Painting a powder coated fence

[Timed Out]

Hi all

I have a black powder coated tubular steel fence that's in need of painting. The finish has dulled off and it has some scrapes and scratches.

I'm looking at applying a gloss enamel finish but need some advise about how best to prep the powder coated surface.

Would a light sand followed by a metal primer such as Wattyl Super Etch do the job?

Any advise or tips much appreciated.

[munruben]

You might be better off giving the fence a good wash with warm water and detergent to bring it back to life, You can purchase touch up paint from your local Colorbond outlet for those small scratches you may have.
After washing, you can even apply a wax polish and make it look like new if you want to go to that effort.
If you go ahead and paint it, seek advice from the fence manufacturer to see what they suggest. Enamel paints chip badly.

[Bleedin Thumb]

Would a light sand followed by a metal primer such as Wattyl Super Etch do the job?

.

No. you wont get the enamel or acrylic to stick to the powder coat.

The only time I've had to do it I ended getting the stuff sandblasted off then resprayed = costly.

You could try using some Zinsser BIN primer. Go to their web site and if that doesnt tell you leave an email query and someone will get back to you with an answer - very helpful company.

[durwood]

Powder coating is no more difficult to paint over than any other paint.

Its hard and smooth so you need to rub it with fine paper to allow the following coats to adhere. It's way easier to paint over than say baked enamel and it can be successfully painted over.

Its quite possible its got normal paint on it already. for if the powder coating is not applied everywhere properly they don't redo it they get out the pressure pack can or spray gun and touch up the bald spots.

There are two types of powder coating, the most common is a thermoplastic one the other is thermosetting. What this means is one melts into a plastic coating that can be resofted with heat again the setting version sets like baked enamel and becomes glass hard.

You can test for this by rubbing it with a strong thinner ( acrylic Lacquer it the strongest one easily available) If its termoplastic it will become tacky. If this is the case you can apply acrylic lacquer to it ( primer followed by colour) and it won't fall off as the thinner will melt into the powder coating and give excellent adhesion. Only problem is you have to spray the paint which means a lot of waste paint on a fence as you miss a lot as the fence is made up of skinney bars etc.

If its thermo setting you will have to rely on the sanded surface and a suitable primer which will adhere well. An epoxy or a 2 pack primer would work best but a good primer for enamel should also stick properly if the surface is clean and sanded. Its more likely your fence is thermoplastic. Metal primer and etch are for metal surfaces use a primer for paint not metal.

If you are leaving the fence the same colour I would spend a bit more time sanding and cleaning throughly and skip the primer and just put the black onto the black powder coat that way it will be quicker and easier and if you miss a small spot will be unnoticable Tube fencing is a pain to paint neally as bad as lace work wrought iron.

I would have no hesitation painting a powder coated surface with normal enamel gloss house paint as it naturally sticks to anything if its dry and clean. Its probably its greatest advantage as its one of the only paints which will give great results with virtually no preperation.

eg: If you want to paint your car wash it off give it a bit of a clean to remove any wax mask it spray it with enamel and you will be highly unlikely to ever have problems with adhesion vsanding help more but that takes extra time so its usually not done unless there are scratches or rough spots.

Its the paint used to give you those cheap resprays you see. It doesn't matter what is already on the vehicle it can be any paint and the enamel will go over it perfectly. Not so with most others, put the wrong one on top of another and all hell will break loose.

I'm sure most forum members at some stage have given the odd piece of house trim/steel etc a quick rub or clean to remove a bit of rust and dabbed a coat of enamel onto the surface ending up with a coat of paint that lasted for years.

[Bleedin Thumb]

Well I stand corrected.... I will bow to your greater knowledge on the matter Durwood. All I know is that when I tried to paint 25 or so bollards at one stage I couldn't get paint to stick for love or money and had to send them to the sandblasters and believe me I wouldn't go to that (out of pocket) expense unless it was a last resort.

Any way I accept that Durwood does know more than myself about these matters.

[munruben]

I would have no hesitation painting a powder coated surface with normal enamel gloss house paint as it naturally sticks to anything if its dry and clean. Its probably its greatest advantage as its one of the only paints which will give great results with virtually no preperation.

I certainly wouldn't go down that path myself with household enamel paint.

Indeed, there are problems recoating certain powder coatings formulated with a slip agent to inhibit mar resistance. These slip agent come to the surface during cure. Many of these slip agents can be removed by solvent wiping or surface scuffing the powder coating.

As for painting a car today with enamel paint I shudder to think what it would look like after a few years Most new cars leave the factory in a 2K car paint finish. However, metallic colours and some cars new solid colours are base-coat and clear. 2K means 2 components are mixed together i.e. paint and hardener, then either air dried or baked. The metallic base-coats are made in polyester and are applied after having added thinners, then the lacquer is sprayed on separately - I have painted cars in the past with enamel but we have moved on since those days, thankfully.

[durwood]

Guys, I didn't mean to contradict anything you posted and I think I steered this thread away from Timed Out's question a bit but he did ask about using enamel for his fence. I was just offering examples of why it would work. So I hope you will excuse me for going off even further but often members are looking for answers and the following may be of some use for them.

There are always exceptions to the rules and I suspect Bleeding Thumb must have gotten one of them. Obviously whatever was on the bollards was a bit more than the normal powder coat. Sounds like they may have had a silicone or similar coating on the surface. There have been several products marketed and since withdrawn because of problems such as BT struck. What type of paint were you trying to paint them with BT? was it water based?

Munruben, I did mention that putting enamel on a car was a "cheap finish" being such a cheap material it costs little to buy, needs little work to prepare the surface and produces a good finish over poor surfaces and isn't the normal choise for someone looking to restore their car properly. I wasn't recommending it was the way to go to paint your car.

It never the less is still used for lots of things. In Sydney there are several workshops who specialise in doing quick one day resprays for a few Dollars. If you need to tart up the old bomb for rego a quick glossy coat of enamel works wornders. I know of one guy who regurally changed the colour of his car to avoid detection by the local police.

A lot of businesses that have vehicles which are treated badly or subject to rough treatment also often get the quickie respray. Several councils have always used it for their garbage trucks which tend to get covered in all sorts of horrible things during rounds. A quick wash and a mask and a spray and next day the crew has what looks like a brand new truck. I don't think there are many box trailer manufacturers who don't hit their creations with a coat of enamel once finished often without even cleaning the metal or primering.

Yes, it doesn't last long usually because its treated like it is a cheap coat of paint so its not washed or otherwise looked after but it does work well and is still recommended by most paint companies for trim work on your house. By the way I have a car in my garage which was painted 31 years ago in Maroon air dry enamel which still is in such good condition it doesn't look like needeing to be painted any time soon, but it is garaged, polished and covered up when not out on the road.

As for new cars virtually all are still finished in a baking enamel ( one that requires heat to set the paint) the 2k versions are used by repairers as its not possible to bake the car once its assembled (glass, rubber, plastic, not able to withstand the 200 C plus temperature required) Smaller companies use it as the new finish as the equipment cost is a fraction of that needed to bake. Ford Australia actually did use 2k on there Fairlane range assembled in Brisbane during the old XD days but you have to go to the small hand built cars like Morgan,etc or fibreglass bodied ones to find it other wise.

The hardener sets the Acrylic Urethane paint to give a finish which is as durable as the original baked enamel . Often you will see panel beaters advertise they have baking ovens but they are only forcing it to dry as you can't go much above a hot day (60 C or things start to be affected by the heat).

2K finishes are not often used in new car factories as you have a pot life with the paint once the hardener is added. This means that the guns and hoses have to be washed out all the time. with the baked enamel the paint can stay in the paint lines and be recycled day and night until its sprayed on and baked.

I think you mixed up a bit on your descriptions, solid colours and the COB process (clear over base). You can have 2k colours which are straight such as black, blue red etc. which are mixed with hardener and they are applied as a final coat. usually about 2-3 coats, they are then the final finish.

Base colours which can be metallic, pearl, multi layered or solid colours are sprayed on without any hardener (polyester or acrylic based - just solvent thinned as you said) followed by clear 2K urethane enamel which when dry produces the same coating as the normal 2k colours. This is what most car companies are moving towards as they have to establish a separate area to clear and now we are getting super scratch resistant clears so all the colours are going to be COB soon.

The reason for using COB is to get the paint to cover the primer quickly due to its great opacity. Doing this means you can block out the primer or add different layers of different effects with little paint (such as pearl which is usually a base colour and then a pearl colour on to and maybe a transparent colour on top again with out getting runs and sags as it dries fast and is thin) but it has no gloss when it dries and it is weak as solvent will wash it off so the 2k clear protects the end result and provides the gloss.

Sorry if I have messed a "home renovation "thread into a "motor vehicle" one

[Timed Out]

Thanks for your replies. Sounds like etch primer is not needed as I won't be taking the fence back to bare metal.

I have a surplus fence panel so I might use this to try your suggestions before embarking on the entire job.

In the durablility stakes is an an exterior gloss acrylic better than enamel gloss?

[munruben]

Sorry if I have messed a "home renovation "thread into a "motor vehicle" one

Thats not a problem.your comments are welcome. The whole idea of these forums is for us to seek advice and offer advice among other things and I think we all offer our advice to the best of our knowledge and we can only speak from our own experiences but of course that doesn't necessarily mean that what we say, even though with good intention, is gospel and should be followed to the letter. Everyones input is most welcome and it wouldn't be very interesting if we were all in agreement all the time.

[aspectdisplays]

Timed out,
Have a look at some of the paint makers web sites. I had this problem a while back having to rejuvenate a display stand that was powder coated. I’m not sure if it was Solver or Dulux etc. but one of the sites runs through question and answer of substrate, previous coating desired finish etc. Then gives you the required preparation and products needed.
I have been told by the powder coater that I use that they really need to sand blast if they are going to re-powdercoat as it doesn't perform well going over the top of previous powder coating. I did however get a good finish on the job I did, I remember the top coat was enamel but can't remember what was applied first.

[Timed Out]

Went to Bunnies last weekend and picked out who I thought to be the oldest and wisest looking person in their paint dept. He said a standard exterior gloss acrylic will do the job. With this bit of advise I purchased a small tin of Dulux Weathershield to see if he was right.

Started off by painting an unused section of fence panel and sure enough it went on fine. I soon realised though that the job of painting all 30 metres of the tubular steel fence would take me an age.

Take 2 - Munruben suggested giving the fence a rub with some car polish so I went to the shed and pulled out a tin of cut and polish. +

It works a treat.

The finish is coming up shiny again. no brush marks and it's way faster than painting. All I have to do after the polishing process is touch-up the nicks and scratches using the tin of gloss acrylic.

Thanks Munruben.