Matt varnish has not set

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ge_rik
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Matt varnish has not set

Post by ge_rik » Mon Sep 02, 2019 7:00 pm

I painted some figures with acrylics and decided to give then a coat of matt varnish. Big mistake! The varnish is still tacky two years afterwards.

Any suggestions?

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Re: Matt varnish has not set

Post by -steves- » Mon Sep 02, 2019 9:00 pm

WOW, that's some time you gave it to dry, lol :lol:

I had a similar thing with some resin moulds I made once, they never did dry, lol :thumbleft:
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Re: Matt varnish has not set

Post by Peter Butler » Mon Sep 02, 2019 10:04 pm

Sometimes varnish seems to separate, similar to a can of paint left standing for a long time.... a skin forms leaving only the thinners/solvent which will not set without the pigment.
Perhaps another coat (of fresh varnish) over the existing one will encase the tacky surface?
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Re: Matt varnish has not set

Post by philipy » Tue Sep 03, 2019 6:13 am

Perhaps it is simply that they are part of Peckforton's criminal element, with 'sticky fingers' ?

OK, I'll be off now! :lol: :lol:

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Re: Matt varnish has not set

Post by ge_rik » Tue Sep 03, 2019 6:49 am

Peter Butler wrote:
Mon Sep 02, 2019 10:04 pm
Sometimes varnish seems to separate, similar to a can of paint left standing for a long time.... a skin forms leaving only the thinners/solvent which will not set without the pigment.
Perhaps another coat (of fresh varnish) over the existing one will encase the tacky surface?
Thanks Peter. This was a well shaken aerosol - at least I think (hope) I shook it well. I might try giving one of then a dusting of talc before over-coating with a different varnish, I'll also try another with just a coat of varnish to see what happens.

Annoying that they were the figures I was really pleased with their finish and thought the varnish would protect them..... :x
What I don't understand is that the varnish set well initially and just seems to have become sticky over time.
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Last edited by ge_rik on Tue Sep 03, 2019 6:56 am, edited 2 times in total.
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Re: Matt varnish has not set

Post by ge_rik » Tue Sep 03, 2019 6:50 am

philipy wrote:
Tue Sep 03, 2019 6:13 am
Perhaps it is simply that they are part of Peckforton's criminal element, with 'sticky fingers' ?

OK, I'll be off now! :lol: :lol:
If only it was just their fingers...... :?

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Re: Matt varnish has not set

Post by DonW » Tue Sep 03, 2019 8:16 am

My first thought was if the varnish set initially possibly something given off by the resin has softened it. However the very good paint job seems unaffected. Perhaps ome kind of fumes have passed through the paint layer then affected the varnish . Perhaps the affect happens at the surface on meeting the air. Odd things do happen. Some electric cables become full of green goo due to migration of plasticisers so possible something is happening here.

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Re: Matt varnish has not set

Post by Lonsdaler » Tue Sep 03, 2019 8:23 am

I bought some Humbrol spray varnish, and then noticed when it arrived that it is not suitable for use over acrylic paint. Could it be a similar issue?
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Re: Matt varnish has not set

Post by ge_rik » Tue Sep 03, 2019 1:13 pm

Lonsdaler wrote:
Tue Sep 03, 2019 8:23 am
I bought some Humbrol spray varnish, and then noticed when it arrived that it is not suitable for use over acrylic paint. Could it be a similar issue?
Maybe. I've just experimented - put talc on one and then varnished it and tried another with a fresh coat of varnish. Just have to wait and see.

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Re: Matt varnish has not set

Post by GTB » Wed Sep 04, 2019 4:34 am

ge_rik wrote:
Mon Sep 02, 2019 7:00 pm
I painted some figures with acrylics and decided to give then a coat of matt varnish. Big mistake! The varnish is still tacky two years afterwards.

Any suggestions?
Change to another brand of clear coat......

I've had no end of trouble with clear finishes off and on over the years.

I used Humbrol Matt Cote and Satin Cote for many years, but when Hornby took over Humbrol they lost the plot. About the time I retired and moved into Garden Scale my last bottle of Satin Cote ran out and the replacement was made in China.

It was used on the first of my passenger car models and while it was touch dry overnight, it never really set hard. If you picked up the models and held them in a tight grip the clear coat would soften slightly with the heat in my fingers and have a very slight tacky feel to it. I noticed late last year that the finish had finally hardened, it only took 5 years, almost to the day..... :roll:

I haven't used any clear coat made by Humbrol on a model since then. I bought a bottle of Satin Cote to test after production moved back to the UK, but it was still the same. The polyurethane varnishes that Humbrol sell in tinlets has also changed and I stopped using that when my last tin of 'real' Humbrol ran out.

The enamel colours dry OK, just not the clear finishes. My problem with the colours is that the colours were once extremely stable from tin to tin over decades. When Hornby took over, a lot of the colours changed noticeably. I haven't bought a tin, or bottle of Humbrol clear finish for at least five years years, or their enamel tins for about two years.

I've currently standardised on Revell enamels. The Revell clears soften with heat, but the enamel colours are stable at steam loco temperatures, so I use the enamels on all models and use a locally made brand of hardware store satin varnish as the final clear coat on garden scale models. It sets rock hard in a couple of days and doesn't soften on steam locos.

Revell don't do a satin clear, so I mix their matt and gloss clears 1+1 to get a satin finish. I'm still using the Revell clear finishes for HO models as heat isn't an issue. Revell clears have some strange characteristics when spraying though and I may yet change to the hardware store varnish for all clear finishes.


I don't understand the mechanism, but Humbrol aren't alone in selling clear finishes that can take geological time scales to completely harden. Now that I'm retired and have no chem lab access, I just spray a test panel until I find a brand that gives me the results I want. It isn't a recent problem, I've got a couple of HO models that were painted in the late '70s, which was the last time I used a spray can on a model as it happened. The finish did eventually harden completely, but it took 20+ years.

Remember though that I regard spray cans as an invention of the devil and use an airbrush for all my model painting, so none of these ramblings may be related to your problem with the paint finishes you used.

Waterborne acrylics are lacquers and dry by evaporation of the water and solvents, but varnishes are more akin to enamels and dry by crosslinking the resins on exposure to air. The two types can interfere with each others drying mechanism and the solvents used in some types of paint can attack other paints.

With so many paint finishes available and unknown incompatibilities between them, all you can do is test various combinations until you find one that works for you.


Regards,
Graeme

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Re: Matt varnish has not set

Post by idlemarvel » Wed Sep 04, 2019 7:00 am

Very informative Graeme thanks.
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Re: Matt varnish has not set

Post by ge_rik » Wed Sep 04, 2019 7:19 am

Thanks Graeme
I've decided to stick (ooops, unintended pun) with Vallejo paints and varnish for my future figure painting. Our wargaming brethren know a thing or two about figure painting and swear by (rather than at) Vallejo products. They are not the cheapest but it certainly seems you get what you pay for in this area.

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Re: Matt varnish has not set

Post by GTB » Wed Sep 04, 2019 9:53 am

ge_rik wrote:
Wed Sep 04, 2019 7:19 am
I've decided to stick (ooops, unintended pun) with Vallejo paints and varnish for my future figure painting.
A friend of mine who started out as a military modeller before converting to railway modelling swears by Vallejo paints. I seem to recall he was also impressed with the acrylic clear finishes that are sold by Microscale, but can't remember if he used them with Vallejo colours.

The military modellers can also teach us a thing or two about painting models. I learnt more from a couple of military modelling books on finishing models than I ever had from railway modelling books.

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Re: Matt varnish has not set

Post by -steves- » Fri Sep 06, 2019 9:33 pm

I also use Vallejo acrylics and get on very very well with them for airbrushing. :thumbup:
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