? Spraying Rustoleum in cold weather,,, how long to harden

[fishrdan]

I'm ready to spray my transom assembly and outdrive with Rustoleum, but wondering how long I'm going to need to wait before coats. When I've shot Rustoleum before it was over 100*, but it's going to be in the 50's for the next week so I imagine the re-coat times are going to be a lot longer. I'm thinking a tack coat in the morning, let it sit far a few hours and shoot it again, then spray it again the next 2 days. I'm will be shooting it from a cup gun and looking to apply 3 coats.

From your experience in cool weather like this, should I be spraying a coat each day? Or just wait a few hours, IE: shoot it at 8am, 12pm and 4pm?

Also, how long is it going to take for the Rustoleum to out-gas and harden in this cool weather? From my past experience; in hot weather it was 2-4 weeks before you couldn't dig a finger nail into it, which is going to be important for me since I'm going to be torquing the parts down.

Is there a hardener or anything I can add to the paint to accelerate the drying time?

I plan to make a "hot box" to keep the parts in while they are drying, cardboard appliance box with a electric oil heater inside. Try to keep it at 90* or so while the paint cures.

(Oh yeah, guess I should mention the parts are off the boat, so I need to wait until they are completely dry before installation.)

Thanks!

 

[kaferhaus]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

At 50 the rustoleum will still "flash" in about 20-25 minutes. However rustoleum actually cures very slowly even in moderate temps. I usually wait several days before I do any serious handling.

At temps under 70 I thin with about 5% naptha down around 50 I use 10%.

I recoat within an hour, no matter the temp. Use thin coats, it flashes quicker and will end up curing quicker even though you apply several coats.

Although I must admit I don't really care for rustoleum on boat hulls.... I like the two part urethane's much better. Not as forgiving, need a respirator and much more expensive. But done right a much better product and appearance.

They're also about 5 times as resistant to "trailer rub" as rustoleum is.

But rustoleum is a quick and cheap touch up when you do rub through it.

 

[kabcpapc]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

Maybe you can try Valspar Enamel Hardener available at Tractor Supply for 12.99 for an 8 oz. can. Will definately speed up the dry time. It's got some of those isocyanate compounds so use a good respirator that can be used with isocyanate paints. A lot of respirators specifically say don't use with isocyanate paints.

 

[kaferhaus]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

The enamel hardener would "help" but you have to be very careful using it. Just a little too much and the paint will "craze" the first time you bump into something.

Also the stuff mentioned is very dangerous stuff. I have a external supply type respirator... exhaled air goes out the valve but inhaled air comes from and is filtered outside of the shop...

You're obviously on a budget or you wouldn't be considering rustoleum in the first place... but a good marine hull paint or even a decent automotive enamel would be the best course of action.

But if it's just a beater fishing boat, I'd use what you're planning too... the best compromise between cheap and decent which is the rustoleum.

 

[fishrdan]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

kab,

No tractor supplies local here, but I'll see if I can find the hardener if I go with the Rustoleum.

kaferhaus,

So assume I want to go with a better paint, automotive acrylic enamel, urethane, etc. What would be a good quality, easy to use, and fairly inexpensive paint to use. Say, $25/qt and not the nasty stuff as I only a run of the mill $40 3M respirator (organic cartridges I think?). I've never sprayed automotive or 2 part paint before, but have done a lot of wood finishing. I'm guessing I'll need 2 quarts for the transom assembly and outdrive. The hull is an 01 Crestliner and I need to do some touch-ups to the hull and trailer, PPG is what Crestliner uses, so I'm heading down to the auto paint supply store to get a few quarts of paint anyway...

I was going with the Rustoleum since I have 3/4 gallon of black, it's easy to touch-up and should look good for 4-5 years,,, around the time I'll need to do a major service on the outdrive and re-shoot it.

 

[kaferhaus]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

For hull paint I'd use an automotive paint. PPG is good paint and I've used a lot of it.

for the outdrive I think rustoleum is fine. It wouldn't be rubbing on anything and that's the issue with those types of paints. The abrasion resistance is about non existant.

I'd think you'd not need more than a couple of pints for the outdrive maybe that much for the transom but likely less...

That paint goes along way. A gallon and a half will paint most good sized cars. I have an old VW bug that didn't take much more than 1/2 gallon and I sprayed 4 coats on it....

Also the automotive paint will flash real quick as the reducers and hardeners are offered in different speeds. Helps to keep the dust bunnies and bugs out of the paint too.

 

[fishrdan]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

One note, you said you would be using an oil heater to keep parts warm. I do not know about Rustoleum but many paints will have a bad interaction with the oil fumes from those heaters.

It's one of those electric heaters with and oil filled radiator, not an oil fueled heater, so all should be OK,,, I hope

 

[fishrdan]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

Sounds good, I'll stick with the Rustoleum for the outdrive and transom assy and will definably be using PPG for the hull touch-ups.

 

[tashasdaddy]

Re: ? Spraying Rustoleum in cold weather,,, how long to harden

i have never had to paint below 70*, so can't help.