Galvanizing bath. The container used to hold the molten zinc. Sometimes referred to as pot or kettle.

The frame we hook or wire smaller sections/fabrications to for galvanizing.

New steel or iron castings are usually suitable for galvanizing. Older castings can be more problematic. Contact us for details.

The passivate solution used by Shropshire Galvanizers as part of the post-treatment for galvanized steel. The hot steel is dipped into the chromate solution to cool and protect the zinc’s shine. The solution also helps reduce the build up of white storage stain on the galvanized coating.

Coating thickness
Hot dip galvanizing coating thicknesses usually depend upon the steel thickness, for example a steel section of 6mm thick or greater should pick up a mean minimum coating thickness of 85 microns. A one coat powder coating thickness is likely to be around 60 to 80 microns.

The zinc is maintained at around 460oC. In some instances, when submerged into the zinc, stresses in steel (usually formed during the rolling or fabrication stages) can make the steel distort.

Double dip
Dipping one end of an item (that is too long or deep to fit into the bath in one dip) withdrawing it and then dipping the other end. This will result in a double dip line where the two dips slightly overlap but enables galvanizers to dip items deeper or longer than their bath dimensions.

Drainage holes
Hollow sections with closed ends require venting and drainage holes. Galvanizing requires sections/fabrications to be completely submerged into the molten zinc. To enable this, a ventilation hole must be located at the top of every closed section and a drainage hole be located at the bottom.

Duplex coating
Two coating types such as galvanizing over-coated with powder coating.

After polyester, epoxy is the second most popular powder coating resin we offer. Epoxy offers especially good chemical resistance but is not usually suitable for outdoor use as it is not as UV stable as polyester.

When we galvanize and powder coat, we ensure that the galvanized coating is fettled smooth before powder coating takes place. Also referred to as dressing or linishing. We only fettle our own galvanizing prior to powder coating.

The flux solution is part of the pre-treatment for the galvanizing process. It is a 30% zinc ammonium chloride solution and maintained at around 70oC. The steel is dipped in the flux prior to galvanizing to help remove any final traces of oxide from the steel and to aid the galvanizing process.

Galvanized steel emits gasses when subsequently heated up in a powder coating oven. If not treated these gasses can escape through the powder coating creating little bubbles in the powder coating surface. Our powder coating powder contains a ‘de-gassing’ ingredient to help greatly reduce such instances.

Gloss level
Most powder coating colours are available with a choice of gloss levels or sheen. The main ones are matt (approx. 30% gloss) sometimes called satin, semi-gloss (approx 60% gloss) and gloss (approx 80% gloss). The most popular is 30% gloss.

Grit blasting
See shot blasting.

Hydrochloric acid
Part of the pre-treatment for the galvanizing process. The steelwork is submerged into a tank of dilute hydrochloric acid to remove rust and mill scale. Steel must be clean for the galvanizing process to take place.

Another term used for bath.

Moveable parts
Adequate clearance must be left between surfaces for hinges etc if they are to move freely after galvanizing. An extra clearance of 1mm is usually sufficient.

See chromate.

Another term for the hydrochloric acid pre-treatment stage.

Most powder coatings we offer are pigmented polyester resin. It offers some corrosion resistance and is UV stable (good for outdoor use). Compare epoxy.

Another term used for bath.

In powder coating, where the steel is located outside but galvanizing is not appropriate, we recommend that we first apply a powder coated zinc-rich primer before powder coating the ‘coloured’ top coat. The primer will help protect the steelwork from rusting.

Repairing (damage, welds, cutting) a galvanized coating can be done under BS EN ISO 1461 (2009) usually using a wire brush and then sufficient coats of zinc rich paint (by brush or aerosol).

Repairing scratches in a powder coat can be done using a colour matched tin or aerosol paint.

Iron and steel are prone to oxidisation. Protect your steel with hot dip galvanizing and/or powder coating.

Shot blasting
We shot blast using chilled iron grade G17. The steel is blasted with iron particles to either clean its surface of impurities such as old paint systems, oil, grease etc or to ‘rough’ up the surface to prepare it for powder coating and in some cases galvanizing.

Silicon steel
Silicon can be added to steel as a deoxidant during the production process. Too much or too little silicon in steel will affect the coating and usually results in a much darker and thicker coating that in extreme circumstances can be prone to handling damage.

Stainless steel
Stainless steel does not galvanize well. After the galvanizing process it may be bare of zinc or blackened. Contact us for details.

The British standard we hot dip galvanize to is BS EN ISO 1461 (2009). The British standard for powder coating galvanized steel is BS EN 13438 (2005).

A chemical etch applied to a galvanized coating to key it ready for the powder coating process.

Thicker coatings
To increase the natural galvanized coating thickness, the steel can first be grit blasted to ‘rough up’ the surface. The zinc thickness may be increased by up to 65% this way. This is only really relevant for extreme applications where steel is exposed to excessive salt spray, excessive humidity or aggressive corrosives.

Ventilation holes
Hollow sections with closed ends require venting and drainage holes. Galvanizing requires sections/fabrications to be completely submerged into the molten zinc. To enable this, a ventilation hole must be located at the top of every closed section and a drainage hole be located at the bottom.

Warm to touch
A plastic powder coating that is usually much thicker than the standard polyester coatings. The plastic powder offers good thermal insulation making it ideal for handrails. It also has good chemical resistance.

Welding slag is not removed by our pre-treatment process. It does not galvanize well and can lead to bare black areas if not removed by you prior to galvanizing.

Raised weld seams can occur during galvanizing (a thicker zinc coating on the welds than on the steel around it). To avoid this it is recommended that the silicon content of the welding rod material be less than 0.04%.

Anti-spatter sprays and weld test solutions should be water soluble or completely removed by you prior to galvanizing.

Note: Care must be taken when welding to ensure that welds are not porous. Pre-treatment chemicals may enter the micro pores of the weld and subsequently leech out post galvanizing leaving unsightly brown stains.

Wet storage stain
White corrosion products and darker areas on a galvanized surface. This usually occurs when the galvanized steel is tightly packed together in damp conditions. Storage in dry, well ventilated areas is the solution. Can be removed with wire brush.

Zn. The molten metal the steel is galvanized in. Melting point 419.5oC