When to sand, and with what?

[Tomathee]

Seasons Greetings!

 

As the title really, I think I've missed a step or have a step to take still during priming and it's not turned out great. That alongside a couple of issues with previous models has lead me looking for a specific point by point guide but I haven't come across anywhere that has it in one place. So I thought I'd see what the folk of here go with and make a plan from that. Now I have a range of sanding sticks/sponges/sheets/needles etc of different grit, haven't yet chopped up an old tshirt or pair of jeans as some places suggest is included in the toolkit. I've put below roughly what I've done in my short modelling career as a starter so hopefully the gaps in my practice will show up once the replies start coming in from better knowledgeable people. I used a spray can primer on one model, which seemed to give a better finish than the brush painting which I do everything else in, so I know my technique needs improving and practice, just becoming a little frustrating to see the primer come out poor and knowing it will impact the final finish. One example of such is that I'm fairly certain I apply too much pressure, and with sanding a bit of sprue off it's easy to check progress, you can see it, sand it, run nail along to check periodically until it is smooth with the rest. However when it's just to prepare a layer of primer or paint ready for the next layer I have no real clue what I'm looking for, so more often than not end up taking off too much. Also, particularly with primer I'm never sure how 'good' a finish I should be looking for, as it's going to be covered over. So I've always ended up doing more than one coat, which I guess adds to the final amount of paint which is on a model and could make things worse if more is used than necessary. As a final point, are there instances where sanding shouldn't be done and whatever is being applied left as it is?

 

Removing from sprue - a stick or sponge, around 200 grit

Before priming - Don't sand (should I, for the primer to stick down better?)

Between primer coats - After not sanding resulted in a poor finish on a previous model I've now tried sanding with 1200 grit and water, then buffer/polisher (if there's a difference?) after reading some other threads and websites, however it's given a poor finish (can see marks from the paper) and taken it back to the plastic in places (acrylic primer, had at least 2 days to dry)

After primer, before paint - 1200 then 2000 grit and water

Between paint coats - 1200 grit then polisher

After last paint coat - as above

Then nothing after than once I start putting on varnish, decals etc.

 

So there it is, any help appreciated.

Edited December 15, 2016 by Tomathee

[S5 modeller]

Try washing the parts in warm soapy water before priming. That will help the primer adhere better. Mould release agent can be left on the kit parts when you get them, and needs cleaning off.

A gentle sanding of the parts before paint will help key the surface, and give something for the primer to grip onto. 

 

Brush painting is a bit of a dark art. Thinning the paint well, and using multiple thin coats will give a better finish than one thick coat.

 

Hope that helps you out.

 

Matt

[fewr9fkr9595]

200 is a bit coarse mate. May leave scratches and gouges behind that going to 1200 next won't remove. 

 

I use 400ish sanding sticks on sprue points. Then 600 & 800 paper on seams to clean up the mr surfacer 500 or 1200 i use as filler (applied with toothpick etc)

 

Then I use stynylrez which is quite a forgiving primer.  (Fills little scuffs etc) Some primers may need the surface smoother first eg 1200 paper. 

 

If after the first coat some seams need major work i may touch them in with mr surfacer again, then I leave them both to dry overnight, to allow it to be wet sanded again. 

 

If all looks good and only light work required, I flash off the stynylrez with a hairdrier and smooth it down with 4000 polishing cloth. Can build up several layers in half an hour like this. But dont apply too much pressure as the stynylrez can 'tear' cause its so fresh. 

 

Hope this helps. 

Edited January 5, 2017 by Tony Oliver

[Telboy1999]

Just a couple of tips from a not-very-experienced modeller.

 

Hope I'm not teaching my grandmother to suck eggs but If you're priming from a rattle can (as I do - I swear by Halfords grey auto primer) make sure it's well shaken before spraying. I'm talking 2 full minutes of vigorous shaking just to be sure.

 

Spray no closer than 20cm or 30cm - any closer and you'll put too much on.

 

Personally I don't sand primer unless the primer shows up a seam or area that needs more work. Once the seam or whatever is fixed, I'll put another quite light dusting of primer on the offending area.

 

As far as the finish you're going for is concerned, one of the main purposes of priming is to provide a single consistent surface for further painting, so give it a good eyeball and if it all looks smooth and even and the same colour all over after priming, you're probably there.