need to remove excess plastic from GW styrene. Using the finer grits will also whittle down plastic some, but might leave bumps (ie they are too fine so they will only smooth the edges of a clump, instead of removing it)

All YMMV as usual.. I also have needle files but probably have rubbish ones, as I much prefer my sanding sticks over them

Yep, jewellery files. They come in all sorts of shapes in the pack, so do detail well.

But, I got a Dremel multi-tool for mold lines on scenery. That stuff is huge, and the files lose their grit in no time on them.

Good suggestions here regarding grit. Very fine is best. 400 or more.

I agree with the sentiment of having several different type of tools. I use sandpaper, files and scraping with a knife depending on the material. I often use emery boards from the dollar tree too. Cheap and just the right size.

Two additional ideas.
Maybe get a piece of very fine emery cloth. It's a cloth version of sandpaper. Very flexible sturdy and doesn't crease the same way as sandpaper. I've been using the same piece for years.

Lastly, for things you want to be flat, a piece of fine paper on a clipboard is always close at hand for me. Much more useful when you want a flat surface than a sanding block or hand holding the paper.

 Skinnereal wrote:
Yep, jewellery files. They come in all sorts of shapes in the pack, so do detail well.

But, I got a Dremel multi-tool for mold lines on scenery. That stuff is huge, and the files lose their grit in no time on them.

Hi I have a rotary tool but I have no idea which bit to use for fine sanding

I use this one for lines and lumps on terrain, and finish the details with a file:

https://www.dremel.com/za/en/p/sanding-band-mandrel-13-mm-grit-60-2615040732

As an additional suggestion, try finishing off sanded areas with a quick application of Tamiya Extra Thin liquid cement. It helps to remove the very fine scoring that sandpaper can leave on the surface of the plastic.

 Snord wrote:
As an additional suggestion, try finishing off sanded areas with a quick application of Tamiya Extra Thin liquid cement. It helps to remove the very fine scoring that sandpaper can leave on the surface of the plastic.

Such scoring is that same "rash" I talked about in my posts. Besides using thin plastic cement for smoothing it out (recommend Mr Hobby SP cement, its the best thin cement on the market AFAIK), you can either smooth it down with finer grit sanding (600 grit and above), or better yet, use wet sanding which prevents such scoring in the first place.

 tauist wrote:

 Snord wrote:
As an additional suggestion, try finishing off sanded areas with a quick application of Tamiya Extra Thin liquid cement. It helps to remove the very fine scoring that sandpaper can leave on the surface of the plastic.

Such scoring is that same "rash" I talked about in my posts. Besides using thin plastic cement for smoothing it out (recommend Mr Hobby SP cement, its the best thin cement on the market AFAIK), you can either smooth it down with finer grit sanding (600 grit and above), or better yet, use wet sanding which prevents such scoring in the first place.

So wet sanding is just putting water on the sand paper?

mrFickle wrote:

 tauist wrote:

 Snord wrote:
As an additional suggestion, try finishing off sanded areas with a quick application of Tamiya Extra Thin liquid cement. It helps to remove the very fine scoring that sandpaper can leave on the surface of the plastic.

Such scoring is that same "rash" I talked about in my posts. Besides using thin plastic cement for smoothing it out (recommend Mr Hobby SP cement, its the best thin cement on the market AFAIK), you can either smooth it down with finer grit sanding (600 grit and above), or better yet, use wet sanding which prevents such scoring in the first place.

So wet sanding is just putting water on the sand paper?

Yup,, I usually use a brush and water, and brush the water onto the part to be sanded.. you dont need to soak it, just enough to moisten the surface. In a pinch I even use my saliva, but thats just cuz I'm gross like that hehehe!

Not sure if the sandpaper will wear out faster when used in wet sanding, but at least the dust will not cake the grits

Have you tried the backside of an exacto?

I’ve been using the modelling knife, the diamond file and polishing pad. The diamond file has made the biggest difference to add into smoothing down the plastic