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How do you prep prior to powdercoating?

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motoguy
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How do you prep prior to powdercoating?

Post by motoguy » Mon Oct 03, 2016 6:32 pm

I'm curious to see what methods you use to prep prior to powdercoating. My oven will be here next week, and I'm looking forward to leaving paintwork in the past. I'm curious what prepwork you guys do prior to powdercoating. I'll initially be coating smaller items (less than 22" square), which can fit in my sandblast cabinet.

I'm planning on cutting using P&O steel. Wipe down with denatured alcohol prior to cutting. Cut, grind/de-dross. Then put in the blast cabinet, just to "etch" the surface, and give some mechanical bite.

Do you guys do something besides blasting? What about phosphating? After sand blasting, what is needed to clean the part? Wipe down good with denatured alcohol, and lint-free rag? My detailed parts tend to tear/snag on a rag, and leave "fuzzies" all over the part. Hit the part with a MAPP gas torch, to burn off the fuzzies? At this point, hang and coat?

Just trying to get my workflow and expectations down.

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Re: How do you prep prior to powdercoating?

Post by littlefatbuddy » Mon Oct 03, 2016 8:49 pm

I do not powder coat but the guy that does mine sandblasts and wipes down with acetone. He just uses blue shop towels and preheats almost every piece.

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Re: How do you prep prior to powdercoating?

Post by Redneck » Mon Oct 03, 2016 10:02 pm

CRS, cut, wire wheel, flap disc as needed to remove remaining dross, wash with degreaser and soft brush, power wash with hot water, phosphate, rinse, dry, powdercoat.

tjenus
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Re: How do you prep prior to powdercoating?

Post by tjenus » Tue Oct 04, 2016 8:04 am

wipe down with wax and grease remover,
sand grind and prep part.
sand blast
hot tank part
rinse
acid wash
rinse
phosphate coat
rinse with hot water
straight to booth, unless its a cast part, then preheat,
if its aluminum I skip the hot tank,
thanks KH
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Bigrhamr
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Re: How do you prep prior to powdercoating?

Post by Bigrhamr » Tue Oct 04, 2016 9:44 am

De-grease
Blast, once blasted handle parts only with clean nitrile or latex gloves.
Blow off with high pressure air
Sometimes wash with DA in a pressurized pump can, closely watching the stream run off tells you if there is blasting dust residue
still on the part.
That gives you a clean part with a good profile. Phosphate will add more corrosion protection.
Wiping a part after blasting just gives you more chances to get lint or other contamination on the part. At this point if there is anything to wipe off consider that you will just be smearing it around anyway.
Keep your blast media clean, never put a part in the cabinet that is not clean.

tjenus
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Re: How do you prep prior to powdercoating?

Post by tjenus » Tue Oct 04, 2016 12:48 pm

Bigrhamr wrote:De-grease
Blast, once blasted handle parts only with clean nitrile or latex gloves.
Blow off with high pressure air
Sometimes wash with DA in a pressurized pump can, closely watching the stream run off tells you if there is blasting dust residue
still on the part.
That gives you a clean part with a good profile. Phosphate will add more corrosion protection.
Wiping a part after blasting just gives you more chances to get lint or other contamination on the part. At this point if there is anything to wipe off consider that you will just be smearing it around anyway.
Keep your blast media clean, never put a part in the cabinet that is not clean.
I agree 99% with you on everything but compressed air, Just need to be carful of oil or water in the air, I couldn't use it because of my type of system, to much oil in system from a rotary screw compressor, other then that spot on, thanks KH
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Redneck
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Re: How do you prep prior to powdercoating?

Post by Redneck » Tue Oct 04, 2016 2:45 pm

tjenus wrote: I agree 99% with you on everything but compressed air, Just need to be carful of oil or water in the air, I couldn't use it because of my type of system, to much oil in system from a rotary screw compressor, other then that spot on, thanks KH
If you have too much oil in your air to blow the part off, how then are you powdercoating?

tjenus
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Re: How do you prep prior to powdercoating?

Post by tjenus » Tue Oct 04, 2016 3:08 pm

Redneck wrote:
tjenus wrote: I agree 99% with you on everything but compressed air, Just need to be carful of oil or water in the air, I couldn't use it because of my type of system, to much oil in system from a rotary screw compressor, other then that spot on, thanks KH
If you have too much oil in your air to blow the part off, how then are you powdercoating?
I run a dedicate oil water separator in the booth, use it just for the guns and my fresh air system, I don't have a system big enough for my whole shop, thanks KH
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Bigrhamr
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Re: How do you prep prior to powdercoating?

Post by Bigrhamr » Tue Oct 04, 2016 3:35 pm

tjenus wrote:
Bigrhamr wrote:De-grease
Blast, once blasted handle parts only with clean nitrile or latex gloves.
Blow off with high pressure air
Sometimes wash with DA in a pressurized pump can, closely watching the stream run off tells you if there is blasting dust residue
still on the part.
That gives you a clean part with a good profile. Phosphate will add more corrosion protection.
Wiping a part after blasting just gives you more chances to get lint or other contamination on the part. At this point if there is anything to wipe off consider that you will just be smearing it around anyway.
Keep your blast media clean, never put a part in the cabinet that is not clean.
I agree 99% with you on everything but compressed air, Just need to be carful of oil or water in the air, I couldn't use it because of my type of system, to much oil in system from a rotary screw compressor, other then that spot on, thanks KH
Definitely,
oil in the air system will ruin your whole day. I run a 40 hp rotary screw and dry/filter everything that goes to blasting, powder and of course the plasma. I monitor the filters, so far no problems with oil as long as the seperator in the compressor gets changed on schedule.
What are you doing for your phosphate process? That is next on my list.

tjenus
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Re: How do you prep prior to powdercoating?

Post by tjenus » Tue Oct 04, 2016 4:23 pm

I have 5 small tanks , Caustic hot tanks, rinse, acid, rinse, phosphate, if the parts are small enough, I use that system and just dunk all the parts, I have a I-Beam above the tanks and a chain hoist, just go down the line rinsing between with hot water, if its to big for that I have a chemical setup on my hot water pressure washer to do the caustic and acid, then a pump sprayer for the phosphate, Just spray on, keep it wet for a few min. then use warm water to rinse off, turns kind of blueish, very faint, have had great luck with this, thanks KH
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Re: How do you prep prior to powdercoating?

Post by AdrianH » Thu Dec 29, 2016 6:42 pm

Hope I am OK posting on the back of this but I need to ask your views.
I am new to powder coating with what is the same as the harbour Freight unit you guys can buy, I have only done some plasma cut outs at the moment and do not have a sandblaster to clean them off.

I basically remove dross with pliers and grinder, then stick the part into a Vibratory tumbler for an hour or so. Then I tend to use a bath of Hydrochloric/Muriatic acid to remove mill scale, then rinse, a final clean off with a rag and acetone before a pre heat, leave to cool and then coating.

I believe there is zinc passivate dip I could use to key the metal, although I seem to have difficulty finding a suitable solution in the UK. So I have two questions, do you think it is worth it for me to try and do you have any links to a solution that I could search for here in the UK.

Many thanks

Adrian
Last edited by AdrianH on Sat Dec 31, 2016 5:38 pm, edited 1 time in total.

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Re: How do you prep prior to powdercoating?

Post by abmetal » Fri Dec 30, 2016 8:37 am

I use a FLAT flap wheel to remove the dross which is minimal, then beadblast. Then it's ready to powdercoat.

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Re: How do you prep prior to powdercoating?

Post by Dana gear » Tue Apr 11, 2017 9:57 pm

We call it blow and go, basic prep and then sand blast then placed on to the hanger assembly roll it through paint booth and then on to the oven.

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Re: How do you prep prior to powdercoating?

Post by gamble » Wed Apr 12, 2017 10:14 am

Flap wheel
DA sander
Wipe down with acetone
But I am by no means a pro
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motoguy
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Re: How do you prep prior to powdercoating?

Post by motoguy » Wed Apr 12, 2017 10:53 am

Recently installed my powder oven and powder booth. Oven is 4x4x6, booth is sized equivalent. However, the only sand blaster I have is my Harbor Freight floor stand model (with Tacoma Company upgrades). Getting a 24"x24" monogram in there requires some Tetris-like maneuvering, sometimes. Anything larger I cannot fit in the blaster at all. I'd like to build a blaster similar in size to the powder oven, but that will be a while.

So, I too am curious about prep and coating. I've run across several people who state they cut, remove dross, flap wheel, wipe with acetone, and coat. This is obviously an appealing idea, since I do everything up to the flap wheel anyway. I'm sure this would be fine for indoor pieces, however I'm curious how outdoor steel parts may fare. Powder should be easier than paint on my end, but I'm also concerned about steel parts rusting if exposed to the weather.

For the 24" and smaller stuff, I can probably fit it in my blaster for a quick hit. Larger than that, blasting is not an option. Then on to the next step.

I've run across the one-step phosphate on Powder365. I'm thinking this stuff, in a bucket w/ a bucket heater (to get up to 140 degrees or so), through an electric sprayer may be a possibility. Or possibly just heat the mixture, then put it in a regular Solo style pump-sprayer (like I use with my Steel F/X patinas). Or, build a dunk-tank of some sort, and just let the pieces sit in there. My understanding is that phosphate can be applied cold, it just takes longer.

Those of you who do minimal prep, what kind of outdoor longevity are you seeing? I'd like to spend the minimal time (and space) on prep, but I want it to last. Then again, it's not going to be exposed to 24x7 salt spray, either.
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Re: How do you prep prior to powdercoating?

Post by sawdust1 » Wed Apr 12, 2017 11:14 am

Pieces I cannot get into the sandblast cabinet I scuff lightly with an old flap disc or sanding disc. I wash everything with acid to get rid of the millscale first, even pieces to be sandblasted. I use an old disc so the roughed metal is not so gouged it shows through the powder.

I have a couple different size plastic under the bed kind of storage tubs that I use for acid bath. Really big pieces I gear up and wipe with straight Muriatic.

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Re: How do you prep prior to powdercoating?

Post by davek0974 » Wed Apr 12, 2017 4:36 pm

when blasting, what is a good media to give a key to smooth metal?

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Re: How do you prep prior to powdercoating?

Post by MustangMat » Wed Apr 12, 2017 4:53 pm

We have a single stage wash. We high pressure rinse the parts (fresh sheet metal parts) with a chemical water mix. I have to see what it's exactly called. Then we rinse with water. Put in oven to dry and take it out and then powder it

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Re: How do you prep prior to powdercoating?

Post by adbuch » Sat May 14, 2022 4:58 pm

davek0974 wrote:
Wed Apr 12, 2017 4:36 pm
when blasting, what is a good media to give a key to smooth metal?
My local powder coater uses steel shot for blasting. Leaves a very smooth clean surface for coating resulting in a superior looking job.
David

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Re: How do you prep prior to powdercoating?

Post by 34by151 » Sat May 14, 2022 6:08 pm

Clean with hot water pressure washer (small amount of wax and grease remover mixed into water)
Dry off
Coat

Some parts also need a sandblast after washing. I rewash and dry these

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Re: How do you prep prior to powdercoating?

Post by adbuch » Sat May 14, 2022 6:22 pm

34by151 wrote:
Sat May 14, 2022 6:08 pm
Clean with hot water pressure washer (small amount of wax and grease remover mixed into water)
Dry off
Coat

Some parts also need a sandblast after washing. I rewash and dry these
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Re: How do you prep prior to powdercoating?

Post by plasmanewbie » Tue May 17, 2022 10:36 am

I like to sandblast everything before I powder coat. I have found that to promote amazing adhesion and prevents the coating from chipping off easily.

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Re: How do you prep prior to powdercoating?

Post by adbuch » Tue May 17, 2022 8:15 pm

Yes - I would imagine that the rougher surface from sand blasting would promote better adhesion than blasting with the steel shot.
David

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