Touching up powdercoating

Ed. note: We have no photos from you jojo. Please email them to mooney@finishing.com for posting here.

A. Need the images to see what this is, but there are various touch up systems involving aerosol alkyd paints available and widely used.

Ed. note: Generic types of paint only, please, gentle readers -- not brands or sources! (why?)

A. Dear Sir,

Use repair kits that exist of a liquid 2-Component paint. Ask your powder supplier for these repair-kits.

Hope to have been of help.

A. I have been experimenting with mixing the powder with paint thinner and then brushing it on, baking it and then sanding off the excess. If you have any other ideas please let me know. The parts I am powder coating are for outside use and paint does not hold up as well.

A. We have had some success mixing a little bit of the powder we use in some acetone ⇦ this on eBay or Amazon [affil links] Warning! highly Flammable! or M.E.K. This is good only for color though and will not reproduce texture. This mixture can be brushed or sprayed on.

A. We have found mixing powder with paint thinners to be suitable for us, although this method will not work with metallic colors. We are using polyester powder.

A. The best way to repair damaged powder coating on either a head or other powder coated components on any motorcycle is to remove the affected part and have the powder professionally removed and re-powdered. This can be done by several job shops in the United States. There are a few that can remove powder from aluminum parts and most can remove powder from steel parts without affecting the surface of the part.

A. Maybe no problem James. Most powder coating can be touched up with regular paint. It would surprise me if the manufacturer does not offer those little bottles of touchup paint. But if they don't, take it to a consumer-friendly powder coating shop; they will know what to do. Good luck.

A. Sure, Eric, most powder coating is easily touched up with liquid paint. There is not necessarily any compatibility issue. This repair may not be perfect, as earlier responders have noted, but it will improve the looks and the corrosion resistance of the scratched area. Good luck.

Q. Our customers require us to assemble Powder Coated parts. Sometimes they are pitted or damaged. Is there a way to touch-up Powder Coating or Handling defects?

A. Dear Mr A Korlselman,

This query has been answered by me on an earlier letter but at the risk of repeating myself here goes:

Dissolve the same powder used in the coating in TC or any NC based thinner in which the powder dissolves. Touch up the scratched area with the resultant Paint /paste/liquid powder whatever you call it with a suitable paint brush.

Experience will give you an idea of how much your Solvent/ powder mix should be.

All the best,

Regards, K Vahanwala

A. I have seen a very good method of touching up hook marks like you describe. There is a manufacturer close to us who makes a thermoplastic patch stick which fits into a typical hot-glue gun. You simply melt it onto the mark like you are glueing parts together. Maybe someone close to you makes this type of product. It is much faster than waiting for a liquid touch-up to dry.

A. Hi,
Most powder coaters use aerosol car spray paint or a small pot of car paint and brush.

A. Caleb, it sounds like you are saying that you try to touch up powder coating flaws by re-applying powder to the flawed area and then re-curing it causing the first coat to over-cure and change color. The proper way to fix a powder paint reject is to sand (or chemically strip) the whole part, not just the bad area, and then repaint it.
There are aerosol suppliers that will match the powder you are using so that you can do touch-ups.
Some powder suppliers match their own powders in aerosol, so you might want to ask your rep if they provide that service, or maybe he can recommend someone to you.

A. Spot touch up is the best solution for very small areas. For larger areas, it is best to touch up with a Pu based automotive paint (gives good performance over these areas).

Q. Mr. Amit,
Sorry for responding to you belatedly since I was out of station. First I thank you for sparing your valuable time and answering my question. Kindly tell me what paint I should use for spot touch up? Also tell me whether PU spray painted parts instead of powder coating would give the same results in all terms? Have a good day! Thank you once again.

A. Hi Sivakumar. We merged your inquiry into a thread which offers lots of perspectives on the situation. However, no, a touchup will never be as durable as the original powder coating (consider that the scratch may have also scribed through the pretreatment). If you need perfection, you need to strip the powder coating and start over. Sorry.

Regards,

RFQ: I need touch up paints for Rohm & Haas powder coat colors Textra Black Sand and Textra Chestnut.

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)

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Ed. note: Current, active RFQs are now on our "Looking for Products & Services for Our Finishing Shop" page.

A. Hi Venkat. Waxing/polishing sounds like the easiest approach for faintest marks. For deeper marks, the rubbing compound ⇦ this on eBay or Amazon [affil links] and scratch removers sold in auto stores should do it. Where the powder coating is deeply scored or missing, then touching up as described by Khozem and others above should work.

Regards,

A. Hi Varun. We appended your inquiry to an earlier thread with some helpful ideas. Remmelt Bosklopper's idea of spraying a 2-part coating (such as an automotive clearcoat) on the poorly coated and non-visible area sounded good to me :-)

Regards,

A. Partial re-spray with powder usually adds to the problem. The partial overspray onto already coated parts causes a grittiness in the coating loosing gloss. If using powder, then full respray. Don't forget adhesion. What will be the adhesion mechanism of your new top coat to the original coating? Better to sand it to get a key between coats.
Alternatively, used a matched colour liquid paint as touchup from an aerosol.

Green Powder Coating Tape

eBay or

Amazon

(affil links)

I hear a lot of answers saying to sand before applying a second coat or color change.
From experience I'd like to add some helpful tidbits of information for anyone seeking an answer to recoating a piece that's already been coated.
If you have a media blaster / sand or other and you have experience with it, you can save a lot of time and effort by preparing the surface by hitting it with a media that won't take the powder coat off it, simply prepares it for another coat.
One of the most important things to remember when recoating is the piece might be difficult to get a connection to complete the statically charged surface. What I do when I'm in doubt is to preheat the piece at about 250 °F.
It can be tricky to manage but if you are properly set up, you will be able to do this with ease. use a low bar settings on your gun and dust it with a generous coating of the color you've selected. Put it back in the oven and bring it up to temp for 5 minutes, then shut the oven off and let everything cool untouched.
The surface coating will be very well adhered to the substrate powder coat. You can use this same method for multicolor applications, using masking tape. If you are familiar with pinstriping tape, that is the type of accuracy and delicacy it takes to work with a warm to hot precoated part. No fingers can touch the surface. have your tape prepared and your piece stable enough to work on. I have multiple fixtures from wire hangers to grates to magnets that I use to stabilize, hang or secure to work on. You might find that an assortment of magnets very handy. They can hold a hot piece through a precoat and take a fair amount of heat.
You can make electromagnets very easily that works off a switch and is unaffected by the temps normally required for general powder coating.
With a little practice and patience you will find that magnets will help the powder to adhere using them to enhance the electrostatic. Those are my helpful tidbits of intell.
I am self taught and I build hot rods. I have powdercoated parts that others said would stand up to the test of time, wear and tear, and I, as they are amazed. Through some simple enhancements you can make a bond that is virtually impenetrable through heat cycles knocks and bangs from wrenches etc, holding up amazingly well.
Practice on awkward shapes, multicolor, masking and plugging areas to keep uncoated, or to keep a base color. Have fun with it. Stop at the dollar store and buy things in the kitchen utensil department that will challenge you. Nothing ventured nothing gained.

A. Hi James. I think Khozem's posting is the most applicable response to your situation, but "indistinguishable" is an awfully tall order, the more so for a texture paint :-)

Luck and Regards,

A. The answer is No.
If you re-coat, you will overbake the initial coat leading to brittleness and loss of properties.
Best to strip back to bare metal either chemically or mechanically and re-process with more care.
Hope this helps.
Regards,
Bill

2K Clearcoat

on eBay or

Amazon

(affil links)

A. Hi Mackenzie. Metal is harder than organic coatings like powder coating or clearcoats, so the problem is not 100% solvable. But the hardest coating you will be able to conveniently apply on top of that powder coating is probably a two-component automotive clearcoat (the chemical reaction makes for a harder cure than you would get from evaporation of wet paint or clearcoat, and I think you want to avoid baking or UV exposure).

I haven't tried it, but there is a two-component clearcoat in spray cans that should be worth trying if you can't get an automotive painter in there to mix and spray with professional equipment. Good luck.

Regards,

? Hi Ganesh. Hopefully another reader will prove more insightful than me, but I don't think I would even know how to try to offer any help without you more clearly describing the defect and some background facts, and seeing pictures of the oil mark (e-mailed to mooney@finishing.com). Sorry, but I simply have no suggestions except stripping the powder, re-cleaning the part, pretreating it, and powder coating it again. Good luck.

Regards,