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Conductive (metal?) Filler Needed before Powdercoating


Q. We are currently powdercoating some parts for a company who is experiencing problems with pinholes in the welds and with lines and marks on the steel of the product. Our process is to sandblast the parts to remove the metal scale before powdercoating, but this is not removing these marks . This customer is very concerned about the smoothness of the finish and is wondering if there is anyway that we can fill these pinholes and smooth out the metal. We have not successfully found any type of metal filler that will withstand the temperatures needed to cure powdercoat and be unnoticeable after curing.

Does anyone know of such a product...

... or have any other suggestions? We have already suggested that they check with the welder to see if any of these problems can be eliminated before the parts ship to us, but they are still asking us to check in to using a filler of some sort.

Tammi L deleted
- Cedar Rapids, Iowa


A. Dear Tammi, I have used a two-part component made by 3M. It can air dry or be stoved to around 375-400 degrees. I cannot remember the exact product name or number but it works well. It can only be used for very small pinholes (1/8" or less) due to the non-conductivity of the filler. . Try it! I think it will work for you...Bob

Bob Utech
Benson, Minnesota

Editor's note: 
Mr. Utech is
the author of -->

A Guide to High Performance Powder Coating
[link is to this book on Amazon]


A. Tammi:

There is also a filler made by a company called DEVCON. I am not sure of the name. It is an aluminum-filled epoxy that withstands a good amount of heat. [Ed. note: perhaps Devcon #10610 Aluminum Putty] Once product is mixed, you have approximately 30 minutes to apply. Cure for at least 1 hour at 150 °F. When cooled, you can sand or grind smooth.

A company called HYSOL manufactures a similar product: EA-934. Can be worked just like the above material.

I use these products to fill holes in alum., steel, etc. that have been drilled in the wrong places. (Hey,it happens!)

It can be machined also.

Good Luck!

Patrick Ldeleted


A. Tammi,

There is a two-component epoxy putty on the market called TIGER DRYLAC - EPO STRONG. This putty has been developed by a powder coating manufacturer and features excellent heat resistance (up to 450 °F), no shrinking and excellent conductivity for powder coating.

Thomas F. Gratz

St. Charles, Illinois


A. Dear Tammi

if you still have pinhole problems, a solution is to increase the heat in your pre-stove oven. This will swell the metal, and while the item is very hot then coat it. After stoving you will find the pinholes are not existent.

Vince M deleted
freelance - England


A. We have a metal filler or powder coating filler called Thermobond 3. This product was made just for powder coating applications.

Coleen Sirois
- Lake Elsinore, California

July 21, 2011

A. Consider Alvin Products Lab metal and Hi Temp Lab metal.

Dennis Aikman
- Everett, Massachusetts, USA


Q. Technical assistance required for the types of and the correct processes for using auto body fillers that would subsequently be powder coated.

Specific problem: Material - Binhai Donghao Compound Material Co., Rapid Dry Putty and Rapid Dry Catalyst (2 catalyst and 100 putty mix together), Type: 951-001 Spec. Q/32092BDH-96
Cure period: 1/2 hr. at 77 °F., relative humidity 60%. Shelf life: 6 mo.

The auto body filler (2-part material, catalyst and putty) is not curing at a consistent rate. If the ambient environment is warm and dry it hardens sufficient for sanding within 1 hr. at 77 °F., relative humidity at 60%. If the ambient environment is cold and humid it will take from 6 to 8 hrs. to harden. Why does this happen and how do I keep the drying process consistent?

The product substrate is welded and then shot peened hot rolled steel. The body filler is applied to correct any minor cosmetic defects on the outside surfaces. The product is then powder coated in convection ovens.

Peter Woodworth
Sentry Group - Rochester, New York, USA


Q. We use a titanium putty on some sheetmetal products that we manufacture to fill some gaps where we join parts by welding. However, sometimes the putty bubbles up and some times it does not. Does anybody else out there know of a filler that can be used under the powdercoat that gets baked at 200 °C.

Mark Chandler
- Melbourne, Australia


A. Peter,

Any two-part fillers using a catalyst depend on a chemical reaction between the parts to harden. Single-component coatings, like paint, count on a solvent evaporating. Since chemical activity is temperature dependent, epoxies and other two-part fillers take longer to 'set' or catalyze at lower temperatures. Epoxies seem to be quite non-linear in this respect, for instance a 30 °F temperature drop may cause cure time to go from 2 Hrs to 24 Hrs. So, to stabilize cure time, stabilize the temperature.


Since the putty you are using 'sometimes' works fine and other times 'bubbles up', I suspect a curing problem. If it doesn't cure completely before baking, the volatile components will boil out, showing up as blisters when they can't get through the surface. Try warming the workpiece on the non-putty side after application and see if that helps. Also you didn't say if the putty was a two-component compound or not. In any case, make sure it is thoroughly mixed before use. If it's two-component, the components must be in intimate contact for proper curing. One-component fillers may separate in the container and have different amounts of volatiles when applied.

Tom Gallant
- Long Beach, California, USA

To minimize duplication and the effort required to find answers, the editors have merged together several formerly separate threads. The participants in the threads below may not have seen or remembered the thread above, and vice versa.


Q. I am interested in learning what conductive putties or fillers can be used on parts with porous or rough surfaces that would still be able to withstand normal 400 degree/20 minute reflow temperature cycles.

Greg Sample
- Wilsonville, Oregon


Q. I need to know if anyone has a suggestion for a powdercoat filler to cover surface imperfections in steel. Bondo won't do as it emits gasses that won't allow good adhesion.

Wyatt Buchanan
binghamton, New York


A. Although maybe not too efficient for large scale operation, when we have a few parts that have pits, we use a Metal Repair Stik made by Permatex [Permatex Multi-metal Epoxy Stickamazoninfo]. It's a small roll of 2 components that you pinch off, roll into a well mixed ball, and smooth onto the imperfection. While it is still soft, we can smooth it with just a good rub of the finger. Good luck.

Paul Norman
- Odessa, Texas


A. Alvin products Lab-metal [linked by editor to product info at Amazon] is the stuff I have used.

Joe Smith
- Portland, Oregon





Q. If anyone in India is reading, please help me too find a similar product which is available locally here.

khozema Khozema Vahanwala
Saify Ind
Bangalore, Karnataka, India


A. Pin holes or surface imperfections can be filled with epoxies or structural adhesives which allow painting.

For the Gentleman from India who wanted to know a source of these products:
Permatex is available through Timken Bearings India and Permabond products through JJ Gandhi Chemicals Mumbai.

satish agrawal
Satish Agrawal
- Visakhapatnam, AP, India

January 31, 2013

Metal filler putty "Piocol Fixup" is available in India from M/s.Prkntek Engineering solutions Pvt Ltd. Mumbai.

Joseph Maney
- Mumbai-India.


Q. I am working on restoring a motorcycle and want to re-powdercoat the frame. Unfortunately, there is a dent about 2 inches long in the tube steel and I would like to smooth it out prior to coating. Is there a material which can be used to fill in this large of an area and still achieve proper bonding?

RFQ: As I do not have the proper materials for doing this myself, I would welcome suggestions as to where I could get this done in my area.

Brian McDowell
- Hillsboro, Oregon


A. Brian-

We have had good success with a product called All Metal [linked by editor to product info on Ebay]. Check out an auto body or auto paint supply store, look for Bondo-type products that have aluminum or titanium materials in the mix. They ARE out there, sometimes hard to find, though. They are easy for you to apply yourself, if you have any experience with Bondoamazoninfo filling and feathering.

Hope this helps...

Lynn Hughes
- Kent, Washington


Q. I am interested in the discussion of filling underneath powder coating. I am working on a project to convert a range of sheet metal parts from a painted to a powder coated finish. Unfortunately the parts have very high cosmetic appearance standards and we have found it impossible so far to find a filler that completely covers up joints and fasteners under the surface of the powder coat without leaving a visible line or indentation. This problem appears to be electrostatic as it is visible before the powder is baked and does not occur where there is continuous metal under the filler (e.g around studs). We have tried a range of conductive fillers and it seems the more conductive the surface the better, but we don't have a solution yet. Can anyone suggest a product that works?

Tim McLean
- Melbourne, Victoria, Australia


A. We've appended your inquiry to a thread where many vendors have been suggested, Tim. I think the best strategy may be to pick a promising one and work closely with that vendor towards a solution. Best of luck.

Readers: We apologize if this thread is looking a bit stilted, but this forum works very well on technical issues and very poorly on sourcing issues where there is potential commercial gain. Sales people took the opportunity to describe their offerings in effusive terms, with each subsequently feeling obligated to outdo the previous; and next came the phony testimonials submitted with fictitious names... :-)
So we had to go back to the beginning, remove all the testimonials, and just leave bare names of potential sources which people can google. We'll post names of additional potential sources as they are submitted -- but no testimonials! Sorry, but there is just no way for us to tell the genuine helpers from the phony plants :-(

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Brick, New Jersey

Need flawless filler for vintage dirt bikes


Q. I'm trying to restore gas tanks for vintage dirt bikes. Many are old and have a lot of dents and dings and they also MUST be powder coated. I finished 4 and sent them to the local powder coaters and when they came back, everywhere I had feathered the filler it had raised up. I used a metal to metal filler (on the same basis as J-B Weldamazoninfo ). Since these tanks are for vintage bikes, they need to be flawless, or close to it, but the tanks I received are far from it. I asked some local businesses and some said to use JB Weld, others have hinted about filling with lead, but I haven't came across a concrete answer and I can't take anymore chances with lifted filler and wasted money and time, and I also have a deadline. PLEASE HELP!

Justin Wellman
auto body tech - Columbiana, Ohio


A. The best approach may be to have the powder coater do the filling and be responsible for it because it otherwise the origin of the problem always remains debatable. Although there is no guarantee that will achieve success just because some other body technician and some other powder coating shop have done so, we appended your inquiry to a similar thread, so please review the above suggestions for some recommendations. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Brick, New Jersey


A. Good day, Have your coaters check with their powder manufacturers: some new, low temp paints are available that might allow you to coat over certain fillers without ruining the paint job. A typical job shop will give you a typical powder coating cure of 30 min @ 400 °F -- much too high for most fillers.
It's not a restoration if you are powder coating; if you apply coatings that are original to the machine, it will be a lot less expensive and will make the bikes more valuable. If you are allowed to powder coat, than you should be allowed to re-pop some new tanks, then you wouldn't have to worry about dents and stuff.

Sheldon Taylor
   supply chain electronics
Wake Forest, North Carolina


Q. Hello everyone!

I hope someone can help me.

I have some sheet metal parts that I'm going to powder coat. Those parts have flush PEM's studs inserted. After powder coating, the heads are visible. The part is very cosmetic and I need to cover the groove between the stud head and the steel metal.

Could you help me?


Dany O. Portales
Monterrey Metal Products - Monterrey, NL, Mexico


A. Apply a heavy coat of powder only to the area with the stud head(to fill the groove), cure it, sand it, then paint the entire part. Fast, easy and cheap. What's more compatible with powder than powder? This way you don't have to introduce a new product or process into the shop.

Sheldon Taylor
   supply chain electronics
Wake Forest, North Carolina

February 6, 2012appended

RFQ. I am searching for a caulk that can be used to seal large weldments prior to powder coating. We used to use a product that worked great but is no longer available from the manufacturer. We have tested several products but have not been able to find anything that is spreadable and can hold up to the heat from the ovens. Is there an easy solution or is this a unique situation?

Andy Michog
- Minneapolis, Minnesota, USA

Hi Andy. We appended your inquiry to a similar thread. As you will read, there are appropriate materials, but the issue can also be one of technique, with several insightful suggestions having been posted. Good luck.


pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
Brick, New Jersey

October 8, 2013

A. Thermobond 3 is used by the powder coating company we use.

Fernando Cendejas
- Anaheim, California, USA


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