Jump to content

What the hell is going on here!


Tony Adams

Recommended Posts

I have been noticing paint crazing on some of my recent models that appears around 6 months to a year. Consequently I on my latest model a Trumpeter Attacker I tried a slightly different paint build up. Normally I use Tamiya primer followed by Mr Color acrylic and then sealed with Klear ready for deals with finally a coat of Mr Color Matt Varnish all applied via airbrush.

This time I thought I would give Humbrol's new Gloss acrylic a go, replacing the Klear.

This is the model before application of the Humbrol which I applied yesterday evening

DSC_2716.JPG

All looked fine but when I woke up this morning I was greeted with this!

DSC_2722.JPG

Grrrrr.

Any ideas what is caused this? My suspicions are pointing to the Mr Color or to the warm temperatures we had while the varnish was drying.

Link to comment
Share on other sites

Strike my previous question, I just re-read your post. So this is the Humbrol gloss over the top of the Mr Color acrylic?. Not sure what the problem is there, but your picture jogged the old memory banks. I have had issues using Mr Color in the past, as well.

Wing1a.jpg

Wing3a.jpg

This was their matt varnish over the top of Vallejo Model Air. I suspect Mr Color doesn't play well with other brands. :hmmm:

Link to comment
Share on other sites

Like Tamiya, Mr Color needs a long while to cure before another brand's acrylic paint/varnish is applied over it, minimum 24 hours. How soon after you painted it did you varnish?

Link to comment
Share on other sites

It was about 6 hours for the Dark Grey and over 24 for the Sky ( there was a little crazing on the sky but not so much). This if the first time I've seen this straight away. As I said I have had several occurrences of it happening months after the model is completed which is why I was keen to try something new. Maybe the Humbrol is a little harsher than Klear.

Does leave me in a quandary about whether to use Mr Color in the future , I find it sprays much better than Tamiya or Vallego. I've used it for everything over the last couple of years.

Link to comment
Share on other sites

Jonner's was having identical problems with the new Humbrol clear not so long ago

http://www.britmodeller.com/forums/index.php?/topic/234941974-humbrol-klear-over-gunzegsi-aqueous-hobby

Yep - and I left the Mr Colour for a week to cure. The cracking on mine was smaller and finer. Humbrol Klear over the Tamiya semi-gloss white on the underside ( thinned with mr self levelling thinner, like the Gunze gloss grey on top) was fine however - which is the puzzler.

My theory is its the thinner rather than the paint that Humbrol Klear doesn't like, or rather the residue of the thinner coming out of the paint. I think it takes longer to de-gas from drying Mr Colour than Tamiya and there's a reaction between it and the Klear. I hasten to add thats only a WAG on my part.

Jonners - feeling your pain

Link to comment
Share on other sites

I use Mr Color and Mr Hobby paints 99% of the time and don't have this problem but I don't use Kleer. I use the Gunze gloss products and have never had a problem. Someone else on here had the same problem before Jonners so there does appear to be a bad reaction between Mr Color (or its Thinners) and Kleer/Humbrol Clear. My advice would be to stop using the Kleer/Clear and start using Mr Color or Mr Hobby clear products, they do matte, semi gloss and gloss.

Duncan B

Link to comment
Share on other sites

My advice would be to stop using the Kleer/Clear and start using Mr Color or Mr Hobby clear products, they do matte, semi gloss and gloss.

Duncan B

Vallejo Air Satin and Matt works fine as well.

Link to comment
Share on other sites

I use have used the Alclad aqua gloss over Gunze/Tamiya thinned with cellulose thinners with no problems, followed by Winsor & Newton matt varnish again no problems.Have even thinned the W&N satin varnish with Tamiya X-20A to spray and no problems

I have a bottle of the Humbrol Clear but am a bit apprehensive to use it now, wonder whats in it to cause these problems, as not so long ago it was lauded as the replacement for the old Johnsons Klear

Link to comment
Share on other sites

I've never used the Humbrol stuff and don't intend doing so as I'm happy using Gunze and Vallejo clears.

It may be a combination of using Humbrol and applying it to soon before your paint is fully cured, as has been said Tamiya and especially Gunze take a fair bit of time to go off and if you're using the Levelling thinner it'll take even longer, I give my paint at least a week to go off before thinking about applying a clear coat.

Tim.

Link to comment
Share on other sites

Thanks for the sympathy and constructive suggestions.

I spent yesterday event stripping off the paint (sigh) , In the interest of scientific discovery I intend to follow exactly the same paint build up but this time leave several days before glossing.

It may end in tears again but I prepared to take one for the team!

I will report back ...

Link to comment
Share on other sites

I've never used the Humbrol stuff and don't intend doing so as I'm happy using Gunze and Vallejo clears.

It may be a combination of using Humbrol and applying it to soon before your paint is fully cured, as has been said Tamiya and especially Gunze take a fair bit of time to go off and if you're using the Levelling thinner it'll take even longer, I give my paint at least a week to go off before thinking about applying a clear coat.

Tim.

I generally only leave it 24 hrs before applying my Gunze gloss coat. I'm using the same thinners (regular Mr Color normally) as I did for the paint maybe that is why I don't get any problems?

My bottle of Humbrol Clear will only be used for dipping canopies in after hearing quite a few reports of problems now.

Duncan B

Link to comment
Share on other sites

I think you added the Clear too soon. I don't know how long you took from last coat to Clear, but I've had this happen twice when I've tried to rush things through.

Yes, that's the reason. I had this problem too

Link to comment
Share on other sites

When the paint dries/cures slower than the topcoat, the paint will crack or wrinkle (remember the paint used on dashboards of Triumph and other cars? - similar like that). Probably the same will happen if the topcoat shrinks a lot while curing. I have not tried my Humbrol Clear yet so I cannot tell - but I have one model which I finished years ago and which was sealed with some clearcoat (not Humbrol I think) which strangly cracked up after months... So first of all I too say the undercoat must dry longer before you use Humbrol Clear on this. But as we have no "long time experience" yet, it might also happen on fully cured paint - only some weeks/months later??? So thanks for the warning - I will check on some scrap parts first.

Link to comment
Share on other sites

If anybody is interested I have just written about this , along with other Modelling related things in our club magazine The Romsey Modeller is now available for download at July 2013

FrontPageJuly13small.jpg Contents
  • Club News.
  • Photos from June and July Club Meetings.
  • 9 Peaks Challenge.
  • Old Crow Claymore – Part 2 by Russell Eden.
  • Foden Condor 4×2 Tractor Unit (Part Four) by Nick Burden.
  • Fighting the Tiger by Chris Marston.
  • Crazy Attacker by Tony Adams.
  • Revell/ Matchbox 1/72 Flower Class Corvette Commission build by Nigel Robins.
  • Tamiya 1/48 Panzer IV J by Russell Eden.
  • From our Foreign Correspondent
  • End Note.
Link to comment
Share on other sites

  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...