clearcoat cratered

[nooshie]

I'm new at this so I'm sure this problem is something of my own doing. I am going to flame a lawn mower for a friend. Somfething for me to practice on, anyway I sanded and primed with PPG-K-36 mixed with K-201. After a day I painted a burgandy urethane with DX-61 hardener and 602 reducer. The paint job looked great but after 24Hrs it was still tacky so I waited another 24 hrs and it seems to bef dry. I put clearcote DU-75 mixed with DX-80 hardener. I cleaned athe hood with DX-330 cleaner and put on the clear. The clear cratered and it showed where I had wiped with cleaner before shooting. I have wet sanded and put it back in primer. Is it possible that I didn't get enough hardener in my paint and it was still not cured even after 48hrs?
Any comments on this will be well taken.

Nooshie

 

[John Pierce]

Did you wipe off the cleaner with a dry rag after cleaning the hood? The cleaner itself can cause craters if you don't wipe it off dry and use a tack rag to collect dust particles right before shooting.

Other culprits would include: 1) water in your line 2) contamination of some sort in your gun 3) not wiping off some form of grease even though you used the cleaner

Good luck,
JP

 

[nooshie]

John, Thanks for the reply. I will definately check the items you mention before I shoot the clear again. I'll post the results in a couple of days.

Nooshie

 

[tcannon]

Don't use one of those "sticky" tack rags. Like the one's at the hardware store. I used them years ago and you have to be carefull not to press too hard or it'll leave a residue. Get some of the Dupont Blue Sontara wipes. Your jobber may refer to these as finish or base coat wipes. These will clean off surface debris without leaving anything behind. TC

 

[rex]

What paint was the burgundy?The DX61 is the hardner for Concept color and clears but that 602 don't sound right.I think that was the reducer line for acrylic enamel (Delstar).Sounds like one of these weren't the right product and if it is the hardner that's why it stayed soft,and could be the prob with the craters.By the sounds of it though there was contamination on it and you didn't get it all off,leaving the streaks.It might be a reaction between the 80 hardner and the 61 if it was the wrong one.

 

[nooshie]

Rex, The burgandy is not a concept color, so this probably the problem. I have sealed it an re-coated with burgandy mixed with DT-870 and DX-61. 48hrs later it is still soft. I'm learning a lesson here about mixing products. I hope with time it will get hard enough to clear. Can I use wet look hardener with urethane clear?

Thanks for the imput. Some things I just seem to learn the hard way.

Nooshie

 

[rex]

Sounds like it's a hardner problem.Since the paint isn't designed for the 61 hardner it'll probably never cure but it will eventually dry.I'm not familliar with the hardner you mentioned so it's hard to say if it'll work or not.The best thing to use is the hardner made for the clear.Generic or aftermarket hardners worked well in the old enamels but I don't trust them in urethanes,mainly because mix ratios vary from one brand to the next so the chemical makeup of the hardners are different.As an example PPGs Concept clears mix 4-1 and are reduced,but their cheaper Omni line mixes 2-1 and the hardner contains some reducer.Mixing them up could be suicide as you're finding out.

 

[nooshie]

Rex, You're a smart guy. I think I have caused this problem and I'm glad it's only a lawn mower hood. I did paint a spot on the underside that I will clear first. If there are problems I will have to think of something else. The guy I am doing this for is a good friend of mine. He builds HD's and restores corvettes here in the Ellensburg, WA. He gave me this project to give me practice. This is a farming community, ( guess what I do for a living), I really do appreciate your help. Learning how to do this thing is really important to me.

Nooshie

 

[Jim]

nooshie,Find a paint line like Dupont,PPG,HOK or whatever and get thier "Tech Sheets"They're worth thier weight in gold.Follow them like the Bible,The only thing you'll have to worry about is how to hold the spraygun.Find a system (paint line) and stick to useing thier products,you'll have alot less headaches.There are some tech sheets for Dupont and HOK in the "Links" section of this flames board.I guess PPG took thiers off.Good Luck!

 

[rex]

Just remember a few things.Mixing products can get you in trouble,and usually a paint line will keep the labels and colors of them similar.Although I'm in Florida I'm surrounded by oranges and livestock and grew up in a similar setting so I know what's sitting around on the shelves.If you have any doubt about a certain ingredient stop by or call the paint store,they should clear things up.Hang out and read here,if you dig back in older posts there's alot of info to be had.You learn by mistakes and we all did it,it won't come overnight but hanging here speeds up the learning curve

 

[nooshie]

I have to tell you all, Thanks for the support. I still think I can do this thing. I need to not rush the job and research each step before I do it. I found the web site for ppg. It is: ( ppg.com/cr-refinish/phase1/frmHome.asp). This site has all of the teck sheets on line. Just click on product information. I will learn to read first, and remember something I heard when I was a kid," You can always sell a good job late, but you will never sell a bad job".

Nooshie

 

[Jim]

Nooshie,thanks for the PPG link.I'm gonna copy thier tech sheets in case they remove them from thier site too.It's nice to have a copy until you get used to mixing and the whole process from whatever paint line you choose.I like HOK cause it seems pretty easy and I remember the ratios for simple base coat/clear coat.I only wish they had a bigger window to apply the clear.Don't worry about mistakes,It's "the learning curve"Everyone here has been thru it!Just don't try to "alter"the tech sheets until you know what you can get away with.Jim

 

[tcannon]

I've found my local PPG jobber to be helpfull in printing me any of the PPG/OMNI data sheets. TC