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ThicknessesThe choice of the most suitable anodizing thickness, and consequently the thickness of GHA® treatment, should be based on customer's needs and desired performances. The thickness range is from 5 to 200 µm, depending on the specific alloy used.Here are the maximum achievable oxide thicknesses for some of the main alloys suitable for anodization:5000 AND 7000 SERIES : maximum thickness 150-200 µm;6060 ALLOY: maximum thickness 100-150 µm;6082 ALLOY: maximum thickness 80-100 µm;CASTING ALLOYS: To be evaluated on a case-by-case basis based on composition and homogeneity.The most suitable choice for each customer must always be made based on a cost/performance ratio, that should be appropriately evaluated together with GHA Europe® company, which will help to achieve the best solution.

AlloysAs it is well known, aluminum is a metal with excellent characteristics, but it is limited by poor mechanical properties. For this reason, aluminum-based alloys were developed to enhance the characteristics of the base material with the addition of various elements that confer their properties in a specific combination to suit different needs.The choice of an aluminium alloy suitable for anodization must be made based on several factors:Cost;Ease of processing;Mechanical properties;Anodic oxide quality;Availability.It is important that the choice of the alloy is based on the field of application and the requirements to be achieved.1000 SERIES AT 99% Al: Food grade – Poor mechanical properties – Good oxidizability;2000 SERIES Al-Cu: Non-food – Not suitable for anodic oxidation;3000 SERIES Al-Mn: Food grade – Rarely used in mechanics – Rarely treated with anodizing processes;4000 SERIES Al-Si: Food grade depending on composition – Suitable for anodic oxidation if the silicon content is less than 9%. However, this has to be evaluated on a case-by-case basis;5000 SERIES Al-Mg: Food grade – Moderately good mechanical properties – Good oxidation but poor aesthetic finish. Porous oxide;6000 SERIES Al-SiMg: Food grade – Moderately good mechanical properties – Good corrosion resistance – Good oxidation with excellent aesthetic and technical finish;7000 SERIES Al-CuZn : Non-food – Excellent mechanical properties – Poor corrosion resistance – Good oxidation with good aesthetic finish and optimal final mechanical properties; corrosion resistance lower than other alloys with risk of blistering (see defects section );GHA Europe® is available to provide any advice towards the choice of the most suitable alloy and treatment according to the customer's needs.

TolerancesDimensions and tolerances must be calculated before manufacturing the parts, based on the required treatment thickness.Aluminium oxide (and consequently GHA® treatment) grows directly onto the aluminum substrate, penetrating approximately for half the total thickness. This means that, on a flat surface, a 50 μm total treatment thickness will generate a net traslation of the surface of about 25 μm towards the exterior.When we talk about tolerated holes, however, the final diameter decrease will be the same as the thickness of applied treatment. This means that a tolerated hole on a part that requires 50 µm of treatment has to be initially 50 µm wider than the desired final diameter.In many cases it is also possible to mask tolerated areas and holes with caps, chemically resistant adhesive tape or special paints. In this case it is best to calculate those dimensions using the final values, because they will not be affected by the treatment.

Localized treatmentIf some treated parts require specific modifications and localized reworking, it is possible to re-perform the treatment only in those areas, without altering the existing oxide layer.It is essential that the machining reaches the bare aluminum substrate, that the reworked surface is uniform and clean (see example images below) and that the edges are adequately rounded to ensure an optimal final result.Parts made of 7000 and 2000 alloys present greater risk of deterioration when retreated, as they are less resistant to the acidic products used in the anodization process, especially if they were not properly sealed during the first treatment. For this reason, we cannot guarantee that parts not originally treated by GHA Europe® will yield optimal results after the retreatment.

DeoxidationsAnodic oxidation is a treatment that can be attacked by highly acidic and basic solutions.Thanks to controlled baths of nitric acid and sodium hydroxide, we can chemically remove the treatment (deoxidation) so that it can be re-performed according to the customer's specific requests.When choosing to deoxidize parts, it is necessary to take into account their dimensions and tolerances as the treatment penetrates the aluminum substrate for half its thickness, so removing it means directly eroding the surface of the base metal.In this case we can proceed in two alternative ways:It is possible to mask holes or other areas with special caps, tapes or paints to prevent their surface from being affected by deoxidation (and subsequent re-treatment);It is possible to treat the parts after deoxidizing so that the new oxide thickness value restores their dimensions to about their original state. Following this method generally means reaching an oxide thickness that is more than double of the original value.E.g. To restore a deoxidized part that had a thickness of 20 µm of oxide or GHA®, it will be necessary to re-oxidize the part with a treatment thickness of at least 40 µm.In any case, all assessments must be made on a case-by-case basis, measuring (if necessary) the parts before and after the treatment with specific equipment to guarantee the success of the process.Another aspect of deoxidation is the substantial deterioration of the surface finishing because of increased roughness and porosity, especially when removing very thick oxide layers or retreating certain alloys. In most of these cases we can restore ouselves the surface finishing by brushing and polishing it or we can recommend to the customer the most suitable pre-treatment finishes for a proper restoration.Sometimes it can be more convenient, considering the final result, to rework some specific areas.

ColorsThe addition of silver, intrinsic to GHA® technology, affects the interference of light that passes through the oxide layer, resulting in a characteristic set of colors that depends on the aluminum alloys used (series and metallographic structure) and the oxide thickness. It is therefore good practice to submit reference samples prior to production (sampling is usually provided free of charge).We would like to point out that GHA® is a performance treatment (it has antibacterial, anti-wear, anti-corrosion and other properties) and not a color treatment. What is of the utmost importantance for us is to guarantee the achievement of our customer's specific technical specifications.Obviously, where requested, we can provide the customer with a color as close as possible to the desired one, compatible with the colorimetric range possible with GHA®.In this regard, it is important to keep in mind that color is primarily influenced by the alloy and, secondarily (but no less importantly), by its metallography. Surface finish (satin, polishing, tumbling, sandblasting, etc.) is also a variable that must be verified through preliminary sampling. It is therefore possible for two parts made from alloy 6082 to have different colors even with the same treatment thickness and despite being made in the same wet process. Unfortunately, even parts made from the same bar can be different colors, as illustrated in the FAQ " Can parts made from the SAME BAR be a DIFFERENT COLOR ? "

Defects The corresponding AITAL (Italian Association of Aluminum Surface Treatments) monographic factsheet can be consulted at www.aital.net/download/schede-difetti . Below, however, we illustrate the main defects that can be found. SURFACE BLISTERING: Typical defect of 7000 series alloys (rarely found in other alloys) which consists of a swelling of the surface oxide layers. This defect is caused by the inclusion of oxides, or other heterogeneous particles, in the outer layers of the extruded part, associated with gases. When the part undergoes thermal changes during the oxide formation and bonding phases, these inclusions tend to migrate to the outer layers, consequently swelling the anodized protective layer. These blisters turn into areas of weakened oxide and, if scraped with sandpaper, they break, exposing the underlying metal. There are various possible solutions to be evaluated on a case-by-case basis to minimize or avoid the problem, but it is certain that these "bubbles" create actual craters of variable size in the base material, and it is not sufficient to remove the oxide layer and re-treat the pieces, even if adequately prepared, before repeating the anodic oxidation. In these cases, it is advisable to change the material and isolate the bars that have presented this critical issue. FLAMES, STREAKS OR BANDAGES: A defect that is undetectable before anodic oxidation, but sometimes detectable after pickling. After anodizing, the appearance is characterized by lighter or darker areas than normal. The origin is to be found in the distribution of undissolved intermetallic phases or, sometimes, of heterogeneous particles in the base material. Streaked details are rarely recoverable through anodic oxidation, some finishes can make it less evident but such streaks are intrinsic to the base material and usually result from the extrusion or casting process of the metal. WELDING: Welding an aluminum part requiring anodic oxidation is, if done accurately, primarily an aesthetic issue. It's important to use the same alloy as the base material; in any case, the thermal stress to which the affected area is subjected risks causing the weld to take on a different color than the base material. It is recommended, where possible and necessary, to perform TIG welding without filler metal. CORROSION PITTING PRE-TREATMENT: Aluminum (especially the 7000 series alloys) is a material subject to spontaneous oxidation. If left wet with water or machining oils after machining, it tends to corrode. Sometimes the corrosion is evident and can be addressed with appropriate finishing techniques before treatment, other times the corrosion defects (which can also be deep) are highlighted by the oxidation itself, resulting in a defective surface layer. The only solution is to deoxidize the parts, finish their surface to restore homogeneity in the material (if the tolerances allow it) and then re-treat.

All parts treated with anodic oxidation, and consequently with GHA® technology, are sensitive to excessively acidic or basic pH, it is therefore recommended to clean the affected areas with preferably neutral or medium-aggressive washes, whose pH falls within a range of 4 to 8.5. The following are not recommended: Washes with excessively basic components (Ph>8.5), especially if carried out at temperatures above room temperature; Washes with excessively acidic components (pH<4), especially if carried out at temperatures above room temperature. GHA® is an antibacterial treatment (bactericidal action), therefore it does not require particularly aggressive cleaning on its surface, suitable for sanitizing parts intended for contact with food or pharmaceutical products. The good non-stick properties of the GHA® treatment facilitate the removal of dirt and encrustations, allowing for effective cleaning even with mild washes or with the use of abrasive cloths (such as sponges and kitchen scouring pads). Recommended: Washing with demineralized water can also be carried out with high-pressure, high-temperature pressure washers; Steam cleaning; Washing with medium-aggressive detergent products with a pH between 4 and 8.5; Washing with solvents (acetone, alcohols). GHA Europe® is available to provide advice on the type of washes and detergents to use based on the customer's needs, conducting targeted laboratory tests if necessary, and also offering to develop dedicated solutions in collaboration with manufacturing companies.

Transport document (DDT) The transport document accompanying the material shipped to GHA Europe must contain the following information: The wording "Processing account" or equivalent if the material is to be treated normally; the wording "Repair account" or equivalent if the material is to be treated under warranty or the wording "Viewing account" or equivalent if the material is free samples (previously agreed upon) or similar; The drawing number (or code) of each type of part sent, with the quantity, the type of treatment required and its thickness next to it; Any additional work to be carried out on the parts, such as protection from treatment, brushing, polishing, ...; Any requested delivery dates, which must be clearly visible on the delivery note; The possible presence of drawings to be returned with the details treated; The address to which the treated material will be shipped and the shipping method (recipient collection; collection by a carrier called by the recipient, collection by a carrier paid by GHA, etc.).

Packaging If the parts are transported by a carrier, to preserve their integrity, it is recommended to use rigid packaging made of metal, wood, or plastic, inside which the parts are prevented from moving and colliding with each other. It is recommended to apply at least one layer of bubble wrap to separate each part. As the part's mass increases, the amount of padding surrounding it should also be increased. If it is not possible to use rigid packaging, we recommend at least insuring the shipment against possible damage caused by transport.

Delivery times and urgencies For medium-sized supplies (less than approximately two standard pallets), we can guarantee processing within 5 working days of receiving the material, excluding complications not caused by GHA Europe®. The exception is semi-hard anodic oxidation, which is usually only performed on Monday mornings; therefore, material requiring this treatment cannot be ready before that day. If the customer needs the item to be returned sooner, it is possible to request urgent processing by adding a supplement to the total price: Delivery within 48 hours: +15%; Delivery within 24 hours: +25%; Same-day delivery (morning to evening or afternoon to next morning): +40%. The minimum emergency surcharge is €50.00 + VAT. This may vary if the items in question present particular critical issues. Urgent requests must be made by clearly indicating the requested delivery date (and time) on the delivery note and, if possible, by calling or sending an email to notify the customer of the incoming material. It is not always possible to carry out the treatment with the required urgency, in which case GHA Europe® will contact the customer immediately to arrange another delivery date. It's also important to consider shipping times, which for large carriers like GLS, BRT, DHL, UPS, etc., generally exceed 24 hours from pickup. Pickups with these carriers must be booked by 12:00 noon on the day of delivery, and the items must be ready for pickup by 2:30 pm the same day. GHA Europe® can arrange both national and international collections and deliveries through its partner carriers, GLS, BRT, DHL, and UPS.

Treatment price calculation To find out the cost of treating a particular part, the simplest way is to send its drawing in STEP format (or PDF if not available) to ghaeurope@gmail.com . The following information is required: Type of treatment required (GHA, Hard Oxide, …); Required thickness (20 μm, 45-55 μm, …) Aluminum alloy used (6082, Fibral, …); Whether or not additional work is required (cleaning, finishing, protection, etc.); Expected quantities (lot sizes); Any deadlines . If you have difficulty finding any of the above information, GHA Europe® will be happy to assist you in choosing the optimal parameters. For example, if you don't yet know the treatment thickness to apply, please let us know the previous treatment, the function of the part, and the type of wear or corrosion you wish to prevent. GHA Europe® will help you determine the most appropriate thickness. GHA Europe® is always available to take samples should testing be necessary. The price of the treatment is calculated as follows: The surface area of ​​the part is estimated, generally via drawing (the STEP format is ideal as it allows for instant calculation of the same); The surface area value must be multiplied by the price per square meter, which depends primarily on the type and thickness of the treatment. Furthermore, the price per square meter decreases slightly as the size of the part increases; Supplements may apply in the case of particular: with small surface area but large footprint; which involve significant assembly difficulties; built with alloys not suitable for oxidation; that need to be cleaned, finished or protected before treatment; If urgent delivery is required , the total price must be multiplied by a factor depending on the degree of urgency.