MCW paint issues

[Jon Haigwood]

I have been building about 8 Shelby Cobras in deferent variations. I have been using MCW laquears exclusively. The first first 4 turned out great, some with painted stripes. On the next 4 I can't seem to get a smooth finish, it comes out a bit rough. I am using the same airbrush, air pressure and technique the only difference is the temperatures are a bit colder , about 60deg and there has been more rain. Mike at MCW thought the temperatures may have something to do with it. Has anyone had this happen ?        

[Monty]

I'd like to know when the first four were painted vs the rest.  Temperature may have been a factor if the first four were painted in a warmer month and these were painted fairly recently.  I've noticed several builders on here paint a lot of bodies during the summer and finish the cars later.  

That said, I wonder if using Mr Hobby Leveling Thinner might alleviate that issue.  

[Can-Con]

My guess would be the weather, Jon.

Cooler air holds more humidity and that can be a factor. 

I'd wait for drier weather. Humidity is much more of a factor with these things then just temperature. The drier the better.

 

Edited December 1, 2023 by Can-Con

[Jon Haigwood]

1 hour ago, Monty said:

I'd like to know when the first four were painted vs the rest.  Temperature may have been a factor if the first four were painted in a warmer month and these were painted fairly recently.  I've noticed several builders on here paint a lot of bodies during the summer and finish the cars later.  

That said, I wonder if using Mr Hobby Leveling Thinner might alleviate that issue.  

The first 4 were painted just a couple weeks before the weather got colder and wetter. I think I will hold off painting any more until the weather improves. Until then I have some other parts to put together and some sanding to do. 

Edited December 1, 2023 by Jon Haigwood

[peteski]

1 hour ago, Can-Con said:

My guess would be the weather, Jon.

Cooler air holds more humidity and that can be a factor. 

I'd wait for drier weather. Humidity is much more of a factor with these things then just temperature. The drier the better.

 

I live in the Northeast USA and we are currently entering the winter months. The cold air is much more drier and holds much less moisture than warm summer humid air.  Easy way to observe that (other than looking at the hygrometer) is getting static electric zaps everywhere I touch. That is because dry air does not allow the static electricity to dissipate. That is why I prefer casting and painting in the cooler months. No worries about moisture absorbed into urethane resin causing bubbles, or paint blushing due to ambient moisture condensation.

But colder ambient temperature does usually increase the viscosity of liquids (like paint), so the temperature alone could be contributing to this paint issue.

Edited December 1, 2023 by peteski

[Can-Con]

12 hours ago, peteski said:

I live in the Northeast USA and we are currently entering the winter months. The cold air is much more drier and holds much less moisture than warm summer humid air.  Easy way to observe that (other than looking at the hygrometer) is getting static electric zaps everywhere I touch. That is because dry air does not allow the static electricity to dissipate. That is why I prefer casting and painting in the cooler months. No worries about moisture absorbed into urethane resin causing bubbles, or paint blushing due to ambient moisture condensation.

But colder ambient temperature does usually increase the viscosity of liquids (like paint), so the temperature alone could be contributing to this paint issue.

Peter, I can guarente you I live more north and more east then you do, and I don't even know where in the States you live. ?

[James2]

1. Same prep?
2. Same Primer?
3. Same spay location?
4. Painting during rain can bring moisture into effect.
5. Do you have moisture trap on your set up?

[Classicgas]

You might want to consider a dehumidifier, especially in the area you paint in.

[Jon Haigwood]

2 hours ago, James2 said:

1. Same prep? 
2. Same Primer? 
3. Same spay location? 
4. Painting during rain can bring moisture into effect. 
5. Do you have moisture trap on your set up? 

1. Same prep? yes
2. Same Primer? yes
3. Same spay location? yes
4. Painting during rain can bring moisture into effect. , Currently 85 percent humidity 
5. Do you have moisture trap on your set up? yes

Edited December 2, 2023 by Jon Haigwood

[R. Thorne]

Do you paint outside?

[Chariots of Fire]

Did you happen to do anything to the primer coat on this one that you did not do on the first 4?  It almost looks like there was a wax like coating on the surface that caused the paint not to smooth out.

[Jon Haigwood]

1 hour ago, R. Thorne said:

Do you paint outside?

No but the area is not heated well and open to some outside elements

[Jon Haigwood]

1 hour ago, Chariots of Fire said:

Did you happen to do anything to the primer coat on this one that you did not do on the first 4?  It almost looks like there was a wax like coating on the surface that caused the paint not to smooth out.

Same as others, Paint was smooth after spray but mottled after as it was drying 

Edited December 2, 2023 by Jon Haigwood

[R. Thorne]

Get yourself one of these and place it near where you paint as it is difficult to gauge relative humidity accurately by guessing.  Also, I don’t hook up my exhaust fan to the window until I am ready to paint.

[Dpate]

6 hours ago, Jon Haigwood said:

1. Same prep? yes
2. Same Primer? yes
3. Same spay location? yes
4. Painting during rain can bring moisture into effect. , Currently 85 percent humidity 
5. Do you have moisture trap on your set up? yes

I can't say for sure that the humidity caused that issue, but 85 is way to high.  I'm not sure how you even sit in that to even paint lol. Certainly need to get your painting area a little more controlled, and get the humidity down though.  85% there's a ton of moisture in the air, and the best way to combat that is a dehumidifier. 30%-55% is ideal living conditions.  What's your humidity when it's not raining? 

[Shark]

Stupid question: are you sure the last ones are lacquer? He is transitioning to enamels. The only time I have had finishes like that were using enamels. I prefer lacquer, if you use it in higher humidity it usually blushes or milks up.

[Jon Haigwood]

1 hour ago, Shark said:

Stupid question: are you sure the last ones are lacquer? He is transitioning to enamels. The only time I have had finishes like that were using enamels. I prefer lacquer, if you use it in higher humidity it usually blushes or milks up.

Yes they are all lacquer, I tried the enamel and didn't much care for it. I also used the MCW lacquer primer and lacquer clear 

[Jon Haigwood]

2 hours ago, Dpate said:

I can't say for sure that the humidity caused that issue, but 85 is way to high.  I'm not sure how you even sit in that to even paint lol. Certainly need to get your painting area a little more controlled, and get the humidity down though.  85% there's a ton of moisture in the air, and the best way to combat that is a dehumidifier. 30%-55% is ideal living conditions.  What's your humidity when it's not raining? 

I never checked the humidity before. It will be awhile until it stops raining. I will check it when the time comes.

 

[Shark]

2 hours ago, Jon Haigwood said:

Yes they are all lacquer, I tried the enamel and didn't much care for it. I also used the MCW lacquer primer and lacquer clear 

Sorry I couldn't help. Never seen lacquer do like that, so I am interested in what the cause may have been.

[Skip]

First, have you contacted MCW with pictures and details of your application methods? MCW is a "small" operation compared to big name paint manufacturers, so I would think that you can expect an answer and or some sort of remedy to your paint issue. That would be my first email, rather than trying MCW in the court of popular appeals; not that you can't expect a remedy here. I would give the manufacturer / distributor first shot though.

Second, to me, your picture doesn't indicate a humidity issue, there is no flush to that paint at all it has reacted to something and is somewhat shiny. If it were smoother, it might be rubbed, or color sanded out.  My bet is one or two wetter undercoats in rapid succession which were not fully flashed off followed by a quick heavy topcoat which the solvent reacted through to the primer, maybe under the primer to the plastic. 

Test it: If you have any of the paint, left try shooting a couple of spoons or a small, primed panel to see if you get any reaction to the same prep, same paint procedures and similar shop conditions.  

Tip: If you can get the free Formica 2" X 3" samples at your local home center, pick up a few of the smoother ones, sand the color side with 600 - 800 grit then prime and paint them as paint test panels. The dehydrator won't affect them, (the paint sands off easy enough for reuse). Just don't tell the countertop salesperson what you're using them for and don't take so many so often that you're being a pest. 

[James2]

^^^^^^ Mike is usually very friendly and helpful, his shop was local to me before the move.^^^^^

[Jon Haigwood]

Yes I emailed MCW, Mike wrote in a reply that cold weather could be a cause for this. On MCW's application guide it states to paint wet coats from 2 to 3 inch's. You can spray additionally coats without waiting for it to dry. This i did same as all the bodies before leaving a fully smooth glossy finish. The only differences in the process was the cold wet weather. This time it was smooth and glossy until it dried. Drying was done in a dehydrator  

[James2]

One thing is for sure, you won't be the first to strip a body down and start over....

[peteski]

On 12/2/2023 at 7:26 AM, Can-Con said:

Peter, I can guarente you I live more north and more east then you do, and I don't even know where in the States you live. ?

Regardless of where we live, what I stated is accurate.  Northeast USA (New England) is Vermont, New Hampshire, Maine, Massachusetts, Connecticut, and Rhode Island.   I was just making a point that spraying paint cools it down.  If this is done in a hot and humid environment, that cooling spray effect will condense water from the air onto the object being painted, ruining the paint job. If the ambient air is cool and much drier, there is not enough moisture in the air to condense, so no damage is done.  I have experienced this enough so I know not to spray paint during hot and humid days.

Reviewing this discussion now, this specific problem could be humidity related after all. 85% RH seems quite high, but we also  don't know the air temperature of when the painting took place.

Edited December 3, 2023 by peteski

[Can-Con]

10 minutes ago, peteski said:

Regardless of where we live, what I stated is accurate.  Northeast USA (New England) is Vermont, New Hampshire, Maine, Massachusetts, Connecticut, and Rhode Island.   I was just making a point that spraying paint cools it down.  If this is done in a hot and humid environment, that cooling spray effect will condense water from the air onto the object being painted, ruining the paint job. If the ambient air is cool and much drier, there is not enough moisture in the air to condense, so no damage is done.  I have experienced this enough so I know not to spray paint during hot and humid days.

Reviewing this discussion now, this specific problem could be humidity related after all. 85% RH seems quite high, but we also  don't know the air temperature of when the painting took place.

Peter, I was just goofing around, hence the winky face. ?

But, I do know what you mean. I've had a few paintjobs as well as some resin pours ruined because of humidity.