Power coating results

[BS Mechanic]

Here are the best pictures I have been able to get of what the surface of my recently power coated frame looks like.  It's not easy to take a picture of a black surface!

Opinions are welcome, what do you think?  Am I expecting too much, or did I just get a bad job done?

Thanks!

[Toystoretom]

I have had things powder coated that came out much nicer than that. If that were a paint job I would say the surface wasn't cleaned properly before spraying, and the results are the "fisheyes" you see everywhere on your frame. I don't know what would cause that during the powdercoating process, but it looks like you had an amature do that, that's not right. The problem with powder coating is that the frame will have to be stripped down to bare metal and it it will have to be redone, a huge job.

[reed]

Bob
I have a lot of power coating done  between five and ten frames a year that's a bad job!
They will have to sand blast the frame and do it again.
Thanks.
Steve.
PS If your frame was clean and very little rust it should turn better than that.
Have a look at Richard GTR frame.

[reed]

Bob
Have a look at Mike Anderson GTR frame in the gallery!
Thanks.
Steve.

[ztnoo]

Overview: http://en.wikipedia.org/wiki/Powder_coating

"There are several advantages of powder coating over conventional liquid coatings:

   1. Powder coatings emit zero or near zero volatile organic compounds (VOC).
   2. Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging.
   3. Powder coating overspray can be recycled and thus it is possible to achieve nearly 100% use of the coating.
   4. Powder coating production lines produce less hazardous waste than conventional liquid coatings.
   5. Capital equipment and operating costs for a powder line are generally less than for conventional liquid lines.
   6. Powder coated items generally have fewer appearance differences between horizontally coated surfaces and vertically coated surfaces than liquid coated items.
   7. A wide range of specialty effects is easily accomplished which would be impossible to achieve with other coating processes.


While powder coatings have many advantages over other coating processes, there are some disadvantages to the technology. While it is relatively easy to apply thick coatings which have smooth, texture-free surfaces, it is not as easy to apply smooth thin films.


The powder coating process involves three basic steps:

   1. Part preparation or the pre-treatment
   2. The powder application
   3. Curing

Part preparation processes and equipment
Removal of oil, soil, lubrication greases, metal oxides, welding scales etc. is essential prior to the powder coating process. It can be done by a variety of chemical and mechanical methods. The selection of the method depends on the size and the material of the part to be powder coated, the type of soil to be removed and the performance requirement of the finished product.

Chemical pre-treatments involve the use of phosphates or chromates in submersion or spray application. These often occur in multiple stages and consist of degreasing, etching, de-smutting, various rinses and the final phosphating or chromating of the substrate. The pre-treatment process both cleans and improves bonding of the powder to the metal. Recent additional processes have been developed that avoid the use of chromates, as these can be toxic to the environment. Titanium zirconium and silanes offer similar performance against corrosion and adhesion of the powder.

Another method of preparing the surface prior to coating is known as abrasive blasting or sandblasting and shot blasting. Blast media and blasting abrasives are used to provide surface texturing and preparation, etching, finishing, and degreasing for products made of wood, plastic, or glass. The most important properties to consider are chemical composition and density; particle shape and size; and impact resistance.

Silicon carbide grit blast media is brittle, sharp, and suitable for grinding metals and low-tensile strength, non-metallic materials. Plastic media blast equipment uses plastic abrasives that are sensitive to substrates such as aluminum, but still suitable for de-coating and surface finishing. Sand blast media uses high-purity crystals that have low-metal content. Glass bead blast media contains glass beads of various sizes.

Cast steel shot or steel grit is used to clean and prepare the surface before coating. Shot blasting recycles the media and is environmentally friendly. This method of preparation is highly efficient on steel parts such as I-beams, angles, pipes, tubes and large fabricated pieces.

Different powder coating applications can require alternative methods of preparation such as abrasive blasting prior to coating. The online consumer market typically offers media blasting services coupled with their coating services at additional costs.

Removing powder coating
Methylene chloride is generally effective at removing powder coating, however most other organic solvents (acetone, thinners, etc.) are completely ineffective. Most recently the suspected human carcinogen methylene chloride is being replaced by benzyl alcohol with great success. Powder coating can also be removed with abrasive blasting. 98% sulfuric acid commercial grade also removes powder coating film.[citation needed] Certain low grade powder coats can be removed with steel wool, though this might be a more labor-intensive process than desired."

[reed]

Bob
Whats the news on your frame,did you take it back.
Thanks.
Steve.

[BS Mechanic]

I took my frame back to the place that did the bad job, but didn't get anything out of them.  Their position is that they did as good a job as could be expected, and that attempting to strip and redo the work would likely result in no improvement, possibly worse. 
I have never found it a good idea to push someone into doing something they don't want to do, it's likely to turn out badly for both parties!

After considering that this place typically does larger more "industrial" coatings, where a good thick coverage is more important than a good finish, I'll mark them down as a bad place to do business, and look elsewhere.

Otherwise my restoration is coming along quite well.  All the bits and pieces have either been restored to new condition, or replaced with NOS parts, thanks in large part to Richard. Last of the painted parts are out getting painted, and I'm sending the last of the smaller items out for chrome tomorrow. 

If I can get the frame redone to a more satisfactory appearance, I'll be ready to start building a bike!

[reed]

Bob
If you can get that frame to me i can get done for you!
Thanks.
Steve.

[Mike Anderson]

Hey Steve,
You beat me to it, I just sent him a message to let him know I have several good powdercoating shops close by. We will see where he is close to. I do not know where he lives. Talk soon.
Later Mike

[reed]

Mike
Bob maybe nearer to you and i know you can help with a good powdercoating shop!
Thanks.
Steve.

[BS Mechanic]

I really appreciate your offers of help with my frame, it's what makes this site so great...the people!!

I'm in east central Iowa (Central City), so I'm quit a ways west of  you.

I'm sure I'll be able to find a decent shop here locally. 
(It will be easier since I know one I can definitely cross off my list of possible choices!)

Thanks again for the offers though!
Bob H.

[reed]

Bob
I have had my Bridgestone GTR frame power coated and i picked up the center stand and swinging arm today and i will email
Pictures to Mike and Richard to post for me it would take to long on my set up  there is only Dial up etc.
Thanks.
Steve.

[BS Mechanic]

Powercoating take II  Frame is back to clean, bare metal again.

I believe I've found a good shop, so I left my frame, brake plates and drums with them this afternoon.  They started out doing work for custom cars, and have now built up a pretty wide ranging list of customers.  They seem to understand the process extremely well, and promised no disappointment with coating quality this time! 

I'm having them clear coat the brake plates and drums also.  I think that will come very close to the original "pastic" coating that was used. 

On clean metal they do a hot water wash, phosphate rinse, then a zinc primer which they half cure before putting on and curing the top coat.  They will use their "medium gloss" black, which looks like a very good match to the original frame paint.  Finished coatings are about 5 mils thick, which sounds about right.  My original job was at least 20-25 mils in many places!  The samples of work they were doing looked perfect.

Proof will be in the finished work, so we'll see how they do!

[reed]

Bob
Good news on your frame it wont be long before your Bridgestone GTR will be on the road.
I have a question, i have new brake drums and brake plates and there is no coating on them.
Thanks.
Steve.

[BS Mechanic]

Steve,
Are the brake plates and drums you have new old stock, as from Richard?  If so, and they are not coated, that may mean that the clear coating was applied at the assembly factory instead of where the parts themselves were made.  It's interesting to try to piece together how things were built in the past.

[reed]

Bob,
Yes nos parts and i agree its is interesting stuff!
Thanks.
Steve.