The Best Way to Paint Galvanized Metal

Painting galvanized metal requires some preparation to ensure proper adhesion and durability. Galvanized metal has a zinc coating to protect it from corrosion, but this coating can make it challenging for paint to adhere. Here's the best process:

1. Clean the Surface

  • Remove dirt and grease: Use a degreaser or soapy water to remove any oils, dirt, or grease from the surface. Rinse thoroughly and allow it to dry.

  • Eliminate white rust: If there is white rust (a chalky residue from the zinc), scrub it off with a wire brush or fine-grit sandpaper.

2. Scuff the Surface

  • Use fine sandpaper (120–150 grit) or a scuff pad to lightly roughen the surface. This helps the primer and paint adhere better.

  • Wipe down the surface with a clean, damp cloth to remove sanding dust.

3. Choose the Right Primer

  • Use a primer specifically designed for galvanized metal, such as a zinc-rich or self-etching primer. These primers adhere well to zinc-coated surfaces and create a good base for paint.

  • Apply the primer in thin, even coats according to the manufacturer’s instructions. Allow it to dry completely.

4. Select the Proper Paint

  • Opt for an acrylic latex paint or a paint specifically formulated for galvanized metal. Avoid alkyd- or oil-based paints unless they are explicitly labeled for galvanized surfaces, as these can react poorly with the zinc coating.

5. Paint Application

  • Apply the paint using a brush, roller, or spray, depending on the size and shape of the surface.

  • Use thin, even coats and let each coat dry completely before applying the next one. Typically, two coats are sufficient for full coverage.

6. Cure and Protect

  • Allow the paint to cure fully before subjecting the surface to heavy use or outdoor elements.

  • For additional protection, you can apply a clear sealant or topcoat if needed.

Tips:

  • New galvanized metal: If the metal is newly galvanized, it may have a shiny surface that makes adhesion difficult. Let it weather for a few weeks or use a vinegar solution (1:1 vinegar and water) to etch the surface before priming.

  • Test adhesion: Before painting a large area, test the primer and paint on a small, inconspicuous spot to ensure they adhere well.

Following these steps will ensure your painted galvanized metal is durable and looks great for years.

Custom One Inch Lined Plenum Boxes and Plenum Sleeves

Depending on the job, commercial or residential, there may be a need for fiber glass acoustical lining on the inside of the duct work. Duct liner, in it’s simplest form, is there to help reduce noise and provide a minimal R-value—much less than duct wrap—to provide more consistent temperatures and energy efficiency.

K&E Sheet Metal’s morning was full of duct liner, one inch thick to be exact. The thickness can range from 1/2” to 2”. Our shop mostly deals with half-inch and one-inch. Occasionally, we will get a spec (specification) for 1 1/2” or 2”, but it’s rare for the size jobs—commercial vs. Industrial— we fabricate for. In future, as the shop grows, that could change.

The liner is cut to size, adhered to the metal with glue, and then secured with corresponding weld pins.

Plenum Sleeves with liner glued; waiting for pins to be welded down.

Plenum Sleeves with liner glued; waiting for pins to be welded down.

Plenums and Sleeves in multiple stages of the lining process

Plenums and Sleeves in multiple stages of the lining process

Steve finishing up weld pinning some plenum sleeves

Steve finishing up weld pinning some plenum sleeves

Joe placing pins for the next step

Joe placing pins for the next step

Finished and ready for pickup

Finished and ready for pickup



Square to Round Monday

Happy Monday! The humidity has arrived in the fabrication shop, as the rains continue here in the Northeast. The floors are coated with a perfect glaze of condensation from the annoying Spring weather patterns. Rain is getting tiresome. Frustrating, but not something to get worked up over. Air conditioning to the rescue!

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We move on. HVAC sheet metal fabrication stops for no weather! The square to rounds must go on!

We are busy and the name of the game today is square to round fabrication. Our shop is limited in the fact that we don’t currently have a spot welder for assembling our square to round fittings. We rivet them. Why not weld? Valid Question. One that many of you fabricators may be asking.

Truth be told, I’ve had different spot welders over the years and have never been thrilled with the results. Collars were continually popping off in the field, making it harder for our customers to get their job done efficiently. So we began riveting, which does take longer, but there is no worrying about failure in the field.

I am aware that a water cooled spot welder would be the way to go. However, it’s just not in the budget at this time. We invested heavily in equipment over the last few years and the focus is on managing that debt. We will get there.

The picture below shows multiple flat stock body patterns of square to round duct fittings after being cut on the plasma table. They are marked to start the bending process.

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Collars for the round portion of the fittings have been built, ready for installation after the guys have assembled the main body of the custom fittings. We usually fabricate the collars first so they are ready to go!

Custom Collars for Square to Rounds

Custom Collars for Square to Rounds

We had a minor issue with the hand beader for the square to rounds. Below, Steve is working diligently to fix the problem.

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We use the manual bead roller to crimp the top—the round end—of the fitting body. The crimp helps to make easier the installation of the collar on the fitting. We then switch out the crimping dyes for the bead dye, which helps to secure the collar to the square to round body. We finish the job with a few rivets.

Crimping

Crimping

Final Bead with Rivets

Final Bead with Rivets

We are currently fabricating an order of 75 square to rounds. They take time and we want to make sure each one is done to the best of our ability. Occasionally, that means sacrificing some speed. I think the trade-off is worth it.

Next on the docket…Custom plenum drops for a couple rooftop heating and cooling units!! Joe is starting that process this afternoon. Sheet number one has finished cutting; next we clear the table, cut the remnants for recycling and use the scrap for other items in the shop. Possibly another square to round!

Joe clearing the plasma table.

Joe clearing the plasma table.

Sheet Metal Cutting Tools: Straight and Bulldog Tin Snips

Why are my cuts coming out so jagged!? Why don't these snips cut a radius well? Why do all of my long cuts A.) Take so long and B.) Have all these little notches every inch or so?

You may or may not have asked yourself these questions or many others while hacking through a piece of tin. 

I've had all these frustrations over the course of my career and some of those issues come down to experience cutting with any kind of tin snip by hand. However, another answer could be that you may be using the wrong snips for the job. One size does not fit all when it comes to sheet metal cutting tools. 

The one tool that I would have gold plated and mounted on the wall of my office is a pair of Straight Tin Snips. They are on the front of our company T-Shirts and will forever be a building block of any micro tin shop.

Straight Tin Snips I use daily

Straight Tin Snips I use daily

Known as Lather Snips to some, I have always labeled them as straight cut tin snips or shears. I have spent over 15 years of my working life cutting straight duct, plenums and fittings by hand with these and other kinds of tin snips. However, these were by far the Labron James of snips in my Tin Knockers tool bag and on the sheet metal fabrication table.

The manufacturer will tell you wide curves can also be cut, and to a point, you can with the Straight Cut. However, I would argue that the longer handle Bulldog Pattern Snips provide an easier cut when dealing with radius shearing. The Bulldogs are for "nibbling" heavier gauge and they do a great job in that forum. But they do a much better job than the straight cut snips when you have to cut a 40" flat elbow cheek and especially when cutting smaller radius lines by hand. Bulldogs saved me a lot of frustration on those days when fittings prioirized the schedule. 

Bulldog Tin Snips We Use Each Day

Bulldog Tin Snips We Use Each Day

The straight cut snips hang up too much as you make your way through the radius. They can't make the corner nice, especially on those tighter curves. Think of a good handling car versus a bad one. Both vehicles can make the turn. However, you can feel the difference if you've driven the car that really handles well in the corner. It can make all the difference when time is of the essence. 

Having both pairs of snips at your disposal can only help your fabrication prowess. 

Every sheet metal worker, roofer or HVAC technician will have a pair of Straight Tin Shears at the ready. They are tried and true; the backbone of a Tin Knockers tool bag. I would bet many of them carry a pair of Bulldogs as well.

Today at K & E Sheet Metal they have taken a back seat to the CNC plasma table and pneumatic jump shear, but they still hold tremendous value in our shop on a daily basis.  They were the tools that built this company to where we could afford the plasma table and jump shear.

If you're working in the field and you don't have a pair in your tool bag, do yourself a favor. And if your're starting a small fabrication shop, they are a must. Those aviator snips you may have picked up at the local Home Depot are immensely important when it comes to sheet metal cutting tools, but they will soak up your time and forearm strength in seconds.

The Straight Cut Tin Snips and Bulldog Pattern Snips will help take care of that problem and keep your cuts straight and true.  

Happy Cutting!

Sometimes Important Business Tasks Can Get Overlooked

Many times a small business will overlook something important. With us, one of those extremely important things has been customer retention. Don't get me wrong, our work speaks for itself and many of our customers have been coming back for years. The retention I'm talking about are those fringe individuals or companies we neglected because we were either, too busy or too lazy to take the time and keep up relations. The customer came in for a minor piece of fabrication and we let them get pushed to the bottom of the pile, assuming they would never come back anyway. However, those are the customers who may give your name to a friend or family member, making them a powerful resource to keep communicating with.

Earlier this week I received a call from a company called Intuit Demandforce. We have used Quickbooks for invoicing, so getting a call from a company in the Intuit family is not out of the ordinary. Most of these calls I will greet and pass on because they are just an introduction to get you in the door, nothing more. Yet, this one seemed a little different. I got the sense they really wanted to show me what the service could offer, I wasn't feeling sold to. Could be a testament to the sales person on the end of the line but, I felt the risk was worth it and agreed to a web share about the Demand Force service.

From the Demandforce website:

Keeping up with all of the changes in technology and online services is hard, but you need to communicate and market like the big boys or your business won't survive. Demandforce is here to help.
 
We take an award winning communication portfolio, with easy to use <a>online reputation tools and our broad consumer network, to become the marketing team your business needs.

The web share went well and after seeing what Demandforce had to offer I decided to give them a shot. Our account went live today and I am very excited to see how the service will help business over the next month. I really like the people I have dealt with so far, giving me a personal experience you don't get with many online businesses. Everyone genuinely seemed to care about us succeeding with the program.

Updates to follow :)

originally posted on our Facebook Page 

SaraSpa Rod & Gun Club Duct Fabrication

After installing the filter boxes and elbows shown in my previous post, it is now time to fabricate the next set of duct and transitions that will run up the wall. There are three total units and each will need a 90" drop. Below are the in-progress fittings lined up in a pretty little row.

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Our next task is to cut and install the Ductmate Flange System on each section of duct for easy installation when we get to the jobsite.

Wolla!

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We finished up a few 90 elbows with turning vanes for the job as well. Probably could have managed a better photo but I had to assist my helper uncle with that tub of screws :)...JK