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.

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.

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 – 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

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