What grit sandpapers set to use?

[arb65912]

What grit sandpapers set to use for sanding aircraft model before airbrushing the primer on?

There are some parts in my SU-27 1/32 Trumpeter kit that are glued, and I would like to sand them before airbrushing the primer.
I know I need to use different grits, which ones?

After putting the coat of primer, what grit do I use for light sanding it?


Thank you!

[AlanG]

All my sanding sticks are labelled Extra fine, Fine, Medium and Course. No idea what 'grade number' they are.

As for sanding before painting. I only ever do that if there is overspill from glue/putty or a scratch in the plastic. If i was going to do a NMF (Natural Metal Finish) then i might 'polish' the plastic before applying the primer but other then that i don't do any other sanding to my models, especially after painting. In fact i very rarely use primer

[Tim Marlow]

Agree with Alan. Only sand if you need to improve an imperfection. If you do need to remedy something, then depending on the issue I would go from 400 grit ( levelling bumps etc) to 800 grit used wet. You will certainly need to clean the surface afterwards to get dust and swarf off.
I always use primer though……unlike Alan

[arb65912]

Thanks, I see that there are different approaches to that subject, and it was expected. :smiling:

In my case I do have some glue marks and tiny scratches.
Tim Marlow so let's say I touch these with 400 and end up 800 wet, all cool but question again.
After primer, in the places where the scratches were, I need to sand again, very lightly, or no?
If yes, what grit?

[Tim Marlow]

Thanks, I see that there are different approaches to that subject, and it was expected. :smiling:

In my case I do have some glue marks and tiny scratches.
Tim Marlow so let's say I touch these with 400 and end up 800 wet, all cool but question again.
After primer, in the places where the scratches were, I need to sand again, very lightly, or no?
If yes, what grit?

To be honest Andrzej, it depends upon the final finish you want. If it is a matt camouflage finish, then probably not. If it is a gloss finish, like a metallic aircraft, then maybe……gloss finishes always show more flaws.
Primer can help here. It’s an even colour, so doesn’t artificially enhance a fault, and should go on smooth. Once you’ve primed the model anything that will show as a blemish in the final paint will show under the primer. At that point you decide if it needs correcting, or if you can live with it. If it needs correcting, minor filling perhaps, then the grade of paper you use simply depends on the degree of fault. The smaller the issue, the finer the grade of paper. For painted surfaces you shouldn’t need to go finer than 1200 though. Once you go past that you are into polishing…. After you have done the remedial work, just reprime the repaired area and you are ready to go.
Once you are happy with the primer coat, then just put on the top coat.….

[SUBSIM]

Thanks, Tim, that was helpful.

I watched a Flory video and it looked so practical, using these sanding sticks for cleaning up and blending filler and putty work on seams.

What he doesn't explain very well are,

• what's the difference between "sanding" and "sponge"?
• What are the various colors and grit level?

It appears black is course, blue is less course, green is fine and white is very fine for polishing. I've sent an email to Flory models looking for a printed overall guide sheet, there should be some listing of these sticks/sponges explaining this. I would love to get better at this and be able to make a seam disappear with as little effort as he does in the video.

I realize there are a lot of products like this that are available, these look good because of how clear it is what grit they are

https://www.amazon.com/gp/product/B09J18FN7G/ref=ox_sc_act_title_1?smid=A1VCFC48AFN8CL&psc=1

And these seem adequate as well, https://www.amazon.com/gp/product/B0...48AFN8CL&psc=1

I have some sanding paper but I have not had much luck using these well, I am learning how much pressure to use, what grit, etc. I also have some sticks, generic from a hobby shop, but they do not say what grit they are, I have to feel them and that's not entirely reliable

thanks!

[langy71]

If it helps, I purchased this from my local hobby store a few weeks back and I love it, works perfectly for me...(haven't tried them 'wet' yet, but I'm sure they'll be ok.)

http://www.meng-model.com/en/contents/59/308.html

There's also loads of different ones in the shop...

https://www.scalemodelshop.co.uk/accessories-c4/sanding-c138

I would suggest to start with maybe grabbing a multipack of various sizes. (maybe a pack from Albion Alloys)

[Tim Marlow]

“Sponge“ is usually a flexible grit on a sponge backing. A bit like a small bath sponge covered in sandpaper
If you have some sanding paper I suggest you make your own sanding sticks using ice cream lolly sticks. Just wrap some sanding paper around the stick and hold it in place with double sided tape or contact adhesive . You can write the grit number on the handle end. Just in case you aren’t sure, the larger the number, the finer the grit…
This sort of thing would work well, though I’m sure you could get them cheaper…you may even have some in the freezer

https://www.amazon.com/Wooden-Multi-Purpose-Popsicle-Sticks-Depressor/dp/B0931XXG2J/ref=sr_1_40?crid=KBMKMPWCW7ZZ&keywords=Ice%2Bcream%2Blolly%2Bstick&qid=1652979486&sprefix=ice%2Bcream%2Blolly%2Bstick%2Caps%2C166&sr=8-40&th=1

[Jim R]

One of the advantages is that your sanders can be any shape.

Very cheap as well. I have dozens, different grits and shapes.
Jim

[SUBSIM]

Beautiful, like I need another reason to buy ice cream! :tongue-out3:

Thanks! SO a sanding stick and a sponge are basically the same thing, cept with a sponge backing.

Is there a grit you find works best for polishing? 3200 ?

[scottie3158]

Although I don't do aircraft, one thing I use is a finger nail buffing block They have four sides from rough to very smooth they can be bought very cheaply from the local pound shop.

[rtfoe]

I'm surprised that sanding has become a niche process. I thought you just start with a coarse grit to get the rough surface into a somewhat even shape and then progressively go finer until it is as smooth as you want it too always running your finger over the surface and holding it against the light for a better angle of view. For better control is to have sand paper with a hard backing to prevent unevenness and oversanding. This can happen if you don't have a backing or use sponge sanding strips as the pressure excerted follows the contours of the surface just like a tank with a torsion bar suspension over rough terrain...if you get what I mean.
You can achieve good results in either wet or dry sanding although wet sanding will lead you to achieve a glass finish with polishing. Anything over 1200 grit feels like rubbing typewriting paper on the surface but it actually sands.
Seriously if you want to know how to sand, work on scrap plastic with different grits wet or dry until you're familiar with the process...quite therapeutic except for the dust and gunk.

Cheers,
Richard

[rtfoe]

Forgot to add...if you're into natural stuff, I've seen locals use sand paper leaves to buff wood carvings. The leaves can take a bit of your skin off if you accidentally brush against it while trekking....no joke.

Cheers,
Richard

[Airborne01]

On the rare occasions that I sand something I have a Micromesh polishing cloth set that goes from 3600 to 12000 grade (plus foam rubber polishing pad) - seems to work perfectly when needed!
Steve

[Tim Marlow]

I have stuff from 80 grit right up to polishing compounds, in sheet, block, sponge, and liquid compound. These have been collected over many years. It’s different horses for different courses. Some grades are better for some jobs, some for others. Broadly speaking, 80 grade is great for quickly flattening the bases on the little blokes….360 takes down big steps on kits very quickly….800 is a good general finish for anything that is matt varnished, up to about 3200 for gloss finishes or bare metal jobs, the rest are used on canopies and aircraft canopies. The polishing compounds are used between coats on cars and bikes and after final varnishing to get that great paintwork glow, and the really fine compounds polish up model car windscreens so they look like glass rather than plastic.