Galvanized Skin INSIDE of the oven?

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Joe Jones
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Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

So I am designing my powder coat over now. I was SURE I could build it for less than a commercial unit :lol: :Wow :Sad

I am going to build one anyway, because I cannot find an oven that is set up the way I want it.

The oven will have two banks of heating elements. I can switch to the upper bank and raise the internal platform, which will give me a smaller oven, or remove the platform and use the lower bank of elements to heat the larger volume.

The walls, door and ceiling will all be 6" steel studs with rock wool insulation. It will sit on the concrete floor. I am not planning to have an insulated floor, UNLESS it is particularly beneficial.

I have the design made, with two banks of burners and a center platform that will allow me to slip it onto a support along the walls and reduce the size of the oven for smaller parts.

Everything is looking good, but now I am pricing STEEL. :Wow

Holy friggin' COW! I was going to wrap this in 20 gauge stainless inside and out. The best price I can find is $362.00 per 4x8 sheet. :Wow

At 12 sheets, that is a $4,000.00 "pretty" that I just cannot justify.

I HAVE a pallet of 16 gauge cold roll steel 4x10 sheets. I suppose I could use those. I rarely make anything out of 16 gauge steel.

So I got to calling around. I now understand why everyone's powder coat ovens are rusty inside. It costs to damned much money to give the interior any kind of finish!

I have a friend who has an HVAC business. He says he can get me 4x8 sheets of galvanized steel for $46.00 per sheet. The PRICE is awesome, but the $64,000.00 question is ...

Is it SAFE to use galvanized steel in a powder coat oven heated by electric elements?

He thinks it might melt at 400 degrees.

I will spend a couple of weeks building the frame, and the controller, and installing the elements, lights, fans, ducting, and so forth. THEN I have to figure out the skin.

Tell me this ... Is there any problem with using FIRE RATED 5/8" DRYWALL instead of steel for the skin inside? Does it HAVE TO BE metal? Wouldn't a double layer of 5/8" drywall work?

My other thought was, since the insulation is doing the job of containing the heat, can I use expanded metal inside? It would protect the insulation, but it is not a SOLID skin. It would give me a great option to insert rods across the openings to hang parts though.

I even thought about using tempered GLASS. Believe it or not, you can get large sheets of tempered glass for FREE! I did this in COMMIEfornia, taking the thick tempered glass panels out of sliding glass door frames to make solar heater covers. The glass shops GIVE them away, as people replace the older sliding glass doors with the new double panel gas filled vinyl framed stuff. Then they don't have to smash the glass into bins, and deal with all of that. As a bonus, I got to recycle the old aluminum frames!

The drawback of glass is that you have to work with the dimensions of the glass panels, as tempered glass cannot be cut. Also, you cannot drill through it to mount brackets or whatever.

Aluminum is out of the question, and I am assuming that aluminum would be self-defeating, as it would PASS the heat through to the insulation, right?

I am beginning to think I should call a tile man and have the whole thing done in ceramic tile! :HaHa Hey, it works on the Space Shuttle!

Crazy times ....

Joe


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Re: Galvanized Skin INSIDE of the oven?

Post by SegoMan DeSigns »

Joe,

That is the 392* question, others have stated that they use it with no problems yet the "so Called Experts" say it starts to off gas at 392*, Ask your sheet metal man if he can get aluminized metal for the interior and and save the cheaper galvanized for the outer skin.

Article:
https://galvanizeit.org/knowledgebase/a ... mperatures
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Re: Galvanized Skin INSIDE of the oven?

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Dupe / delete
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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

Aluminized metal? OK I will talk to him about it I’ve I don’t know if they use that type of metal in the HVAC business.
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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

Aluminized metal? OK I will talk to him about it I’ve I don’t know if they use that type of metal in the HVAC business.
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Re: Galvanized Skin INSIDE of the oven?

Post by djreiswig »

How about concrete backer board? Not sure about the temperatures, but I think they use it around fireplaces.
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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

djreiswig wrote: Fri Mar 04, 2022 4:53 pm How about concrete backer board? Not sure about the temperatures, but I think they use it around fireplaces.
I just got back from Lowe's. We looked at the fire rating for 5/8" "Fire Rated" drywall, and the concrete backing board, and a lot of other materials. Everything has about a one hour fire rating. This means it will FAIL after one hour. That will not work for an oven that is brought up to temperature repeatedly.

I started thinking about alternate sources for metal. I know that BMW motorcycle USED TO BE shipped in a metal tube frame, with 24 gauge sheet metal on the top and both sides of each crate, connected by screws into the metal tubing. In COMMIEfornia, I collected a 'YUGE amount of sheet metal panels, but of course, I had not yet "found" PlasmaCam, and I was only viewing the metal as salvage price steel. "Metal Art" was not a part of my life back then.

I will contact the various dealerships tomorrow and see if any motorcycle, quad, ATV, watercraft etc. manufacturers are still using sheet metal to protect their merchandise. The motorcycle shops would unpack the new vehicles and stack the tube frames and sheets of metal for the local guy to take to the recyclers. MAYBE this is still the case ...

A guy at Lowe's suggested I pick up an old METAL U-Haul truck box. They are found here and there. All I would need to do is replace the roll up door with swing doors, and insulate the interior. This would be much larger than the oven I planned, but that might be something to think about for the next oven. After all, it is already a large METAL box with an opening at one end, and a floor too. It wouldn't require a lot to convert one into an oven. Alas, I don't have 3-Phase power to even attempt that, and I am not ready to dive into propane just yet.

In other news, I may have told you that I do not have a memory. Well .., apparently at some time in the past, I purchased a boat load of steel. I found a pallet of 16 ga. hot roll steel that I completely forgot about.

I went out to the FrankenBarn to look at what IF ANYTHING is out there that I could use, and WOW! There they are! 30 SHEETS of 4x10 hot roll 16 gauge steel! 20 sheets of 14 gauge cold roll on top of them, and ten sheets of 12 gauge cold roll beneath them ... all FORGOTTEN about. There are several 16 ga. cold roll 4x10 sheets as well, but not enough to do the whole oven and I don't want to mix-n-match.

There is also another pallet of 4x8 14 gauge stainless steel ... I am guessing 16 sheets ... all forgotten about. They were all covered by a tarp. I thought that tarp covered a stack of EMPTY pallets, as the whole tarp became a catch-all for junk! I bought this steel at a great price in 2018, so it would be beneficial to use them, since I would not need to buy MORE steel at today's high prices.
Replacing them later on will be VERY 'Spensive, Lucy! :Wow

Now I have to decide whether I will EVER use this 16 gauge stuff for metal art, or if I should just sacrifice 10 sheets of it for the oven skins and be glad I bought early at a relatively low price by today's standards. :roll:

So I guess there is nothing to stop me now. I will begin assembling the frame tomorrow (maybe) and I have to figure out how to put that controller together. This is going to come together much easier that I thought.

Joe
OVEN CONCEPT SKETCHUP.jpg


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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

This looks like the final design. Not all of the small pieces have been drawn in, but I will add them when I build it.

Joe

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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

So I have decided to use the 16 gauge steel for the inside and outside of the oven. I have it, so why not use it?

Can a powder coated part be reheated time and time again in an oven?

Since the sheet metal is not stainless steel, and I cannot use galvanized metal for the interior, I am thinking of building the three walls, the door and the ceiling panels, and the center shelf/divider unit and then disassembling the completed oven. I would then send out the assembled panels to a powder coat company near me that can handle panels that size. Then the oven would be reassembled.

Is that a good idea, or a bad idea?

I know, it will cost a King's ransom, but I just don't want a big, rusty metal box in my shop. I suppose I could paint it with high temp spray paint, like the stuff they use on bar-b-que grills and fireplace screens ...

Can you suggest another surface coating that can handle the interior temps and NOT emit deadly gasses, or melt in the heat, or otherwise FAIL in a short time? CHROME PLATING? :lol: :shock:

Tomorrow is if-y. There is a tornado watch until 8:000 AM in effect now. I have a new THERMAL camera called the FLIR PRO that attaches tot he bottom of my iPhone. I guess I will go outside and see how it presents the night weather in thermal imaging.

If the weather cooperates, I will go out tot he shop later THIS morning and begin building the oven. It is 2:02 AM now.

Joe


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Re: Galvanized Skin INSIDE of the oven?

Post by 34by151 »

Gal steel is fine for the inside.

Yes you can reheat a powder coated part, in fact you do this when applying a second colour or a clear coat.
Somthing I do often on calipers and valve covers wher you have a differnt colour on the raised lettering
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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

OK I am curious about your comment that you can use galvanized steel inside of a powder coat oven. I am receiving all kinds of warnings saying that you cannot do this because the oven admits dangerous gases from the zinc coating. I have a source for galvanized metal at $46 per sheet and I would rather use that than my 16 gauge steel sheets but I still want the oven to come out sturdy and Visually appealing. I know it doesn’t make any difference if the sides droop or if the door sags, but I do not want an oven that looks like it was built by Cub Scouts on a camping weekend. So I may go ahead and use that 16 gauge steel anyway because I know that it is more rigid and less prone to bending and warpage than the very thin metals used in the HVAC business.

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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

How do you do a different color on raised lettering? Do you manually mask off the other areas or do you use some kind of a spray mask and an X-Acto knife to expose the areas that receive the different color? I am jumping into this with both feet and quite honestly I don’t know anything about powder coating so I’m sure I am going to screw up a lot of things before I produce anything that pleases me. But I am open to any suggestions or advice from people in the know!

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Re: Galvanized Skin INSIDE of the oven?

Post by 34by151 »

Joe Jones wrote: Mon Mar 07, 2022 5:20 am OK I am curious about your comment that you can use galvanized steel inside of a powder coat oven. I am receiving all kinds of warnings saying that you cannot do this because the oven admits dangerous gases from the zinc coating. I have a source for galvanized metal at $46 per sheet and I would rather use that than my 16 gauge steel sheets but I still want the oven to come out sturdy and Visually appealing. I know it doesn’t make any difference if the sides droop or if the door sags, but I do not want an oven that looks like it was built by Cub Scouts on a camping weekend. So I may go ahead and use that 16 gauge steel anyway because I know that it is more rigid and less prone to bending and warpage than the very thin metals used in the HVAC business.

Joe
take a look at the pics I posted in the other thread of my oven
The mesh is gal as is the side panels
The rear panel is zinc sheet

The marks on the back panel are notfrom heat.It was an old sheet that had a rusty plain steel sheet on top. Its discoloured from the other sheet aand water. I used it in the oven because I couldnot use it for a customer job.

All the inside sheets are 3mm thick

Also remember waht I old you about venting

Use what you have
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Re: Galvanized Skin INSIDE of the oven?

Post by 34by151 »

Joe Jones wrote: Mon Mar 07, 2022 5:22 am How do you do a different color on raised lettering? Do you manually mask off the other areas or do you use some kind of a spray mask and an X-Acto knife to expose the areas that receive the different color? I am jumping into this with both feet and quite honestly I don’t know anything about powder coating so I’m sure I am going to screw up a lot of things before I produce anything that pleases me. But I am open to any suggestions or advice from people in the know!

Joe
It depends on the product
For valve covers I just powder coat them as normal and cover the whole thing
After it comes out of the oven and cools
I mask off the raised letters with heat tape putting a border around the letters and abut 20mm beyond.
This leaves the letters exposed
I dont bother masking up the rest ove the valve cover
I then apply powder using a lower KV setting than the first coat
I then put a box over the masked off area and low the excess powder off (outside the masked area)
Then cook it again

Its also common to apply a full second coat using clear powder

Ive also done a few pearl powders with some flake added
Ive done this over a white or grey powder
Then a third clear coat

If your donig this king of stuff a base kepps you final colour consistant but it pays to do a few base colour tests to check your final results.
Keep these test as swatches for another day.

You can also try mask off the second colour, cook, cool, mask the first colour, cook and cool
I dont like this way because its super hard to mask off the first color perfectly and vey time consuming.
If you leave a gap it start again time
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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

Thank you for all of this great info.

So, if I ^%&* up a piece, how is the powder coat REMOVED to try again? A sandblaster? Or acetone? or ???

Joe


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Re: Galvanized Skin INSIDE of the oven?

Post by djreiswig »

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Re: Galvanized Skin INSIDE of the oven?

Post by Joe Jones »

djreiswig wrote: Mon Mar 07, 2022 1:26 pm viewtopic.php?f=82&t=33503
THANK YOU!!!

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Re: Galvanized Skin INSIDE of the oven?

Post by djreiswig »

I don't powder coat, I just remember reading that post a few days ago. Hopefully it works for you.
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