Would anyone be kind enough to give tips for using acrylic paints?

[Jon-1296662]

As someone who has not made or painted a model for nearly fifty years, and who has had a bad experience with using acrylic paints a couple of months ago, I would really appreciate anyone who would be willing to share their experience and knowledge about the best way to use acrylic paints on these models, and especially, on how to make the paint adhere to the plastic firmly. And I would especially like to know, if it’s possible to use enamel and acrylic on the same model, or do I need to wait until I have the correct shades in one media?

 With thanks in advance.

[SteveM6]

I always use a primer on models for two reasons. Firstly it gives a key for the topcoat to adhere to and secondly it acts as a seal over what is below. The primer may still react with existing paint or printing but at this stage it is easier to sand it back with very fine wet and dry abrasive used wet.

It is possible to use enamels and acrylics on the same model but there is always a risk that they won't play nicely together so it's best to test on something else first.

[Tour de Airfix]

Jon, as Acrylics are water based the most important lesson when painting on plastic, as our kits are, is to wash your kit first in detergent. This removed the residual oils from the surface that are left as part of the moulding process. The, from my experience, it depends is you are using a paint brush or air brush. My personal advice for starters would be:

Paint Brush:

1. Make sure the consistency of your paint is like that of single cream - not too thin, and not too thick. Use water or the paint company's thinner to thin if too thick.
2. Paint at least 3 very thin coats, letting each dry to touch before applying he next. The first will look awful, the second marginally better and by the third you should get a good coverage. Paint colours differ, so you may get away with less coats or with some may even need more. Be patient. 
3. Leave your model 24 hours for the paint to cure before handling it, as you'll find it will easily scratch off even if dry to touch.

Air Brush:

1. Make sure the consistency of your paint is like that of milk - it needs to be thinner than brush painting. Use water or the paint company's thinner to thin if too thick.
2. Apply a coat of primer before top coat. Not all recommend this, but I find the top coat adheres better and it means I need less of it. 
3. Leave your model 24 hours for the paint to cure before handling it, as you'll find it will easily scratch off even if dry to touch.

[peebeep]

2 hours ago, Tour de Airfix said:

Jon, as Acrylics are water based

Can we dispel this old chestnut please? Some acrylic media is, indeed, water based (aqueous), but not all acrylic media is water based. Acrylic media can be spirit based and miscible with water, such as regular Tamiya and Mr Hobby. Others can be lacquer based such as Mr Color and Tamiya LP. I've never seen it in the context of our hobby (as far as I'm aware), but polyurethane acrylic is yet another possibility. The most commonly available brands of aqueous acrylic I can think of are Humbrol, Revell and Vallejo. There's any number of different media available from the likes of MIG, AK, MRP, SMS etc. 

Going back to the original question, as mentioned above if you want aqueous paint to stick with good adhesion, then a primer is pretty much de rigueur. 

[Tour de Airfix]

6 hours ago, peebeep said:

Can we dispel this old chestnut please?

Good point, my apologies. I’ve never used any non-water based acrylics and nor would I ever want to. I would imagine the majority of us wouldn’t go looking for them either, but it’s a very valid correction to make 👍

It was my error in replying as I at first just typed “use the manufacturer’s supplied thinner” but then thinking of Humbrol/Airfix’s paints, and as we’re mainly focussed here on Airfix, I modified my response to include “water” in that we don’t have an Airfix thinner and was concerned that would have opened a whole new can of worms to someone new to acrylics 😉

[Tour de Airfix]

7 hours ago, peebeep said:

then a primer is pretty much de rigueur

I have personally never tried priming a whole kit first with a hairy stick/brush. I normally got away, in the dim and distant past and before I started using an airbrush, with giving the parts a good wash. Having found the primer to be generally thicker had always worried about losing some of the detail in the kit. Thinking about it, this would probably negate my approach of multiple very thin layers of paint. That said, one could always use a rattle can of primer paint. With care, this would quickly lay down a good adhesive surface for a nice bit of brush painting … just shows, there are many ways to skin this cat 😉

[peebeep]

13 hours ago, Tour de Airfix said:

 … just shows, there are many ways to skin this cat 😉

QFT. In respect of thinning aqueous acrylic in the absence of own brand thinner, there is some benefit in using distilled water (battery/iron top up) rather than tap water. If you want to slow the drying time you can use a small drop of dilute glycerol. I sometimes use the paint supplied in gift/starter sets on a waste not want not basis and found that thinning with a small amount of old formula Klear worked wonders in terms of coverage and adhesion, especially for bristle brushing. If you can find it, Pledge Revive It floor wax is a Klear substitute. I'd have to say I have no idea how any of these products might be compatible with the new airbrush ready Humbrol acrylic paint. 

[paul71]

i brush paint and I've never primed a model yet but i do wash the sprues in warm soapy water just a little bit of washing up liquid and then rinse under a hot running tap dab excess water off and leave to air dry for around a day.

I've used both acrylic and enamel on the same kit from humbrol, revell and vallejo  not had a problem yet but i have heard that some people have had problems but if you don't try new and different things you don't know how it will go for you.

As for using acrylic paints I've found them a lot better to use than enamel so always go to my acrylic colours first if i have the colour in both types i always give the pot a good stir or shake the bottle really well before using, when painting i have a small tub of water so i can keep cleaning the brush as i paint so i don't get any small dry bits off the brush when doing big areas and just dab off the excess water on a bit of toilet paper.

if I'm going to mask over the paint to get some straight lines between different colours i will always leave the paint to dry at least 24hrs before i put any masking tape on the kit but I'm a slow builder so this suits me.

i would say always try different things and see what works for you and keep practicing. 

[Jon-1296662]

On 24/04/2024 at 20:47, SteveM6 said:

I always use a primer on models for two reasons. Firstly it gives a key for the topcoat to adhere to and secondly it acts as a seal over what is below. The primer may still react with existing paint or printing but at this stage it is easier to sand it back with very fine wet and dry abrasive used wet.

It is possible to use enamels and acrylics on the same model but there is always a risk that they won't play nicely together so it's best to test on something else first.

Firstly, would you tell me what product you use for a primer?

Secondly, have you ever tried keying the plastic, with something like a one thousand or an even finer grit polishing paper, or is there a reason why this won’t work(I know that a coarse grit especially with a hard backing paper/wet&dry, would destroy the fine details), but I do have some very fine polishing papers & some fairly soft foam pads, the first of which are very soft and the foam pads are fairly soft, for polishing silver to a very high shine, which may knock back and key the plastic. And I know I would have to wash the whole thing again, to ensure I’d removed any possible loose particles, so that the paint didn’t clump up, so do you think it is worth trying a gentle keying, or do you know that it won’t work(I don't want to risk ruining a model, unless there’s a real chance of success, especially if there’s a tried and tested method that can be used)?

Lastly, does acrylic paint need to be fixed/varnished over to make it safe to handle, once the last coat has fully dried off, and if so, can you please suggest which product you have the best results with?

     With thanks in advance,

           Jon

[SteveM6]

@Jon-1296662 I use Halfords primer - pick the primer to suit the top coat. Grey is the most used but use white under yellow and red under red/maroon. Light coats or you will swamp the detail.

Any sanding is done with P500 or finer wet and dry abrasive sheets used wet to stop scratching and clogging. I find that using a good primer negates the need to key the plastic but if necessary the same method of wet P500 can be used.

Practice on an old or scrap body first.

[Ratch]

Jon, have a read of some of the build reviews, there are lots of tips to pick up.

[paul71]

1 hour ago, Jon-1296662 said:

Lastly, does acrylic paint need to be fixed/varnished over to make it safe to handle, once the last coat has fully dried off, and if so, can you please suggest which product you have the best results with

A varnish will help protect once painted i would leave at least a day for the paint to cure, a gloss varnish is best for putting decals on it helps the film around the decal blend in see at the top of the main pages about putting decals on, then you can put a coat of varnish over it to get the finish you want gloss, matt or satin.

at the moment i use humbrol clear found it to be good I've still not been able to find the floor polish that some people use (other people will be able to help point you in that direction), A few light coats of humdrol clear is better than one thick coat as its self levelling so it can pool in places if it goes on too thick, a problem I've had in very hot humid weather is that it can dry blotchy and white so i leave the varnish off till the temperatures have cooled down if it has happened usually another coat of varnish has sorted most of it out.

Edited April 27 by paul71