Weird effect with matt varnish?

[BombTaxi]

Hi chaps

I've just been finishing of my 1/48 scale Hurricane. Paint and decals are on, and about a week ago I sprayed it with gloss varnish. I have just sparayed on the matt varnish to finish it all off, and one wing decal and small areas of paint have started to bubble up and show ridges. This happened staraight away after spraying, but only in small areas. Has anyone else encountered this problem? The model is finished in Humbrol enamels and both varnish sprays are Humbrol as well.

Any advice would be much appreciated

Cheers

BT

 

[Wurger]

Could you take a few close-up pics of the effect?

 

[Sweb]

Is the varnish an enamel or lacquer based product? From your description of the affect it sounds like the varnish attacked the enamel. This is typical of what lacquer will do to enamel. It causes it to dissolve and wrinkle up (lift) dramatically. This can be prevented by waiting for the enamel to completely cure over a period of a couple weeks and then using the varnish in light misting coats with a 6-8 hour wait between coats. A heavy application of the varnish might also be the cause of the problem.

 

[Wurger]

Hum... Bomb Taxi said that he used Humbrol enamels. If these both varnishes are the same like these Humbrol enamels the problem shouldn't have been appeared at all.But if the gloss varnish is the acrylic one and the matt varnish is of enamel kind this might occur.

 

[Airframes]

Given that both varnishes are Humbrol enamel, it might be that the matt varnish hasn't been fully agitated. I find spray cans a pain, and don't often use them, but they DO need to be shaken vigorously for quite some time, in order to 'stir' the paint/varnish. This is even more important with matt varnish, in order to fully mix the matting agen with the carrier. It may be that the thinners in the varnish has not fully mixed in, and has attcked the previous coats. This will be more likely to happen if too heavy a coat is applied, and/or if too close whilst spraying.
Since Hornby acquired Airfix and Humbrol, the Humbrol factory is now no more, and the paints and other products under this once revered lable are now produced elsewhere, and very obviously to different formulations. In my personal opinion, the quality, versatility and life of these products is far inferior to that normally associated with Humbrol products. With this in mind, it is very possible that the formulation of the matt varnish has changed, and this might affect its use, giving the effects described in your post.

 

[Wurger]

I agree with you fully Terry.But the varnish could be drying too fast and as a result it could cause"rippling" to the the previous layer.

 

[Airframes]

Yep, could be that too Wojtek. Again, this might be the thinners in the varnish causing the problem. If not fully mixed, too much thinners will spray, being less viscous than the varnish, and this could cause it to ripple when drying, as it would dry faster due to lack of the main medium being present.
I really do wish that Hornby would find either the original Humbrol formulas, or use a manufacturer who can produce paints and varnishes as good as the Humbrol products. The present products are only just bordering on acceptable, and nowhere near as good as they were.

 

[Wurger]

Yep...anyway it will be very difficult to correct the painting on the model.

 

[BombTaxi]

Thanks for all your replies guys. I think it might be a mix of insufficient agitation and too heavy a coat going on - I'm a novice to spray cans and I haven't quite mastered the balance between too much and not enough yet. At least it wasn't the Seafire, I can live with the Hurricane going a bit wrong, it has always been a bit of an experiment and it wasn't going to win any prizes before this happened anyway

 

[Airframes]

Glad to help BT. Using spray cans is always a difficult business on models, as there just isn't enough control. The gloss varnish is probably OK, but matt, due its nature is more tricky. Try using the following for matt, as it can be applied by paint brush, without leaving brush marks. Experiment first though.
Use Johnson's Klear, and pour enough for the job into a small container or jar. Add a little Tamiya acrylic Flat Base, and stir well. Try it on a piece of scrap, and wait for it to dry, which doesn't take long. If it is not matt enough, add a little more Flat Base and repeat. If too much Flat Base is added, it will dry with either a milky appearance, or with chalky looking 'dust' present. The latter is far too much Flat Base, the former just a little too much. To correct, add a little more Klear.
Not a very precise 'recipe', but it works, just needs a bit of trial and error.
Brush onto the model, ensuring the brush is not overloaded, and lay it off properly. (brush out until more required), ensuring the brush strokes go one way only. Leave to dry. If any 'pools' appear, or drips form on trailing edges or other sharp areas, use the edge of a piece of tissue to soak up.
Once dry, as Klear is self-levelling, it should look uniform and free of brush marks, and will give a good matt appearance. The sheen can be varied up to semi matt or semi gloss by the addition of more Klear.

 

[BombTaxi]

Thanks Terry, I will give that a go. Can you get this Klear stuff from the supermarkets? I understand it's some kind of industrial cleaning product...

 

[Airframes]

Yep, you'll find it with cleaners and polishes etc in Tesco, Sainsbury's and so on. It's actually a floor polish! You'll probably have noticed that many modellers use it as a gloss coat, and for fixing transparent parts. It's also used to coat canopies, to give a sparkling clear look.
Just one thing, the last time I bought some, about January, Tesco didn't have it, but Sainsbury's did, in the original clear bottle, with a red and blue lable. I believe it's now changed its name to Johnson's Pledge Klear, in a white bottle I think. It's about £2 for a 500ml bottle, less than the price of a 14 or 25ml bottle of modelling acrylic varnish!
Should last you ages mate!
Your local model shop should have the Tamiya Flat Base, which is white, and fairly thick.

 

[BombTaxi]

Cheers Terry, I'll pick them up when I next have a kit ready for matt coat 8)

 

[109ROAMING]

Many thanks also Terry -Got the 'Klear' stuff ,just gotta buy this tamiya acrylic flat base

In terms of mix what would you recommend starting out with? a 50/50 mix?

 

[Airframes]

OH NO! Start about 90% Klear, 5% Flat Base. You're certain to need more Flat, but it won't even be near 30% at a guess.
It does take a bit of trial and error, but as it dries good enough to see the effect in a very short time, it's not a problem. I normally mix-up a batch, then keep it in an old Tamiya paint jar or similar. At a guess, without actually doing it to check, a 10ml Tamiya bottle would need around 4 good 'blobs' from a No3 size paint brush, but you'd have to check as you go along. Make sure the Flat Base is well mixed in, and stirred, and stir before use EVERY time you use it.

 

[109ROAMING]

Many thanks Terry! sounds like fun ....more like its gonna end in disaster knowing me

Will give it my best though

 

[Airframes]

You're welcome Daniel. Once you find the right mix, it'll work OK. You shouldn't have problems, it's 'Daniel Proof'!!

 

[109ROAMING]

Hope your right mate