Newbie questions!

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jeffjam
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Newbie questions!

Post by jeffjam » Sat Jun 27, 2020 2:43 am

Hello,

I'm new to applying powder coating myself but have had it done numerous times in the past and have an idea of how it works.

I have some newbie questions that i would appreciate any guidance on.

I would like to change the color on a set of brand new wheels which are powder coated from factory. I am changing from a matte gunmetal color to a satin bronze.
1. Although wheels are new do I still need to remove all existing powder coating back to bare metal?
2. When second and third coating do I bake in-between coats for a shorter period of time?
3. If I do this in an automotive spray booth, do I have the exhaust fans on or will this take away the powder when spraying?
4. Could an automotive paint heat lamp be used for the baking or does this require an oven?

Just some basic questions to get me started, thanks in advance for any advice!

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Jay V
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Re: Newbie questions!

Post by Jay V » Sat Jun 27, 2020 12:50 pm

jeffjam wrote:
Sat Jun 27, 2020 2:43 am
Hello,

I'm new to applying powder coating myself but have had it done numerous times in the past and have an idea of how it works.

I have some newbie questions that i would appreciate any guidance on.

I would like to change the color on a set of brand new wheels which are powder coated from factory. I am changing from a matte gunmetal color to a satin bronze.
1. Although wheels are new do I still need to remove all existing powder coating back to bare metal?
2. When second and third coating do I bake in-between coats for a shorter period of time?
3. If I do this in an automotive spray booth, do I have the exhaust fans on or will this take away the powder when spraying?
4. Could an automotive paint heat lamp be used for the baking or does this require an oven?


Just some basic questions to get me started, thanks in advance for any advice!
1. Yes.
2. Yes - partial cure. Take the part up to 350F briefly, then let cool.
3. You want an exhaust fan to remove the powder, but powder may screw-up wet-paint filters.
4. No. You need to get to 375F and stay there for approx 15 minutes. You need the proper oven.

Without the proper equipment - chemical stripper, gun, booth, and oven - you are only going to mess-up the wheels.

jeffjam
Posts: 3
Joined: Sat Jun 27, 2020 2:28 am
My Location: kingston

Re: Newbie questions!

Post by jeffjam » Sun Jun 28, 2020 12:04 am

Thank you for the advice!

Brandon.spence
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Re: Newbie questions!

Post by Brandon.spence » Thu Jul 09, 2020 12:29 am

1: Not necessarily. You can powder coat over an existing coat if you are considering durability as an important element for the coating. You can also consider this if you would like to make some cost-effectiveness. But these are subjective to certain factors like the ability to tolerate high temperature, if you are ok with a thick film fluid, the existing coat is not so thick also check with the powder manufacturer regarding its specs and performance.

2:I think you will need to have some professional powder coating experience for that or at least use a professional tool. Mid or professional level guns have the feature of adjustable KVs. During multiple coatings, you have to ensure that the current coating KV is 50% less than the previous one. For example, if the first coating was done at 60KV then the next coating must be less than or equal to 30KV maximum. Or else there is a chance of getting baked. You need not buy this equipment if it's a one time purpose you can rent them. I suggest you to seek the help from the professionals if you are an amateur.

3: All automotive spray booths have the exhaust fans on. This is for proper ventilation. This helps in clearing the vapor-laden air while make-up air enters from the top of the booth. The amount of air a paint booth exhausts will depend on the style of the paint booth. Hence the problem of powders being taken away depends upon the style of spray booth used.

4: The baking is normally done in a special oven; the coating has to be exposed to a temperature range of 350 to 400 degrees Fahrenheit (160 to 210 degrees Celsius) for 20 minutes. If you are planning to use your home oven, make sure you never use it to cook food after this. Infrared heat lamps bake from the outside and require less time. Heating the metal is unnecessary to cure or bake the powder. This is more of an eco-friendly way and generally used for bigger parts.
This is a delicate job. Make sure you use proper equipment. Cheers.

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Jay V
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Re: Newbie questions!

Post by Jay V » Thu Jul 09, 2020 8:59 am

Brandon.spence wrote:
Thu Jul 09, 2020 12:29 am
1: Not necessarily. You can powder coat over an existing coat if you are considering durability as an important element for the coating. You can also consider this if you would like to make some cost-effectiveness. But these are subjective to certain factors like the ability to tolerate high temperature, if you are ok with a thick film fluid, the existing coat is not so thick also check with the powder manufacturer regarding its specs and performance.

2:I think you will need to have some professional powder coating experience for that or at least use a professional tool. Mid or professional level guns have the feature of adjustable KVs. During multiple coatings, you have to ensure that the current coating KV is 50% less than the previous one. For example, if the first coating was done at 60KV then the next coating must be less than or equal to 30KV maximum. Or else there is a chance of getting baked. You need not buy this equipment if it's a one time purpose you can rent them. I suggest you to seek the help from the professionals if you are an amateur.

3: All automotive spray booths have the exhaust fans on. This is for proper ventilation. This helps in clearing the vapor-laden air while make-up air enters from the top of the booth. The amount of air a paint booth exhausts will depend on the style of the paint booth. Hence the problem of powders being taken away depends upon the style of spray booth used.

4: The baking is normally done in a special oven; the coating has to be exposed to a temperature range of 350 to 400 degrees Fahrenheit (160 to 210 degrees Celsius) for 20 minutes. If you are planning to use your home oven, make sure you never use it to cook food after this. Infrared heat lamps bake from the outside and require less time. Heating the metal is unnecessary to cure or bake the powder. This is more of an eco-friendly way and generally used for bigger parts.
This is a delicate job. Make sure you use proper equipment. Cheers.
A couple things...

#1 - Coating OVER an existing coating is hack.

These days, most quality wheels have a TON of material on them. I've measured anywhere from 15 to 25 MILS on an OEM wheel. No way can you do a quality job coating over that. You will need to heat the wheel up and toss a ton of powder at it, and it will look like crap. I repaired a wheel done that way a while ago. Local coater did it - and it was on a $100,000+ used car (Audi R8)! Big chip of powder fell off when the previous owner tagged a curb. The wheel had not been touched before coating, it was bright shiny silver under the powder. Manufacturers typically state thickness in the range of 2.5 to 3.5 MILS as optimum.

#4 - IR lamps aren't going to do a proper job of curing the powder. The part is going to suck up all the heat until it reaches a stabilized temp. You need the entire part to be at the proper temp to get correct curing.

There are special coatings that are designed for curing in that manner, but I don't think you are going to get good results with small lamps and standard powder.

It may work on an Industrial scale in a controlled environment, but anything less is going to be a fail.

Brandon.spence
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My Location: Toronto

Re: Newbie questions!

Post by Brandon.spence » Mon Jul 13, 2020 2:07 am

Hey Jay! Yeah! I agree with that. It's true.

jeffjam
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Joined: Sat Jun 27, 2020 2:28 am
My Location: kingston

Re: Newbie questions!

Post by jeffjam » Mon Aug 03, 2020 8:50 pm

Thanks for alL the advice. I went ahead and sandblasted the wheels and tried to powder coat one of them today. I am using an eastwood dual voltage gun that I just bought new. I had a 8’ ground rod installed and I ran a wire from that to the wheel as well as grounded wheel with wire that comes out of control box of the eastwood gun. I dont know whats wrong but i cant seem to get the powder to adhere to the wheel. It seems something isnt right. The gun is giving off voltage because i did touch the tip by accident and learnt my lesson lol.
Any suggestions on what i may be doing incorrect???

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Jay V
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Re: Newbie questions!

Post by Jay V » Tue Aug 04, 2020 9:29 am

Check your ground anyway. Use an Ohm meter on the part and on a known ground.

I had an issue a few years ago where I lost my ground. I was (am) using a rotating hook, and it gets a small amount of powder inside it eventually and the pressure bonds it to the metal, insulating it.

I cured that by running a wire from the rod it was hanging from around the hook and onto the wire, bypassing the hook. Problem cured.

If I need to hang a part in a questionable manner (for grounding) I will check it with an Ohm meter, touching the part and somewhere higher up on the wire or the side of the booth to confirm the ground is good.

Sometimes you are surprised and need to make changes.

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