How to treat early signs of rust
Catch small surface rust issues early on when they first appear. If you catch them early enough, the rusted area is easily treated and cleaned away. Spot and repair scrapes, dents, and scratches, should be dealt with before they show signs of rust, to prevent further corrosion damage that could worsen the issue from a non-structural problem to a structural problem.
The initial signs of rust should be removed. First prepare the problem area by using a wire brush or sand paper to sand down any visible rusted surfaces.
To properly remove the rust, you need to sand right down to bare metal where you can no longer see any signs of rust. After the surface rust has been completely removed, wipe the bare area with vinegar and allow to dry. Once the vinegar has dried, you may apply a layer of rust inhibiting primer or use marine grade DTM (direct to metal) paint to cover the area. If the surface rust problem is more advanced, the remedy is to completely sand blast the exterior container walls and seal and freshly paint the container. For most storage uses, the expensive process sandblasting and completely refurbishing the container is not required.
How do I prepare my container for painting over rust?
As a rough guideline – to repaint a 20-foot container you will require four gallons of paint, and need eight gallons to cover a 40-foot container.
Prepare your container for primer and/or paint application by first sanding down any visible rust patches. A pressure washer is ideal for washing off any layers of dirt and dust. Sand rust patches down with a wire wheel or sandpaper.
It’s a good idea to apply a rust inhibiting primer coat over the area first to ensure the top coat of paint adheres to the metal.
Get the advice of your local paint vendor to determine which primer they stock will be best for outdoors metal surfaces.
Allow enough time for the primer coat to completely dry before applying the final, top coat of paint.
What kind of paint should I use for rust proofing my shipping container?
There are a number of options that you can find to suit your needs, paint availability and budget.
Choosing the correct paint for your shipping container
The type of paint you decide on for your container will depend on how you intend to use it.
1) A water based paint (that is better for the environment with lower VOC levels). With proper preparation and application, water based paints can be equal or better at inhibiting rust – compared to the traditional oil-based paints.
2) Industrial grade alkyd enamel paints are reasonably inexpensive and easy for non-professionals to work with.
You can expect your alkyd enamel finish to last between five to ten years.
3} Polyurethane paint is a heavy duty paint seen in industrial use. It’s important to be aware that the chemicals in the paint can be more hazardous to use. Since there specific procedures for the mixing and application of polyurethane paint, you may wish to seek the services of a professional to apply this type of paint.
4) Zinc paint. Using an application of zinc-based paint will slow the onset of shipping container rust effectively. By a process know as ‘cathodic protection’ – the zinc in the paint slows the rate of rusting of the underlying steel.
Sandblasting the entire exterior of the container is not recommended for most cases. Sandblasting an entire container is a costly process as you need to engage a professional who has the equipment and the sandblasting will completely remove a lot of great protection provided by the original high quality marine grade paint. Since a home paint job is not going to offer the same level of rust protection as the original paint, the wise course of action is to prime and paint over the original marine paint.
Position the container on a level foundation
The easiest step you can take to protect against the effects of water and rust is to position your shipping container on level ground – as opposed to a low lying depression where rain water will collect.
If puddles of water accumulate under or around the container, the conditions are there for rust to rapidly develop. If your 40 high cube container for sale is set directly on the ground, the bottom is in contact with ground moisture and more likely to rust.
First, select a location that is on raised and level ground. Builders recommend setting your Conex container up on a basic foundation using a simple foundation of concrete blocks or railroad ties – which will also have the added benefit of improving air circulation under the container..
A common problem area to look out for is the bottom of the container doors as water tends to collect in that area.
Maintain container door hinges and gaskets
While shipping containers are simple structures with few moving parts, we do need to perform some maintenance on the doors.
The easiest and most obvious is to lubricate the container door hinges. Metal hinges can seize up after a long period of disuse. Applying an all purpose lubricant like WD40 or 3in1 oil when you do a container check, will keep the hinges from rusting and getting bound up and doors working smoothly.
Replace worn rubber seals on doors.
Shipping containers are engineered to be a watertight sealed environment and the metal doors utilize rubber gasket type of seals.
The rubber generally have a life span of close to 10 years before cracking, degrading and losing their ability to rightly seal the door against moisture. In the case of badly degraded seals, you can replace them with a container door gasket kit available online.
By paying attention to these tips, you can ensure your shipping container storage unit protects your items for many years.