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JamesShort · **Posted:** Tue Jun 22, 2010 5:24 pm

I need help with spray painting. I've wire brushed and sanded the rust of my donor struts for the Koni's (on the parts that are still well painted, I just lightly sanded to scuff it up). Cleaned it off with simple green and water and let dry. And lightly sprayed them with a coat of gray Rustoleum Primer. It's been 18 hours and they are still tacky and un-sandable (as in the paint will just smear).

Does primer take a long time to dry to be sandable? What is the deal with saying "Apply another coat within 1 hour or after 48 hours" ? They are hanging in my garage....probably 80 degF and 50% humidity.

Any general spray painting help would be appreciated.

steve remchak · **Posted:** Tue Jun 22, 2010 6:02 pm

you might have done better to use a self-etching primer.

plus i wonder about the simple green and water application; possible residue?

primer should surely be dry to the touch within a few hours at most.

JamesShort · **Posted:** Tue Jun 22, 2010 6:27 pm

Maybe I mispoke. It is dry to touch..but if I pick it up and put pressure on the surface with my fingers, there is a slight resistance to pull my fingers away.

I thought self etching primer requires that the object be completely bare metal? These struts are from a 2008 car so they are say 98% clean and painted, and a few edges were a tad rusty and where the spring touches the spring perch.

Figures you'd be the first to reply to this thread

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steve remchak · **Posted:** Tue Jun 22, 2010 6:42 pm

JamesShort wrote:

Maybe I mispoke. It is dry to touch..but if I pick it up and put pressure on the surface with my fingers, there is a slight resistance to pull my fingers away.

I thought self etching primer requires that the object be completely bare metal? These struts are from a 2008 car so they are say 98% clean and painted, and a few edges were a tad rusty and where the spring touches the spring perch.

Figures you'd be the first to reply to this thread

.

i'm a spray paintin mutha, if it sits too long i'm sprayin it. :lol:

tacky after 18 hours is odd. bring them into the house for a few hours. i can't swear to self-etching primer on a painted surface but if you roughed it up it should bond i would think.

sounds to me like you have some reactivity issue going on between the new paint and the existing paint.

Jason Mauldin · **Posted:** Tue Jun 22, 2010 7:01 pm

I would suggest hanging them over a heat source for a while, but you might screw up the oil inside.

Michael Westerfield · **Posted:** Tue Jun 22, 2010 7:04 pm

Jason Mauldin wrote:

I would suggest hanging them over a heat source for a while, but you might screw up the oil inside.

I was going to say are you sure the oil on the outside wasn't messing with the paint?

JamesShort · **Posted:** Tue Jun 22, 2010 7:19 pm

Oil on the inside? That stuff is long gone

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I'm just going to give it another day....see how it goes. Sand it and primer it again. Maybe primer will like to body to primer and dry quicker.

Jason Mauldin · **Posted:** Tue Jun 22, 2010 7:37 pm

Stick them in the oven for a little while. Not too hot.

Steven Carter · **Posted:** Tue Jun 22, 2010 11:42 pm

Possibly useless anecdote follows:

I used POR15 products when prepping/painting the suspension parts for the Z restoration, and after three years have had very good luck with them. Removal of all prior paint and grinding off surface rust is key--sounds like you've got that covered. I then sprayed phosphoric acid on the metal (Metal Ready) which converted remnant rust to iron phosphate as well as etched the unrusted surface metal, then rinsed and dried using a heatgun. This was followed by POR 15 then their primer coat. After two primer coats (sanding in between) the finish coat (Chassiscoat black) was applied. No rust, chipping or flaking at all after 3 years.

I only mention the above because the POR15 product is a nonporous "rust inhibitor" similar to what Eastwood and othe places sell. With only the porous primer coat, the part is left at risk for rusting through the primer even after topcoating it. May not be a concern, but thought I'd offer up some unsolicited advice given the care your taking with all the kewl yellow paint and whatnot...

In my experience, weather and coat thickness play the biggest part in drying times. Unless your garage is climate-controlled 50% humidity is probably on the low side of the estimate given the current heatwave--more like 75% or better. Take it inside, wait a couple days then check it.

$0.02

edit: misread the OP...If you didn't get rid of the original powdercoating/pain, light scuffing may not be enough to bond it. You may have to strip the paint. Reactivity is also a good point to bring up as well. My method is probably a bit of overkill, but the end result was worthwhile.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Couple of comments and ideas...

- I really never use primer any more unless I'm painting something that's bare metal and I actually care about what it looks like (like a rollbar). For a strut, don't bother. If the surface is clean, good paint will stick fine. In fact I would not primer anything that already has paint ... I don't think primer likes anything but bare metal (but I'm not an expert)
- I stay away from Rustoleum whenever I can cause their normal enamel products take so DAMN long to dry. Could be the same with primer
- My favorite stuff these days to paint random stuff is the engine enamel from Autozone. Fast drying. Hell anything is fast compared to Rust-O. Engine enamel seems to be a lot more durable than the also-fast-drying Krylon. Krylon actually dries too fast for my tastes and tends to show more drying "features". Rust-O definitely makes a nice shine since it will flow for a while, but at the cost of lots of waiting for drying (unless you have an oven....)
- When I *have* to use rustoleum I usually do a 30 minute bake at 200F in the garage oven. Yes I have an oven in the garage.
- Use Acetone to clean anything before painting it. Acetone is hygroscopic so it will pull any remaining water off the surface. SG usually leaves an organic film

Mike, painter of lots of car bits, but not anal retentive about results

Vincent Keene · **Posted:** Wed Jun 23, 2010 8:19 am

MikeWhitney wrote:

My favorite stuff these days to paint random stuff is the engine enamel from Autozone. Fast drying.

Ditto. The Dupli-color engine enamel works very well IMO. If you are starting with bare metal use Dupli-color self-etching primer (wear a mask!) and then use the engine enamel. It produces a shiny and hard finish.

WalterHouston · **Posted:** Wed Jun 23, 2010 8:55 am

I like the POR 15 type products for certain parts, but they may be overkill for struts. Self etching primer is only for clean, dry, bare metal.
I only use primer when I have sanded down to bare metal or old primer. I haven't had good luck with primer over top coats.
The baking idea might work, but there are several possible causes of your problem. I hate to say this, but I think you need to start over with your project. If it were me, I'd remove all the paint I could and then use a fast drying engine enamel.

JamesShort · **Posted:** Wed Jun 23, 2010 9:12 am

Well it seems pretty dry this morning. Also the primer says its for previously painted and/or 'sound' rusty surfaces. My final coat will be Duplicolor enamel (school bus yellow is very close to Koni yellow):

Does anyone have a sandblaster? Maybe I have to get myself together and go teach a few classes at TechShop so I can use their sandblaster

.

JamesShort · **Posted:** Wed Jun 23, 2010 9:34 am

What would you guys use to strip it quickly and does a good job. I'm not sure if they come painted or powder coated from the factory.

Jason Mauldin · **Posted:** Wed Jun 23, 2010 9:37 am

Unless the factory paint is in bad shape, I wouldn't strip it off. I don't think you're going to duplicate the quality of that paint very easily. Scratch up that paint a little and spray over it with Engine Enamel.

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