Fog in my paint...

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

AfterBurners

Well-Known Member
TRF Supporter
Joined
May 8, 2012
Messages
8,180
Reaction score
682
Location
Southern Calif
I know this is a common topic, but thought I would get some feed back from you guys/gals on TRF. Currently painting my SUMO and trying to do a cool muti-color paint scheme. Can't wait until it's done. Initially I had painted the red portion of the scheme and had both fins exposed and what happened is I ended up getting over spray on them. So I came back and hit them real quick with 600 to knock the roughness down and followed with 1500 (both sides). I used compressed air to dry them and waited a couple days before repainting, but this time I decided to paint them one at a time to avoid the over spray so only one fin is exposed. First fin turned out great, no over spray, but got some fog in the paint.

This has happened to me before, but not this bad. My fix has always been to wet sand the fin with 800-1000 let the rocket dry and shoot several lite coats of clear coat on it. It seems to turn out nice.

2014-06-11 05.53.53.jpg2014-06-11 05.54.10.jpg

Why does the paint fog? I heard it's from moisture in the air, but here in Cali the humidity isn't bad. I sprayed a few lite coats and then wet the paint on the last couple. I didn't get any runs so I know I wasn't putting it on that heavy. So what actually happens to this fog when you wet sand it. I know it disappears, but beneath it is still color right? I'm debating to spray another coat later?

Sometimes when I paint over primer I don't get this at all. Paint flows nicely and dries with no fog like finish.

I was using Duplicolor Enamel Paint.
 
You mention using Compressed Air to dry it. Is it possible that there was any Oil in that Air?
On the other Hand, you say that you are just painting in your normal Routine, so maybe it's a bad Batch of Paint?
 
You mention using Compressed Air to dry it. Is it possible that there was any Oil in that Air?
On the other Hand, you say that you are just painting in your normal Routine, so maybe it's a bad Batch of Paint?

I used the air from a can like you would use on your computer and never thought of it being a bad batch? Sometimes Duplicolor enamel does this. I always use lite coats, but sometimes and not often if I wet the paint and try to flow it... it will fog. I've noticed when the fog isn't that bad it actually clears or evaporates over a couple days. I don't why, but it does.

Like I said before, for now on I'm going to paint the fins on all future builds one at a time after spraying the body tube first.
 
A couple things can cause fogging. Most common is spraying in a high humidity environment---you already knew that---consider what time of day you are spraying. Even in a hot dry area you can get fogging---in the morning you are closer to dew point. Also laying paint a little thick can cause this---more common with laquer based paints. This is because the laquer paint drys from the inside out---sort of--anyway, it will flash over and trap the solvents/carriers under the top layer for a while. Usually over time this flash fog will go away as the paint cures. It is usually in the top layer of the paint in the clear that floats up and does not change the underlying color. Simply scuff it and respray or--most of the time----not always-----you can simply reclear over it and the problem will go away. Painting a warm surface helps. I usually let my stuff sit in the sun for a few minutes--not too long --and then spray. If I can spray in the sun , all the better.
 
A couple things can cause fogging. Most common is spraying in a high humidity environment---you already knew that---consider what time of day you are spraying. Even in a hot dry area you can get fogging---in the morning you are closer to dew point. Also laying paint a little thick can cause this---more common with laquer based paints. This is because the laquer paint drys from the inside out---sort of--anyway, it will flash over and trap the solvents/carriers under the top layer for a while. Usually over time this flash fog will go away as the paint cures. It is usually in the top layer of the paint in the clear that floats up and does not change the underlying color. Simply scuff it and respray or--most of the time----not always-----you can simply reclear over it and the problem will go away. Painting a warm surface helps. I usually let my stuff sit in the sun for a few minutes--not too long --and then spray. If I can spray in the sun , all the better.

It was closer to evening when I spray say around 6:30, but still with plenty of sunshine. The rocket wasn't in the sun, but both can and rocket were at room temperature or there abouts. Instead of repainting I'll just wet sand it with say some 800 or 1000 since tthe underlying color will not be affected. Then I'll shoot a clear over it. Of course I'll have the whole rocket wet sand before I do this process.

This is enamel, so maybe I did get closer than usual, but like I said the paint didn't run so I'm assuming I was at the right distance.
 
I also have had this happen. My advice, give it a good 4-7 days to fully cure, wet sand with 400-600, let stand a few more days and re-spray. If after wet sanding, you notice the "paint" smell about knocks you over - you probably went too thick and trapped some gas under the surface as others here already mentioned already. I am also terribly impatient when it comes to paint :)

Another thing to look into, if you live close to an airport, see if they have a METAR station there - pilots use them for current conditions (humidity) and some update as often as every 20 minutes - I usually stay under 40 percent for when I paint. If not, a humidity gauge of some sort may be a good investment for you. Humidity can vary a good bit within a relatively small area - until I really started checking, I found it was much more humid when I painted than I thought it was. Good luck, still looks like you do pretty good work !
 
I also have had this happen. My advice, give it a good 4-7 days to fully cure, wet sand with 400-600, let stand a few more days and re-spray. If after wet sanding, you notice the "paint" smell about knocks you over - you probably went too thick and trapped some gas under the surface as others here already mentioned already. I am also terribly impatient when it comes to paint :)

Another thing to look into, if you live close to an airport, see if they have a METAR station there - pilots use them for current conditions (humidity) and some update as often as every 20 minutes - I usually stay under 40 percent for when I paint. If not, a humidity gauge of some sort may be a good investment for you. Humidity can vary a good bit within a relatively small area - until I really started checking, I found it was much more humid when I painted than I thought it was. Good luck, still looks like you do pretty good work !

Excellent advice! I'll wait a few days no rush. It's not like I'm gonna fly it tomorrow and there still needs to be a lot of work done on it. As far going too thick I spray a couple lite and quick tack coats not really worrying much about appearance and then came back after waiting and "wet/ flowed" the paint and that when I noticed after a few minutes start to fog. I went ahead and applied another coat because as I mentioned I plan on wet sanding this rocket. Maybe the air was a little damp, yesterday morning was pretty overcast and like they say June gloom so maybe some perticipation was still lingering? Bottom line - If you don't have a booth with control temps and air enviroment issues will always come up. I think I would be a decnt painter under better circumstances, but hey that would apply to all of us.
 
Often overlooked is the "dew point". Depending on the temp....humidty.....time of day<the dew point varies.

if it is 7-8 degrees or less do NOT paint. your finish will blush.

To expound with out getting technical. Out side temp is 78.......dewpoint is 72 78-72=6 do not paint.

AS eveniing approaches the dew point temp gets closer to the temp. Early morn till 9-10 also. The problem is exacerbated in spring & fall when ground temps interacting will air temp are changing. Fronts passing through also
The only way to tell is check your weather. There are other causes... but this ones a biggie often overlooked.


See the screen shot below for S Cali...below....it's easy to find. Right now it should be close to 3.00 out there and as the day progress's it's going to get worse. Obviously the humidity [for painting[ is much worse than you thought. [71% now] you don't feel it but it's there. All the new paints don't have the same quick dry solvents they used to & the aerosol mist pulls the moisture out of the air onto the surface, where it gets trapped, can't escape and ruins the finish. The result is like white/grey water marks on fine furniture, when you don't use a coaster. [result not the process] If you wipe up the water right away, furniture won't mare...if the moisture could escape from surface of rocket it would be fine.... but the newer paints take so long to cure it's trapped.
I want a 15-20 spread just to be safe. I find it best to paint outside between 11-3.

I have rattle-canned rockets outside in 40 degree temps when there was 10-15% humidity and got away with it.

Google it for the complex definition

Ps I did this for 28 yrs commercial painting. Most outside.

Right now in San Diego the outside temp is 66.... dew point is 57. 66-57=9 For me No painting anything gloss

Other screen shot is US Airnet aviation forecast, it gives a 3 day forecast easier to figure {orange burg Sc]


Ps just re-read your post & noticed the time of 6.30 ish........ well, there ya go!

Screen Shot 2014-06-11 at 5.33.48 PM.jpg

Screen Shot 2014-06-11 at 5.38.38 PM.jpg
 
Last edited:
I recently had the dreaded wrinkle issue with Duplic-color Acrylic Enamel. Others on the form suggested it was caused by off-gassing of the previous layers due to laying down my clear too soon (4 days) after my last coat. So as other posters on this thread suggested enamel, especially acrylic based enamel needs time between coats. I called their support and the recommended time to cure is 7 days. So although the symptoms are not the same waiting between coats is key using these paints. I have had cloudy clear but with Rustoleum only and I am pretty sure in my case it was due to humidity.

I know have the following protocol, paint 2 light layers, 1 medium, let dry 3 hours before handling it, leave for 2 days, wet sand 400 - 600 depending on the coats, clean and leave for the balance of 7 days min, then repeat. So far using this protocol I have not had any issues, although I need to invest in a temp humidity gauge as right now it's by feel.

Realistically although I am now getting good results waiting a week between coats, touch ups, etc. it is not a very efficient system. So I just picked up a compressor to go with the gravity fed spray gun I picked up a while back but have been to chicken to get into. My plan is to get some comfort with the Duplic-color 123 system, which is lacquer based and apparently you can paint, clear, do whatever with minimal times between coats, re-coats, etc.

By far there is much to learn when it comes to getting good results with finishing!
 
A couple things about clear--which I'm moving away from---I tend to lay clear over wet or tacky paint-takes care of the wrinkle problem and there's no waiting days with the chance it could happen anyway !! One other thing, if it fogs, ---I let it tack off and go right back over it again --most of the time--99%--the fog is gone and no ill effects.
 
Often overlooked is the "dew point". Depending on the temp....humidty.....time of day<the dew point varies.

if it is 7-8 degrees or less do NOT paint. your finish will blush.

To expound with out getting technical. Out side temp is 78.......dewpoint is 72 78-72=6 do not paint.

AS eveniing approaches the dew point temp gets closer to the temp. Early morn till 9-10 also. The problem is exacerbated in spring & fall when ground temps interacting will air temp are changing. Fronts passing through also
The only way to tell is check your weather. There are other causes... but this ones a biggie often overlooked.


See the screen shot below for S Cali...below....it's easy to find. Right now it should be close to 3.00 out there and as the day progress's it's going to get worse. Obviously the humidity [for painting[ is much worse than you thought. [71% now] you don't feel it but it's there. All the new paints don't have the same quick dry solvents they used to & the aerosol mist pulls the moisture out of the air onto the surface, where it gets trapped, can't escape and ruins the finish. The result is like white/grey water marks on fine furniture, when you don't use a coaster. [result not the process] If you wipe up the water right away, furniture won't mare...if the moisture could escape from surface of rocket it would be fine.... but the newer paints take so long to cure it's trapped.
I want a 15-20 spread just to be safe. I find it best to paint outside between 11-3.

I have rattle-canned rockets outside in 40 degree temps when there was 10-15% humidity and got away with it.

Google it for the complex definition

Ps I did this for 28 yrs commercial painting. Most outside.

Right now in San Diego the outside temp is 66.... dew point is 57. 66-57=9 For me No painting anything gloss

Other screen shot is US Airnet aviation forecast, it gives a 3 day forecast easier to figure {orange burg Sc]


Ps just re-read your post & noticed the time of 6.30 ish........ well, there ya go!

Thank you so much! Actually I feel much better now. I just didn't realize I had all this information at my disposal. I'll pay more attention to the chart before I paint anything.
 
A couple things about clear--which I'm moving away from---I tend to lay clear over wet or tacky paint-takes care of the wrinkle problem and there's no waiting days with the chance it could happen anyway !! One other thing, if it fogs, ---I let it tack off and go right back over it again --most of the time--99%--the fog is gone and no ill effects.

It's already been a day or two. Should I try a couple coats and wet it again? Or should I just wet sand it with some 800 or 1000. The finish is pretty smooth so I think I could get away with a 1000
 
I recently had the dreaded wrinkle issue with Duplic-color Acrylic Enamel. Others on the form suggested it was caused by off-gassing of the previous layers due to laying down my clear too soon (4 days) after my last coat. So as other posters on this thread suggested enamel, especially acrylic based enamel needs time between coats. I called their support and the recommended time to cure is 7 days. So although the symptoms are not the same waiting between coats is key using these paints. I have had cloudy clear but with Rustoleum only and I am pretty sure in my case it was due to humidity.

I know have the following protocol, paint 2 light layers, 1 medium, let dry 3 hours before handling it, leave for 2 days, wet sand 400 - 600 depending on the coats, clean and leave for the balance of 7 days min, then repeat. So far using this protocol I have not had any issues, although I need to invest in a temp humidity gauge as right now it's by feel.

Realistically although I am now getting good results waiting a week between coats, touch ups, etc. it is not a very efficient system. So I just picked up a compressor to go with the gravity fed spray gun I picked up a while back but have been to chicken to get into. My plan is to get some comfort with the Duplic-color 123 system, which is lacquer based and apparently you can paint, clear, do whatever with minimal times between coats, re-coats, etc.

By far there is much to learn when it comes to getting good results with finishing!

I like Duplicolor and Rustoleum, but as mentioned didn't realize how much the dew points can seriously affect the outcome of a paint job. I'll have to try the lacquer paint system sometime.
 
I've used enamel in non-rocket applications for ages, and recently picked up lacquer paints due to extensive forum searching... and I don't think I'll ever go back, unless limited by a specific color availability. It's dry-to-sand in a fractional hour rather than multiple days.
 
I've used enamel in non-rocket applications for ages, and recently picked up lacquer paints due to extensive forum searching... and I don't think I'll ever go back, unless limited by a specific color availability. It's dry-to-sand in a fractional hour rather than multiple days.

Do you get them in cans, or do you have to mix them and use a spray gun/airbrush? Always seemed to me the color selection is much more limited in the lacquer, then again I have to admit I haven't put a lot of effort into shopping around for them..
 
Last edited:
It's already been a day or two. Should I try a couple coats and wet it again? Or should I just wet sand it with some 800 or 1000. The finish is pretty smooth so I think I could get away with a 1000

I used to do the same thing, and with color I think you're fine. However, Metallic paint (silver) will rinkle in a heartbeat if it is not fully cured. I tried it a second time about a week ago, and a few spots wrinkled on a Minnie Magg - humidity at the time I painted - 26% at 70 or so degrees, which pretty much prime weather for painting..

I really don't use clear at all any more, but I wanted top smooth out the silver and sort of seal it up before I put vinyl on it. Oh well.....sand...paint...sand...paint.....
 
I used to do the same thing, and with color I think you're fine. However, Metallic paint (silver) will rinkle in a heartbeat if it is not fully cured. I tried it a second time about a week ago, and a few spots wrinkled on a Minnie Magg - humidity at the time I painted - 26% at 70 or so degrees, which pretty much prime weather for painting..

I really don't use clear at all any more, but I wanted top smooth out the silver and sort of seal it up before I put vinyl on it. Oh well.....sand...paint...sand...paint.....

Yep that's for sure
 
Often overlooked is the "dew point". Depending on the temp....humidty.....time of day<the dew point varies.

if it is 7-8 degrees or less do NOT paint. your finish will blush.

To expound with out getting technical. Out side temp is 78.......dewpoint is 72 78-72=6 do not paint.

AS eveniing approaches the dew point temp gets closer to the temp. Early morn till 9-10 also. The problem is exacerbated in spring & fall when ground temps interacting will air temp are changing. Fronts passing through also
The only way to tell is check your weather. There are other causes... but this ones a biggie often overlooked.


See the screen shot below for S Cali...below....it's easy to find. Right now it should be close to 3.00 out there and as the day progress's it's going to get worse. Obviously the humidity [for painting[ is much worse than you thought. [71% now] you don't feel it but it's there. All the new paints don't have the same quick dry solvents they used to & the aerosol mist pulls the moisture out of the air onto the surface, where it gets trapped, can't escape and ruins the finish. The result is like white/grey water marks on fine furniture, when you don't use a coaster. [result not the process] If you wipe up the water right away, furniture won't mare...if the moisture could escape from surface of rocket it would be fine.... but the newer paints take so long to cure it's trapped.
I want a 15-20 spread just to be safe. I find it best to paint outside between 11-3.

I have rattle-canned rockets outside in 40 degree temps when there was 10-15% humidity and got away with it.

Google it for the complex definition

Ps I did this for 28 yrs commercial painting. Most outside.

Right now in San Diego the outside temp is 66.... dew point is 57. 66-57=9 For me No painting anything gloss

Other screen shot is US Airnet aviation forecast, it gives a 3 day forecast easier to figure {orange burg Sc]


Ps just re-read your post & noticed the time of 6.30 ish........ well, there ya go!


That's really interesting...Never thought of that either !
 
Do you get them in cans, or do you have to mix them and use a spray gun/airbrush? Always seemed to me the color selection is much more limited in the lacquer, then again I have to admit I haven't put a lot of effort into shopping around for them..
All out of rattlecans. I get duplicolor mostly from the auto store, occasionally hobby Testors rattlecan.
 
Because this thread inspired this, I thought I would post my latest tool. This is an inexpensive temp humidity gauge I picked up and have it hanging on my spray booth. I also added some labels with the recommended ranges for painting, just because my memory is so bad. Another nice feature is the min-max memory, which will help to know if the environment popped into the "do not paint" zone.

View attachment 175086
 
Taking Crazy Jim's advice I repainted my fins on my SUMO and they turned out much better knowing what the temp and dew points are definitely helps. Thanks CJ!! Keep in mind I haven't had a lot of time to work on this and this weekend was first free time I've had in awhile. The masking tape has been on the rocket since June and when you are painting multiple color schemes sometimes you have no choice, but it explains why the paint pulled up in some areas.

As you can see the tape left some noticeable ridges, which I plan on carefully wet sanding them down. Certain areas of the red have been wet sanded because I had to remove a few imperfections. The rest of the rocket I was planning on painting gloss black. I figure if the yellow paint line on the primer gets "lost" I can always mask the pattern and come back and paint over black and you won't notice anything. Not that it matters because it will probably get banged up after the first few flights. but I always try to laid down something cool.

2014-07-05 15.14.08.jpg2014-07-05 15.14.20.jpg2014-07-05 15.14.46.jpg2014-07-05 15.15.04.jpg2014-07-05 15.15.13.jpg2014-07-05 15.15.25.jpg2014-07-05 15.16.11.jpg2014-07-05 15.17.20.jpg2014-07-05 15.17.34.jpg

I haven't really decided on a final scheme, but might throw in some Black and Orange? I'm considering extending the color scheme down into the AFT section of the airframe where it is currently white. As far as retention I was going to go with AP retainer, but ordered a MADCOW retainer plate instead. I think it will look better having the plate. I like the AP retainers, but I should of added a 4th center ring to give the retainer something to butt flush against. I just think it looks cleaner.

So any suggestions on paint scheme or wet sanding feel free to comment.

Thanks!!
 
Back
Top