Good thing I tested these paints

[Buckeye]

Shown is the progression of primer>paint>clear I applied to a scrap piece of fiberglass airframe. All directions were followed and wait times observed.

All was good until I applied the clear. Within seconds of a light second coat of the clear, the wrinkles formed. This is my first experience with clear coat. Thoughts?

I quickly moved from inside the house to sunny 50 deg F outdoor temp to do the clear coat. So, I don't think temperature was a big issue.



Aside: I tried a Duplicolor product for the first time to see what all the fuss was about. Meh. The min temperature requirement is more stringent at 60 deg F vs. 50 or 55. The application process for this filler is tedious : 10 min, 10 min, 10 min between coats. It easily rubbed off while applying Bondo to fill some pits. The spray nozzle messily painted my finger, and is the type that requires to spray upside down to clean. I like the Rusto filler primer better.

 

[G_T]

How many coats of what, at what time intervals, did you do? What was the temperature and humidity like when you did it and when it sat around drying?

You had too much paint buildup that was not dry enough for the clear coat. The clear coat went on, flashed off, and shrunk... rippling the surface.

With clear coat, I like to do a mist coat or two and let them get decently towards dry but not really dry, then do a wet coat to level it out. Without, of course, using so much as to result in runs.

Also, check the compatibility of your primer with your test body tube, and check how you prep that tube. How did you prepare and clean it before starting with the primer? What did you use to clean with? Did you make sure not to touch the surface with your hands or anything containing even micro traces of oil?

For fiberglass such as that, a good sequence might be to clean first with detergent and water and let dry thoroughly. Then surface sand with perhaps 400 grit to a matt finish. Then wipe off with paper towels. Then wipe off with acetone. Let the acetone dry, then wipe off with denatured alcohol. Let that dry, and have at it with the primer. Mist coats of course.

If you didn't do any prep on the fiberglass scrap, it may have had traces of mold release and oil on it. That's not good for most paint!

The times recommended for re-spray are not fixed just general guidance. They should be about right for something around 80F or a little warmer, on a day that is not humid. Lower the temperature, and/or raise the humidity, and those times become insufficient.

Gerald

PS - I'm NOT an expert on painting.

 

[manixFan]

What was your time interval from paint to clear? While the color Krylon says you can recoat in 24 hours, the clear says to wait 48 hours. (I'm not talking about multiple coats within the recoat window). I've found I've had to wait a week with a lot of paints for them to fully cure before covering with clear.

And, from the instructions:

"Best results when temperatures are 55° F to 75°F and humidity is below 60%. Applying outside this range may impact finish."

So you painted outside the recommended temperature range. You might not think that the temp was an issue, but the results seem to speak otherwise if you followed all the other instructions. What really matters is the air temp that the spray encounters. As the paint solvent starts to evaporate when it hits the air, it cools the paint even further, which can cause moisture to condense out of the air and be deposited along with the paint. It can also affect how the paint adheres to the surface since it's now much colder than the recommended range.

I've never had good luck painting below 60º with any kind of spray paint, and generally I try and stay above 70º with a dew point in the 50's. I've found if the dew point is within 10º of the air temp I'm much more likely to have problems with moisture in the paint, and if it's in the 60s, I've learned to just wait for another day.

Based on the wrinkles, I'd say it was too short of a cure time/too thick, but it's also hard to rule out the temp.

Tony

Here's a typical explanation of wrinkling:

"A few different factors can cause the finish to wrinkle or crack when applying another coat of paint.

The most common – is applying the paint too thickly – which makes the surface of the paint dry too fast and not the underside. When you re-coat, the solvents in the paint shrink and this causes the wrinkling.

How to fix spray paint crackle and the way to avoid it– spray only when the temperature is 65 – 85 degrees, apply only light even coats, and re-coat every few minutes.

Also read the back of the can. Some brands say you should get all re-coating done in under 30 – 60 minutes. After that, do not re-coat at least for 24 – 48 hours or the paint may wrinkle. Again…read the label for specifics."

"High Humidity. Uncured paint that is exposed to high humidity, dew or rain can wrinkle.
High Heat. Temperature extremes can also cause wrinkles.
Too Thick of a Coating. Applying too thick of a coating of paint is just one reason paint wrinkles. What happens is that the surface of the paint dries, but what is under the skinned outer layer is still wet. With the uncured paint trapped under the skin, the dried film has nothing to anchor to. As the dried layer expands and contracts it develops a web of wrinkles."

 

[Hobie1dog]

i recently returned my Duplicolor Metalcast paint as all it did was run everywhere, it's as if they cut the solids down to 10% and the rest is solvent. Home Improvement cheap paints are getting to be more disappointing. I'm returning my Krylon paint this week, same thing, nothing but runs.

 

[manixFan]

i recently returned my Duplicolor Metalcast paint as all it did was run everywhere, it's as if they cut the solids down to 10% and the rest is solvent. Home Improvement cheap paints are getting to be more disappointing. I'm returning my Krylon paint this week, same thing, nothing but runs.

I’ve had good results with the Metalcast paints, but they are more challenging than regular paint. You have to use the special base coat, and because the top coat is transparent, it is thin. It took a fair number of very thin, light coats to get the right results. But it’s very nice looking once completed. Because of the cost, I’ve only used it on small diameter rockets, 54mm being the largest.

So at least in my experience, the results were worth it. Unfortunately the last rocket I painted with it succumbed to a bad liner in an Aerotech 1103X.

However, I too have that paints I’ve purchased lately seem a lot more prone to running than those I’ve used in the past. I tried Rusto for the first time in a long time and had a fair amount of trouble with it. Same with the new Krylon. I know they’ve changed the formulas and so far it’s taking a while to get the hang of the different characteristics.

Tony

edit: added paragraph on new paints

 

[ep29030]

@manixFan: ditto on the metalcast paints. You have to use their basecoat, and they colors are intentionally thin, so you see the metallic basecoat to give you that appearance of depth--just like the old candy apple paints of years ago. Gives a beautiful appearance.

I also agree on the clearcoat about doing 2-3 light mist coats before a thicker coat. I found that my clearcoat problems cleared up with light coats first. Have had good success with the DupliColor clear coat as well. As to paint running on your fingers, buy one of the triggers ($5-8) that snaps down on the paint can and that problem is gone. Plus, you get better control over the trigger and the can.

 

[Buckeye]

It was about 72 hours from paint to clear. I didn't think my paint nor clear coats were excessively thick.

Nonetheless, next time I will be careful about surface prep and air temperature, and wait a good long time before applying clear coats over paint.

 

[ep29030]

It was about 72 hours from paint to clear. I didn't think my paint nor clear coats were excessively thick.

Nonetheless, next time I will be careful about surface prep and air temperature, and wait a good long time before applying clear coats over paint.

Good point about waiting before moving to another coat--some paints have wait times of 4-7 days before anything new can be applied. This is one advantage of the lacquer paints--wait times can be in minutes to a day at most.

 

[Orien]

I’ve had good results with the Metalcast paints, but they are more challenging than regular paint. You have to use the special base coat, and because the top coat is transparent, it is thin. It took a fair number of very thin, light coats to get the right results. But it’s very nice looking once completed. Because of the cost, I’ve only used it on small diameter rockets, 54mm being the largest.

So at least in my experience, the results were worth it. Unfortunately the last rocket I painted with it succumbed to a bad liner in an Aerotech 1103X.

However, I too have that paints I’ve purchased lately seem a lot more prone to running than those I’ve used in the past. I tried Rusto for the first time in a long time and had a fair amount of trouble with it. Same with the new Krylon. I know they’ve changed the formulas and so far it’s taking a while to get the hang of the different characteristics.

Tony

edit: added paragraph on new paints

Just put the last coat of the Anodized Red over the base coat this morning. Gorgeous!