is it possible to apply paint to powder coat and, if so, does it just need a good key before base coat or it best to apply a primer after keying? It's a Honda frame that was powder coated a year or two ago but it still needs some light filling to make good.

email (option): lee@twowheelstested.co.uk

I decided a while back to powder coat before painting as it provides such a good 'base'...

On the first bike I built using this method I just over sprayed the powder coat...Not a good plan as I found out later...The paint could be damaged quite easily due to the poor bond between the two layers...

The next bike I lightly rubbed back the powder coat sufficient to provide a good 'key'...I used a relatively course paper for this (240 grit)..

That seemed to solve the problem though care has to be taken to get into all the corners etc..

Now I get the parts coated in a high zinc base coat powder and flat them back as described before spraying....

If you want to really protect it beyond that, finish of with a couple of coats of clear coat lacquer...

I have sprayed over powder coat with synthetic, two pack and cellulose at different times without any reaction problems...Ian

email (option): ian@wright52.plus.com

i use halfords hammerite smooth stone chip on everything (spray can) normally grey, they also do black so prob a good base for your frame, spray on a few coats so nice and thick, give 5-10 mins between coats, leave a couple of days to go hard, then wet sand with say 400 grit paper, it will take out any pitting ect, you can over paint this with any paint you like with no problems and gives a good hard base, make sure you give the powder coat a good key with say red scotch pads or 180-320 grit sand paper, a always use DA discs by hand.

hope this helps

thanks, barry

email (option): fullerbarry@hotmail.co.uk

Thanks Ian & Barry, it's much appreciated. Powder coat looks to be a good base as the frame was incredibly rusty and after coating, and is still sound a year or two later. I'll get the 240 discs out and give it a go

Well I will be the fly in the ointment.
Powder coating is a PROCESS not a PRODUCT.
There are almost as may types of powder coatings as there are types of paint

That cloths airer on the rear porch with the coating that broke up fell off & got stuck in your Y fronts was POWDER COATED as was the cheap garden chair with the lumps of coating that got stuck in your bum was also POWDER COATED.
Some POWDER COATINGS are oxides and fully vitrify like on yer cast iron bath tub. They are hard and bond perminantly to the surface while others are just ground up plastic that in effect laminates the product, is soft has almost no abrasion resistance and does not bond to the surface at all and just about every where inbetween.

So it is going to depend what the powder coating is and what the paint you want to top coat is and in particular how hard / brittle each one is in respect to each other.
A hard coating over a soft powder coat will star crack every time too much pressure is applied which is exactly what happened when 2 pack was first introduced becaue the original undercoats were not hard enough. We all remember that don't we every bolt buggered the paint and the tank had cracks radiating out from the fuel cap. Put 2 pack paint 10 years.

Powder coating is a very poor base coat for a frame. All types are too thick and will not penetrate fine cracks like where a bracket is only partially braised onto the frame and like plating suffers from Faraday cages on internal corners only to a lesser extent.

If you really want to protect your frame, get it chemically stripped the POR 15 Chassis coat for the undercoat.
Not only will bullets bounce off POR 15 it chemically bonds to any stray water molecules ( including the ones forming rust ) and protects your frame forever.
It is thinner than water and will get down into every nook & cranney, including all the old worn threads. thus tightening them up, truely, does wonders to those loose oil tank, mudguard & battery mount holes.
Once fully hardened ( 4 days ) you can not get it off and every paint will adhere to it.

The only downside is it is not UV stable so if the bare undercoat is left sitting in the sun for a month it will powder off but then it is a base coat and you are going to paint over the top of it.

email (option): bsansw1@tpg.com.au

I think this is more a case of language rather than the fact that anyone doesn't know powder coating is a 'process'....

It's easier to say.. 'I'm painting over powder coating'... than it is to say.. 'I'm painting over an electrically charged powder that has been applied to my frame and heated to approx. 280 degrees at which point it became liquid, solidifying once cooled'.... ....Ian

email (option): ian@wright52.plus.com

I have had success overspraying with Hammerite Smooth (Smoothrite) and then cutting it back to infill chips or scratches but a couple of points: infilling works best with the standard paint applied by brush and rubbing down needs to be left for as long as possible for the Hammerite to cure. I err on the side of caution and leave 6 weeks but my workshop is stone built and cold, it may go off quicker when warmer!
REgards, Mark

Has anyone tried their fuel tank kit with modern fuels?

email (option): jonny.rudge@verizon.net

Ian Wright

I think this is more a case of language rather than the fact that anyone doesn't know powder coating is a 'process'....

It's easier to say.. 'I'm painting over powder coating'... than it is to say.. 'I'm painting over an electrically charged powder that has been applied to my frame and heated to approx. 280 degrees at which point it became liquid, solidifying once cooled'.... ....Ian

email (option): bsansw1@tpg.com.au

There's the rub: here in the U.S. all fuel is at least 10% ethanol so it eats the tank and most liners. The closest place to me with ethanol-free fuel is 140 miles away so I have to spend a tankful to get a tankful!

email (option): jonny.rudge@verizon.net

I suppose if you take your parts to a firm who specialise in powder coating motorcycle parts, they should use the correct process?

My own experience of a bike that was powder coated and over painted is not good! The paint and powder coat will chip off every-time you undo and re-tighten the fixings, or if the bike is bumped it can leave a deep chip to bare metal.

I never bother with it myself! I prefer zinc based red oxide primer or 2 pack high build primer, both of which can be built up and then rubbed back with wet and dry paper to remove pitting.

Ron

email (option): ronpier@talk21.com

Just my pennies worth on the subject as it's already gone off at a bit of a tangent!

My view would be if it wasn't powder coated when it left the factory it shouldn't be done now.
If you a restoring a vintage bike in particular it shouldn't be done as i believe anyone willing to pay you top money if you want to sell it in the future will want as factory finish.
No matter what type of powder coating, you cannot allow for surface preparation(ie filling pitting) before powder coating is done, i know you can get high temperature polyester fillers but these seldom hold there own when put in the oven and you end up with a blistered finish.
The best results i have achieved are through blasting firstly, priming with a zinc based primer and then p38 filling deeper pitted areas, followed by up to six coats of 2 pack high build primer, sanding between each coat with 600 grade w/d and then top coat.

I have also lead filled pitting for better bikes, and this can only be done straight after blasting before priming, also if you cant do it straight away you need to keep the parts warm and dry, and gloves on if you have rusty fingers!!
Lead filling can be done before powder coating but not for the higher temp finishes and you will never fill all the pits.

If you want a really good finish you just have to put the time and effort in.

Grahame

I guess if it's powder coated and there are no pits you know you have sound components....

It's probably best not to get into a discussion of what is original and what isn't on a modern restoration...

However, many original parts were stove enamelled, not sprayed, so it could be argued that spraying using modern paints, fillers, lacquers etc. is no more original than a powder coated finish..

I had the frame powder coated for my B33 in 1978..38 years ago..and apart from some minor deterioration/damage in places it is still entirely serviceable...

A friend of mine recently had the frame for his Triton powder coated with one of the new high gloss powders and IMO the finish is superb...

I'll certainly be using it for my Triumph T120 in the near future...If that lasts 38 years as well it will more than likely outlast me..Somehow I don't think I'll make it to 99..



Ian...

email (option): ian@wright52.plus.com

There is nothing worse than shiny pits !
Why people exaggerate the pits with a nice shiny finish, is beyond me ?

Yes power coating (usually a polyester two pack - for gods sake don't use the softer polyprop finish sometimes offered) is a very good base coat.
But be careful - it very easy to w/dry the finish down to bare metal while trying to fill in the pits.

My powder coater/blaster will allow me to take the frame away after blasting, so i can paint with a high build filler (or even let the coater do it for you) - he specifies what to use, i get a local paint shop to mix it for me - to brush coat.

Brushing stops all the dead-spray which used to plague my workshop, and allows a nice thick coat.
You can then save money by doing the rubbing down yourself - i suggest you get into audio-books - it will pass the hours more quickly!

Then once adequately filled - back to the power-coater's and voila.


Prior to the above process, i used to get it power-coated, then rattle-can spray with high build, then rub it down
(light grey filler against black powder coat lets you ID the pits)
Once smooth - i brush painted the top coat, the problem was i kept breaking through to bare metal - rather wasting the powder coat process.
I now only use this process on my early bikes which can look s**t with a sprayed finish

I got one of my bikes stove enameled 25 years ago. Very expensive as its so labour intensive, all that rubbing down and smoothing to get rid of the pits. But the finish is still superb now. The only problem is I think all the stove enamellers are now out of business, I know mine is, anyone know of any old school places still operating?

Where are you based Keith?..There are still some stove enamellers about...A pal of mine has just had the parts for his latest project done..

He is in Newark on Trent...Ian

email (option): ian@wright52.plus.com

Hi Ian , I've just done a Google and it seems my old enameller is still around, they've moved to "new" premises. C & G finishes liverpool. So i;m sorted for my next project, just got to save up for a couple of years!

Yes a friend of mine (Dino) is restoring a 38 Triumph Speedtwin to concourse and absolute correct specs and getting parts stove enamelled. Southampton I think, but I will check. Ron

email (option): ronpier@talk21.com