Welding Tips and Tricks

So, I am working on a small project building a new support frame for our spa cover. I removed all the mill scale before starting to work because I knew it would be easier to do before I got started simply because it will be awkward after the frame is complete.

So, today I noticed a few spots that have already started to rust, and now I'm wondering if I should have just left the mill scale on and then painted over it.

So, what do YOU do? Do YOU paint over it or strip it all off and then paint on bare metal?

If YOU pain over the mill scale, are there any tips, or things to be aware of when choosing your paint, or do you just shake a can of metal spray paint and go to town?

Keep in mind that this will be a high humidity situation, so make sure to let us know if you use different kinds of paint for differing humidity expectations.

And yes, I realize I'm asking a little late for this project, but I'm expecting more in the future.

Thanks,

Bill

Anytime I paint a project I just use spray cans just a coat of primer and then what ever color you want it it seems to work just fine for me

High humidity situation combined with steel then personally I'd have the material zinc plated in some shape or form before any paint is applied.

Highest level of corrosion protection will be from a hot-dip zinc plating process (thickest zinc layer deposited), but the heat of the process can induce some warpage in structures and all tubular parts must have openings in them or they will rupture from the internal pressure buildup. Other options would be electroplating/galvanising for parts or zinc spray transfer for a built-up structure. That gives you a sacrificial galvanic bottom layer which will stall the rust process for a long time and stops 'creep' of the rust under the paint.

I always go down to bare/clean metal, rough up the surface for a good 'key' and then use a good etching epoxy primer as a base. Helps if you get one that has some anti corrosion additives as well. Then build up with several layers of paint over this to seal everything completely.

Zinc plating and then a nice thick powdercoat is usually the most resilient solution, but not always usable for larger structures.

There are also some more specialised moisture curing or 2-part epoxy coatings which will form a very durable and hard layer, but these are sometimes harder to obtain or have their own application peculiarites. I have had good results with POR-15 products though, but there are others too.

Bye, Arno.

First and foremost. What's it for ?

Even the best paint job will never be perfect, especially in a high moisture area like a spa surround. Removing the mill scale isnt the really a drama, more adding a little more protection. The way to do this with paint is with a zinc rich primer, or cold gal, as we call it in Aus. And a rust protecting top coat like the kill rust system.

Mick

If you remove the mill scale prior to working it can flash rust the same day in humid climates.
If this is an issue you need to use a weld through primer, or just prime it and grind off the primer where you are about to weld.
Standard paint prep when done building and welding.

The company that sold us our replacement spa cover told us that it "was strong enough to stand on"... well after we received it the center started to bow down and we were told it would be replaced... time went on, promises were made, then calls stopped be returned, e-mails never responded to... basically it has been a waste of time and money and I'll probably be filing a small claims suit against them soon.

In the meantime, I realized that the issue is that there is not a metal frame in the cover which is pretty standard. Based on the fact that the replacement didn't come quickly, I think that they chinced out on me and ordered a cheaper version that did not have a frame... so... I'm making a frame and plan to route out a pocket for it in the foam and then seal it in with spray foam and re-wrap it in plastic.

Unfortunately, I'm disabled and can only work out in the garage for about 2-3 hours every other day so my projects take a long time to complete. It figured it would be easier to remove all the mill scale before the frame was complete because it is about 84 inches by 32 inches. I got slowed down quite a bit because of a bunch of physical testing to requalify for disability and start the SSDI process and basically my eval says I can't even do a desk job (which is what I had), so since I started I noticed that a little bit of rust has crept in.

I had originally planned to spray it with rustoleum, but now I'm thinking that I might want to do something more. I don't really have any painting experience other than painting the inside of my house so I thought I'd ask for some advice here.

I took a 33% paycut due to the disability, so anything I do will be basic auto or home improvement store store stuff, but I do have a Wagner power sprayer with a detail sprayer if that might get me a better solution.

Just figured I'd ask here to get some advice since I should be done with the first frame in the next couple of days after I recover from the stroke that taxes are giving me.

Thanks

Bill

tradetek,
I have about 10 years of industrial painting experience and will say that unless you step up to some of the industrial paints, you will almost always have paint adhesion issues, and even with some of the industrial stuff. Polane is a very good compromise for what you are wanting, but Its not cheap in any way shape of form.
While I would recommend cold galvanize or hot dip galvanize if it were a fence or bollard, I would not use it for any submersion use or high humidity. What most don't realize is if you submerge galvanizing, epoxy and powder coating, they WILL peal off over a short period of time. Another thing to consider is if you use a cold galvanize, you have to make sure you use a top coat or primer that is compatible with it or again it will peel off.
Powder coat is actually porous and will "suck" of draw in the moisture allowing the metal to rust and lift the coating off, again over time.
You mentioned that it will be covered or sealed off. I would assume this to mean sealed off from the moisture, as best as you can. IF it is sealed off and considering your budget, I would recommend a etching primer and Rust-oleum high gloss finish, this will most likely last for 5 years.
Anyway just my opinion, take it for what its worth.
-Jonathan

Reading the advert comment, "strong enough to stand on", it occurred to me, do you ever need to stand on it? Replace it with sch 80 CPVC and be done...

Steve S

Otto Nobedder wrote:Reading the advert comment, "strong enough to stand on", it occurred to me, do you ever need to stand on it? Replace it with sch 80 CPVC and be done...

Steve S

That is a good thought.
-Jonathan

Maybe someone said "Clean the spa.....and step on it...."

@Steve - PVC in a size that would actually fit inside the cover is not stiff enough. The cover has to be able to support up to 2 feet of snow. It is standard for a good quality spa cover to have a metal frame in it to support the weight of snow and pooling water from heavy rains.

@Jonathan - Thanks for the info. Do you think a layer of Plastidip on top of the Rustoleum would help anything?

@Mike - Yeah, I should have checked to make sure he wasn't crossing his fingers behind his back

Bill

tradetek wrote:
@Jonathan - Thanks for the info. Do you think a layer of Plastidip on top of the Rustoleum would help anything?

Bill

Bill,
Personally, once you get the final coat of paint on you will be good to go. One thing I would be concerned about is the paint will still outgas and cure for up to 30 days after application and I would think the Plastidip will inhibit this process causing adhesion problems.
I have applied paint over primer way before the primer was done curing and you could actually take your finger and smear the paint right off. Not saying this will happen to you since the paint in cans generally cures faster then other paints.
2 cents.
-Jonathan

Superiorwelding wrote:One thing I would be concerned about is the paint will still outgas and cure for up to 30 days after application

Didn't realize that. How long would you recommend waiting to paint over rattle can primer?

And how long would you recommend waiting to let Rustoleum cure before putting into a foam "encasement"?

Thanks,

Bill

tradetek wrote:

Superiorwelding wrote:One thing I would be concerned about is the paint will still outgas and cure for up to 30 days after application

Didn't realize that. How long would you recommend waiting to paint over rattle can primer?

And how long would you recommend waiting to let Rustoleum cure before putting into a foam "encasement"?

Thanks,

Bill

Bill,
The paint can you will purchase should tell you the time to touch, to handle, recoat and cure time. The touch means just that, you can touch it but not handle it yet. The recoat it the window you must recoat it in and if it exceeds this recoat time, you must wait until the cure time elapsed before a second coat is applied. The cure time is when all outgassing and curing is supposed to be done. Once you reach the cure time you are good for the next coat. This process can be sped up if it were baked or the tubing was heated first and then paint of primer applied. Do not heat up the part to much. If you apply paint or primer and it quickly bubbles, it is way to hot.
For the foam encasement, I would wait until the cure time has elapsed and then you will be fine.
You have to realize that most don't follow these guidelines when it comes to paint cure times and most of the time it comes out fine. I am just very picky when it comes to paint.
-Jonathan

Thanks for the extra info Jonathan, I doubt that I would have realized that the recoat "window" was just that, an open and close window before you have to wait for it to cure.

Really appreciate the extra help.

Have a good weekend,

Bill