Issue with GSI MR colour am I alone...

[SaintsPhil]

I had a strange issue with Mr Color paints a while ago this time last year actually) can't remember if I posted about it or not, but it went away so I forgot about it...it seems to have reoccurred...

The issue I have is that the paint seems to dry 'washed out' like very heavy grey fading. I'm wondering if it's a temperature/humidity issue. I spray outdoors in the shed, was previously a garage but the conditions are similar. Previously I thought it was reacting with the primer, but this time I sprayed direct onto bare plastic and got the same issue. Has anyone else had this issue?

I'll add a photo later when home.

Thanks

Phil

Edited November 19, 2014 by SaintsPhil

[Steve Noble]

Is it the Mr Color lacquer or Mr Hobby Aqueous stuff..?? A picture would help. I use the Mr Color lacquer type paint most of the time and have never had any problems with it..

[Tom Hall]

Do you have a moisture trap on the hose? Is the shed temperature 65-80 degrees F., including at the compressor? Is the humidity of the shed reasonable? (Getting a milky grey cloudiness in the paint also occurs with acrylic lacquer for automotive use. I have even seen it on a car fresh from the factory. It won't buff out. You may want to search the Internet for more info on that phenomenon. I suspect it's the same one as you had.)

Edited November 20, 2014 by Tom Hall

[Rich G]

I us the Mr Hobby Aqueous which uses the laqcuer base and I use the Laqcuer thinner with no issues, it's lovely stuff perfect for airbrushing. I've not seen any fade at all.

I would think it could be a humidity/temperature issue, but I've not experienced any myself, in the UK it doesn't exactly get humid!

Rich

[colin]

what are your thinner to paint ratios

[SaintsPhil]

Thanks all for the input so far, I went out to the shed last night to take a second look and the results are worse! Normally I walk away for a while, come back and it's never as bad as you first think....

It was Olive Drab, MR color version, thinned with Levelling thinners to my usual consistency. As I said I almost exclusively use these paints so it's not a first time user issue I don't think...the OD has drive to almost a zinc chromate colour it's that washed out! I'll take a snap later.

I'm convinced now it's a temperature/humidity issue, especially after searching the net as suggested above. It's was cold out when I sprayed Id say less than 10degC but above 0 and a slight mist in the air.

Phil

[colin]

It seems a strange one Phil, only had a problem with Humbrol enamels when I over thinned them with Cellulose thinners and they looked washed out and almost powder like.

Never had a problem with the Mr Hobby aqueous paints when thinned right down, have the Mr Colours but not tried them yet.

Have you drained the tank (presume you have one) on the compressor.

Have heard of blooming when spraying paints when cold/humidity but never washed out colour looks like it as you say, cold and damp air, heater needed for the shed now winters here then

[Tom Hall]

Phil, less than 10 degrees C. is the problem. (That's below 50 degrees F.) Your paint would need a parka and mittens. I think your problem will go away if you spray and let the paint dry in a place that's 65-80 degrees F.

Edited November 20, 2014 by Tom Hall

[SaintsPhil]

Ah ok it's temperature then

Here's the pictures by the way

The inside of the engine bay is unpainted OD plastic for reference..

The more I look at it the more I kind of like the effect though...

Edited November 20, 2014 by SaintsPhil

[Rich G]

It's faded out like you see on aged OD vehicles and aircraft, the real stuff did fade over time, although it doesn't sound like the effect you were originally after. I would think that if you're in the UK with the colder weather at the moment that might affect the drying time and the like, it might just be the batch of paint. I had some issues with a humbrol Olive drab tin giving patchy results bought a new one and it was completely different.

Rich

[SaintsPhil]

Well funnily enough it will be a well used truck by the end, hence I wasn't that upset by the finish! I may well go back over with another coat though. Yes I'm in the UK and it was a brand new jar, so it could be a batch thing I guess. I'll try again tomorrow afternoon when it's a touch warmer.

[Tom Hall]

Hello again, Phil. Would be curious to know the results of your latest spraying.

I am a long-term student of Japanese. For practice, I summarized your situation in an email to Gunze Sangyō (which is a very large chemical and textile company) to ask them about (1) whitish cloudiness drying in airbrushed Mr. Colour paint (which maybe does not describe the phenomenon you experienced very well) and (2) whether they could tell me the maximum and minimum room temperatures and humidity for airbrushing Mr. Colour.

I received their reply yesterday. It is four paragraphs, the first of which is greetings, felicitations and summary of my inquiry. I shall translate most of the rest:

"We have not especially set any optimal figures regarding temperatures and humidity. When room temperature is low, it will influence the length of time required for the paint film to dry and so on, but basically there is no change to the properties of the paint.

In addition, regarding your reference to the surface of the paint becoming cloudy white, we believe this is the phenomenon called "blushing". When humidity is high, room temperature falls, there is dew, etc., the moisture in the air reacts with the paint and it may become whitish, mottle, or do other things. If one paints on days of good weather and low humidity, one can largely prevent that sort of phenomenon. It is difficult for us to measure with certainty exactly what percentage of humidity below which this will not happen, therefore we have not set any particular statistical limits. We very much regret that this reply may fall short of your wishes and ask for your understanding."

They close by suggesting a product line called Kreos, and invite that if you notice anything else about the phenomenon or have suggestions, please don't hesitate to contact them.

Compare Gunze's reply to the statistics that some automotive paint manufacturers publish regarding maximum and minimum temperatures for both spraying and drying. I'd say Gunze has left itself quite a bit of wiggle room.

Edited November 25, 2014 by Tom Hall

[SaintsPhil]

Tom,

Thanks for taking the time to approach GSI that's much appreciated! It does all make sense now it was a cold foggy night so I assume the combination of the 2 caused the blooming. It's nice to know there's a real explanation to these things, mainly so I know what not to do next time!

As for further spray, against my better judgement I switched to Vallejo and tried their OD primer over the top. The results were better, a pleasant surprise! I got a bit of beading on the surface but the primer has dried to a nice smooth finish. There is a touch of 'washing out' in the corners of a few parts but I think that was me over thinning the paint rather than the same issue. I know have an OK base to heavily weather on top of. Glad it was an AFV kit not a key I learnt this lesson on!

Thanks again

Phil