Is it safe to paint humbrol / revel enamel paint over car spray paint?

[Simon Robinson 4Participant @simonrobinson4]

I don’t have an airbrush for my model so I’m thinking of using silver ‘alloy-wheel’ spray paint over the model ( it’s wood and already primed with water based acrylic primer) but I want to add some detail over it using humbrol enamel paint. It’s difficult detail so masking isn’t practical.

The spray paint is solvent based containing Xylene, could there be any chemical reaction between the spray paint and enamel paint that could dull or spoil the finish even if I wait till spray paint is fully cured? I want a shiny natural metal finish. Also will water slide decals be ok on the spray painted sections?

Edited By Simon Robinson 4 on 15/08/2023 12:18:28

[Simon Robinson 4Participant @simonrobinson4]

[BizibilderParticipant @bizibilder]

Why not paint a test piece? It doesn't have to be very big but you must match the paint and painting/drying sequence that you intend to use. That way you can be sure of the results.

[BazParticipant @baz89810]

As Bizbilder says paint a test piece, nobody on here will be able to tell you with any certainty if the paints will react, it’s something you have to find out yourself for your particular application.

[HOWARDTParticipant @howardt]

I would as others say do a test before committing. Do the test with different hardening times of the base paint. With enough curing time most paints will be sufficiently hard to not react with most other paints, it is the amount of time the solvent lays on the sub surface resulting in softening. I tend to prime my steel parts as soon as they are finished to prevent rusting then it may be months before any subsequent paint is added, which means nothing other than abrasives will remove it.

[Nick Clarke 3Participant @nickclarke3]

When I mixed, matched and sold car paint many years ago the mantra was that you could overcoat cellulose with a synthetic enamel paint but not the other way round.

Assuming your xylene behaves like cellulose and I suspect it will, you can almost certainly put synthetic enamel on the solvent based paint – but it not unwise to try a test first.

The mnemonic was you put (S)alt on (C)hips but not (C)hips on (S)alt

(C) = cellulose or other solvent based paint and (S)=synthetic enamel

But if you want an extra level of safety have a look round your local model shop for alternative paint ranges to Humbrol as some (Tamiya and Revel spring to mind but check) are water based acrylic.

Edited By Nick Clarke 3 on 16/08/2023 10:29:34

[Ramon WilsonParticipant @ramonwilson3]

You will have no issue applying Humbrol or most enamel paint over 'cellulose' based' surfaces but as others have said not the other way around. Let the cellulose surface 'gas off' for a day or so though before applying though to prevent any reaction.

Humbrol paint, I'm afraid to say though, is not the paint it used to be. Probably down to legislation but it's make up is not the same and it does not perform like it used to. Not much of an alternative out there in small volumes except Hannants Extra Colour Enamel

The (modelling) acrylic paints of which there are a vast amount to choose from will often crack if put over cellulose surfaces – bit like a Chinese vase – but the AK Real Colour acrylics (in the glass jars) are lacquer based so may prove ideal. Tamiya also do a lacquer based range now as well.

As a basic guide where the model acrylic paint is concerned there are fundamentally two types – polyurethane based, usually presented in small polythene bottles and the lacquer based which normally come in glass jars or bottles.

Incidentally when I bought my first tinlet of red enamel paint from the 'Humber Oil Company' (pre Humbrol) it was 9d – nine old pence. I think the cost for the same size 13ml tinlet is now around £2.50

Hope that helps some – Tug

[Mark RandParticipant @markrand96270]

I'm fairly certain that Hubrol 'enamels' are now acrylic, rather than the proper alkyd resin enamels that they onece were.

[Ramon WilsonParticipant @ramonwilson3]

Mark – they are still sold as 'enamels' as distinct from their 'acrylic' range. Humbrol sell paints under both descriptions. According to 'e models' they are oil based but whether they are I'm not certain. They are definitely not acrylic as most of us would be aware of as acrylic.

As alluded to previously I've been a long time user and do still have quite a number of old tins (14ml it seems not 13ml ) to call on on the odd occasion.

My view that they are not as good as they used to be is based on the recent painting of two control line models where the paint was 'thin' by comparison and took far too long to dry between coats – remaining vaguely 'sticky' for some days. All done in a good warm environment too.

This is not to knock Humbrol – they've served the modelling community well enough for far to long but the latest 'enamel' is not what it used to be both from a coverage nor drying perspective.

I have never used their acrylic range so can't comment but my preference is for Tamiya and latterly the new AK Real Colour – which I have found to be a very good paint – for what it is designed for

[half whitParticipant @half-whit]

Just reading through the posts in this thread, in particular relating to the quality of humbrol paint

I’ve been using the little pots for donkeys years and have around 15-20 colours. Never had a problem with quality, they all brush well and set hard fairly quickly

Having said that I have just bought a small tin of number 19 bright red and it’s awful. It paints ok but is still tacky after 5 days.

Nothing to do with lack of shaking or stirring or the room temperature.

I’ve lost confidence in the brand now, never again.

Anyone recommend an alternative, perhaps in the Revel range?

Geoff

[Speedy Builder5Participant @speedybuilder5]

Yes the maxim was:-

”          You can put salt on chips but not chips on salt”  –

As Nick Clarke said Synthetic on Cellulose but not Celuose on Synthetic.

Bob

[Dave WoottonParticipant @davewootton]

Geoff

I have had a similar experience recently with humbrol bright red used for lining, my very old tins were fine but some new ones took ages to dry and very hard to keep a consistent line width (bow pen and lining tool). I tried a tin of signwriters enamel and it seems to be just like old humbrol, lots of pigment and covers well, even thinned it and sprayed some buffer beams with it, came out fine, settling out nicely. Mine is by Craftmaster bought via eBay.

[half whitParticipant @half-whit]

Hi Dave

Thanks for the reply, I’ll have a look at the craftmaster range.

I would suggest to all to be wary of the recent humbrol pots with the new label on the lid. Note the spot and circle above the word gloss.

[Dave WoottonParticipant @davewootton]

Ahh thats the type of tinlet that has given trouble and took ages to dry, my old ones had the paint number embossed on the lid. The search is on for some old dusty tins of the good stuff in the other colours I need.

[bernard towersParticipant @bernardtowers37738]

there was old tins of precision paints on a stand at MMEX thurs at £2 a small tin and £5 a BIG tin, bought one or two and the big one had £21.35 on the bottom!!!!!.

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