my paint failure. I can't let this happen again

[gazmosis[501st]]

I have painted several sets of armor and many helmets. Sometimes all goes perfect. Other times, not so much. You want to learn from your failures but when I did something that succeeded before but failed now...what is there to learn? I posted earlier about using a type of goo gone to get off some adhesive left behind by the tape used in the fitting process of my armor pieces. After all was wiped off, The armor looked really clean and I asked if anyone had used this as a degreaser/cleaner in their prep because I know that any oils that are left on the armor due to inevitable overhandling can harm paint adhesion. There was concern in a couple of responses saying it would be best to stay with old school sanding as a prep. The sanding just was not taking off the adhesive. I used the goo gone to take the adhesive off only where necessary. I then used 400 grit to clean the rest of the armor pieces under running water. Someone had posted in that they used a lava type soap...even dish soap was used. I used dish soap before and had a failure so I avoided it. I opted for orange glo. A mild abrasive with no film and a top notch degreaser for oil removal. I sanded/cleaned the snot out of each piece. Metuculously. I primed with rustolium plastic primer. Let that set for 1 1/2 days. Then painted this morning. A light first coat with rust. professional. It lifted off almost immediatly. In no particular pattern. Some in more areas than others...more on some parts than others.

Now let's find out what I did wrong. I am painting in my basement with a constant 65 degree temp and low humidity. I can't imagine that I left ANY of the cleaners on with the amount of sanding/rinsing I did. I didn't wipe off any parts so no secondary transfer could come from a rag. I compressor blew the main water off then let air dry for 24 hours. The since the paint lifted the primer, the only conclusion I can come to is that 400 grit is not course enough to use for paint prep and the armor surface was too smooth for the paint to bite to it. I always thought that since the primer was for plastic, there was something in the primer that bit into the plastic for you. Am I wrong here?

Lastly, any spray painting needs to be applied with all coats about 15 min apart. Does this go for the primer as well? For example...apply primer, wait 15 min. then top coat, wait 15 min then more top coat ect....? Sorry this got so long. I am really frustrated right now and I am a perfectionist so that is NOT helping.

Where did I go wrong?

[jnnfr72[TK]]

Dang, that stinks. Mike from Trooperbay does alot of painting.... Maybe he will chime in.

Did you get ahold of a crappy can of paint? Might be a combo of sandpaper / no-good paint?

[xaoslord]

I've had bad cans of primer before. It would seem to spray ok, but once dried, it would fuzz out and brush off as if there was nothing to make it stick.

[pandatrooper[TK]]

I have used goo gone to remove adhesive, and it's fine if you wash it afterwards with detergent and water. Personally, I have never had problems with dish detergent. It's a good degreaser (removes film and finger prints) and any traces of oil. You have to be careful with other degreasers as sometimes they are oil based. This is the process I always use:

 

- spray in a warm / dry environment

- low humidity is best

- non windy

- out of direct sunlight (shade is best)

- in a clean non dusty area, no grass / dirt etc.

 

- sand the plastic (this creates tooth for the primer to bite) using a scotchbrite light pad

- wash everything with dish detergent, rinse and let dry

- do not dry with a towel or compressed air as both will attract lint

- use a tack cloth to wipe the armor before painting to remove any stray lint

- make sure the paint is room temperature

- shake the paint well

- I tend to use Krylon or Rustoleum (the "plastic for paint" stuff like Fusion is marketing BS and sticks no better to raw plastic than regular paint)

- stick with the same primer and paint brand (do not mix brands and do not mix enamel over or under lacquer)

 

- Prime the armor first (use white primer if you do not want to use grey)

- I do 3 light coats (as an indication, the first coat should not be opaque. Only after the 2nd or 3rd coat should the white be covered)

- wait 10-15 mins between each coat

- I would wait overnight before top coating

- apply a light coat of white (again, it will not be opaque, don't try to lay a heavy coat on, the first coat should be light)

- leave 10-15 mins between each coat

- do at least 4 coats

 

Let everything dry for 5 days before applying decals, or hand painting any details. This will ensure everything cures through.

 

I am guessing you maybe laid the primer on too thick and it did not cure through / bond with the plastic or the prep wasn't thorough enough. The paint bonded to the primer, then it flaked off. Also, 400 grit is actually a bit too aggressive, I would have used 600 (black sandpaper not wood type) or better yet a scotchbrite pad. You actually want a finer tooth than a rough tooth for paint on plastic.

[gazmosis[501st]]

Thanks soooooo much for the thorough response, Terry. I believe my issue is with the primer. # I probably put it on too thick ergo the slight run I had on one part and #2 I think I need to let let the primer cure a little longer 3-4 days maybe just be sure. I was fairly meticulous about my cleaning of the parts. I still need to strip a couple parts before re-trying this. Have you ever wiped things down with thinner or alcohol (suggested by ATA himself)? I will let the primer cure a couple days before painting. I think this will be my ticket.

Thanks again!!!!!!

[kevster[TK]]

If you use alcohol, I would still rinse it with water. I've never heard of what happened to you though, thats crazy! It just peeled right off the armor.... When I painted my armor, it was too warm outside so I did it in the spare bedroom one piece at a time and would open up the window so it was usually about 80 degrees. With it being kinda cool in your basement, if you did put it on a little thick then ya it probably didn't cure all the way sitting in your basement. Since i was only doing about one piece at a time, i wrote down when my pieces were primed and painted. I don't think any of my pieces were painted less than 4 days after priming so they had plenty of time to dry. Then it was about a week and a half after painting before i touched them after they were painted. Even with all that it still didn't come out perfect. There were very few spots where the paint had dried completely flat, so i went back and wet sanded the whole suit to make it nice and smooth. Just saying, painting is easy in a way, but still an absolutely a pain! haha I'm sure you'll do fine on the next go though.

[gazmosis[501st]]

It's not like it totally peeled off but it lifted in certain areas enough that with any more coats of gloss it was going to be awful. Time is the key here I now know. Time and patience. I should see this as a blessing. I am building these parts so that I can apply for centurion. I need to get those side gaps down 1/2 inch, though. This will give me the time to work on that.

I wish that a few dull areas were my only issue. I love the polishing process and bringing out the glossy beauty in the armor.

[stormtrooperguy[501st]]

I think time is definitely the key. If you look at the cans, they usually say something like "recoat within 1 hour or after 24".

 

Things usually work for me because I go REALLY fast. For example: I just painted a new Rex helmet. I put the white coat on, waited 45 minutes, masked it off with super-low-tack painter's tape. Painted the blue parts, waited about 20 minutes. Took the masking tape off and started weathering. The paint is so soft at that point that I can scratch it with a finger nail, but it works.

 

Going at that speed, I tend to be able to mix brands, layer colors and all sorts of wacky things. But, if you let the base coat sit for 3 hours then try to do the blue, the base will orange peel.

 

So I think you either need to go REALLY fast or take it slow.

[pandatrooper[TK]]

Agreed, timing is key for top coating. Follow the instructions for timing, temperature and humidity.

 

Personally, I don't use alcohol for anything other than cleaner paint residue that's rubbed off a blaster onto my thigh armor, or removing pencil marks from trimming. Alcohol leaves a residue or does something to the plastic to F*%$ the surface up, and paint does not bond well afterwards. Always wash with dish detergent (remember, that stuff was created to remove grease and fingerprints from dishes without leaving a residue) rinse and dry.

 

My brother was a professional autobody painter for many years, and painted many cars, bikes etc. so I learned all the finishing tips from him.

[gazmosis[501st]]

Thanks for the input, Terry! I have wiped down all of my previous projects with alcohol and ahe only paroblems that I have had have been with primer application as I now look back on it. The same thing happened in this case. Primer was too heavy and I painted too soon. I was able to strip all the parts down successfully and (although you would disagree) I did wipe them down with 91% alcohol. I primed with three superfine mist coats.After three, they were covered well. The parts were then moved to my warmer upstairs and will bve left to cure for 72 hours before topcoating. I hope that on Tuesday I can post with news of my pristine paintjob.

I did not get impatient. I did wait a total of 72 hours for the primer to cure. The temp is supposed to drop here in Chicagoland and it will rain for the next two days. Humidity is a no-no!!! I painted today and the result is every troopers dream!! What a finish!! After two weeks I can polish out a few inevitable lint specs that no one but me will notice, but overall I could not expect better. Thanks to all who helped and gave me their suggestion for success.

Edited November 7, 2011 by gazmosis