Powder coating

Hacklab owns a triboelectric powder coating gun which can be used by members. You can find the gun and its accessories on the second-bottom shelf of the chemical cabinet in the painting room.

Powder coating gun: https://www.electrostaticmagic.co.uk/products/easy-coat-powder-coating-system-starter-pack

For help and guidance contact: Ceravyn (Matrix/Telegram)

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The health risks associated with powder coating are mainly related to the composition of the powder. While the powder itself is not toxic, fine plastic dust can easily be inhaled into the lungs, so wearing a respirator is an absolute must when powder coating. In addition, plastic dust can cause local irritation/contact dermatitis upon skin contact, so it is recommended to use protective gloves when handling the powder.

A good respirator suitable for powder coating has a P3-level rating against fine particles and should fit and seal well on your face. Recommended respiratory masks include:

https://www.motonet.fi/fi/tuote/7003866/3M-6502QL-puolinaamarisarja-ruiskumaalaukseen (Replaceable filter cartridges)

https://www.motonet.fi/fi/tuote/781829/3M-4255-puolinaamari (Fixed filter cartridges)

If you plan to just try out powder coating or use it rarely, a “construction worker's” ffp3 mask can be a decent budget option:

https://www.puuilo.fi/kuppimuotoinen-kertakayttoinen-hengityssuojain-venttiililla-ffp3-nr-10kpl

Especially when choosing inexpensive FFP3 respirators, pay attention to fit. A soft rubber seal around the entire edge of the respiratory mask is usually a good sign. The foldable, non-sealed, and valveless FFP-classified thin ffp-rated masks which grew in popularity during the covid-pandemic rarely seal well and can't be recommended.

It goes without saying that surgical face masks, etc., are definitely not suitable for protection against this type of dust.

Note also that FFP3 respirators do not filter gas/vapor (A-class protection), so they are not suitable for wet (spray) painting if you plan to do both.

The surface of the object to be painted should be cleaned of rust, old paint, and grease, as these prevent the powder coat from adhering properly and can cause bubbling when heated.

Often the easiest and most reliable way to prepare the workpiece is sandblasting, after which the surface can be wiped clean with (for examle) brake cleaner or other solvent.

After cleaning the workpiece, you can use heat resistant tape (Kapton or similar) to cover the areas you do not want to paint. Tape must be able to withstand at least 200°C temperature.

The prepared object is then hung on the oven rack using electrically conductive metal wire. When securing the object, make sure that the rack with the hanging pieces fits well into the oven without the pieces touching the inner walls of the oven. At this point, it's also a good time to turn the oven on.

(Optional): After cleaning, it is also recommended to preheat larger and/or cast iron objects to 200°C for 15-20 minutes to remove any absorbed moisture from the porous surface. Without preheating, the escaping moisture may cause surface bubbling in later heating stages. This is mostly a cosmetic issue, and preheating can be skipped if the surface quality is not a major concern. After preheating, the object should be allowed to cool back to near room temperature before applying powder coating.

Start the compressor from its power switch located near the plasmacutter booth's door, if it is not already running.

Make sure that the pressure regulator in the spray painting room's air line is set to max. 3 bar working pressure to avoid damaging the paint gun! 2-2.5 bar is well suitable for powder coating. If needed, adjust the working pressure by raising and turning the black adjustment knob on top of the regulator, then lock the selected pressure by pressing the knob back down.

Attach the grounding wire, located on the painting room wall, to the oven rack, the metal wire used for hanging the pieces, or directly to the object to be painted. A good grounding point should be of bare metal and close to the workpiece.

Pour the desired amount of powder into the gun's powder container and attach the container to the gun. Try to use a container which has been used for similar colors (marked on the container) or clean the container thoroughly with an air gun before use to avoid mixing colors if the color shade is important to you.

Screw the moisture separating filter onto the gun's handle and attach the compressed air hose to the filter. The gun is now ready for use.

Handle the gun with care. Its “barrel” is brittle plastic. Do not drop or do other stupid things to it.

Spray the powder onto the object from a distance of about 20-30 cm, starting with the difficult-to-reach areas and saving the easier flat surfaces for last. The powder should adhere effortlessly to the object's surface.

The thickness of the layer to be applied depends on the purpose: a single thick layer is suitable for solid-color objects where durability is important.

Multiple thinner layers allow for combining different color shades, using a glossy “clear coat” or including different patterns or logos on the surface by masking. Unlike wet/spray painting, powder coating does not automatically require separate base and topcoats, but these can also be used for specialized purposes.

The powder adheres to the object quite strongly due to static charge, and it does not easily fall off even if the object is moved or the grounding wire is disconnected. However, a surface that is not cured cannot be touched and air gun will be able to remove the powder with ease.

If at this point you realize you have made a mistake in the painting process, you can easily remove the powder you have applied using an air gun and start all over.

Once you achieve the desired layer thickness, disconnect the grounding wire and carefully place the rack into the oven in the firehazard room for curing. Do not, under any circumstances, use the oven in the kitchen for powder coating. The required temperature and time for curing depend on the powder, but 20 minutes at 200°C usually works for most powders and can be used as a general guideline.

Once the object has cooled back to near room temperature, it is ready for use. There is no need for post-processing, and the powder coated layer does not require any additional “drying time.”

If you intend to apply multiple layers, you can apply the next layer as soon as the object has cooled.

Remember to clean up after yourself!

Clean the gun by first removing the powder container and emptying it by pouring any remaining powder back into its bag. Then cover the container's mounting cup with your palm and pull the trigger until no more powder comes out of the gun.

Next, detach the air hose from the powder coating gun and use a separate air gun to clean the mounting cup of the powder container and the “barrel” of the gun. Note that even with a separate air gun, you should not exceed 3 bar of pressure through the powder coating gun.

Lastly, clean the outside of the gun with paper, unscrew the moisture separator filter, and place the gun back in its storage box.

Always vacuum the floor and work “table” in the painting room after powder coating..

Powder can easily spread with air currents, and your fellow hackers are unlikely to appreciate plastic dust in their own woodworking projects when they come into the room to spray paint or leave their projects to dry. It's not cool to ruin someone else's work with your mess.

You can find a vacuum cleaner near the textile workroom's entrance, and the most convenient power outlets for it are either in the kitchen or on the plasma booth's wall behind the plotter.

It's recommended to occasionally clean the oven racks using a wire brush to ensure a good grounding connection for the workpieces. Additionally, the powder buildup on the rack can cause extra fumes in the oven.

Cleaning the inside of the oven from melted powder and other debris is also necessary from time to time.

There is a one SmartStore box for the storage of powders, located next to the powder coating gun in the chemical cabinet. If more powders start to accumulate, they could be separated into two boxes. For example, one for members' personal use and one for “free for all”.

Always store the powders using double bags and seal the bags securely.

Powders stored in a singular bag only will be considered a catastrophe waiting to happen and removed upon notice.

Put your name/nick onto your powder bags. Unlabeled powders are assumed to be “free for all”.

To be suitable for powder coating, an object must meet the following conditions: A) fit into the oven, B) withstand 200°C temperature, and C) have sufficient electrical conductivity for the powder to adhere to the object's surface.

You can therefore use powder coating on metals, glass, or say, ceramics coated with copper spray, for example.

Check the grounding wire. The grounding clip should contact bare metal at a point which is connected to the object to be painted.

The powder used must also be suitable for a triboelectric style powder coating gun. Not all powders can hold static charge and, therefore, will not adhere to the object when using this gun. Confirm with the seller whether your powder is compatible with the tribo-style gun.

A few examples:

Pulverkönig (Germany)

Pulverlackshop (Germany)

Nordic Pulver (Lithuania)

IKH (Finland)

Electrostatic Magic (UK, all powders compatible with tribo, VAT-free for orders over £60 despite Brexit)

Always check the compatibility of the powder with tribo-style gun!