This section will contain useful bits of information about electroplating and general restoration. They are in alphabetical order.If you have any good tips and tricks please get in touch and we will add them down below.
Activation:
Activating the metal surface prior to plating is one of the most important parts of the plating process and is often overlooked!
Activation is the removal of the oxide layer that forms on the surface of the metal by a standard acid metal chemical reaction where hydrogen ions take electrons from the metal oxides to form hydrogen and metal salts.
The activation process‚ which is based on acid activation or an acid pickle‚ will also remove any alkaline soaps that remain on the surface after an alkaline cleaning process. Both alkaline soaps and oxides will cause staining and can cause skip-plating, delamination and blistering.
Soft metals such as zinc‚ copper‚ bronze and brass are easily activated with a simple pickle process or acid activation, such as ourdry acid pickle salts. When activating soft metals‚ it is particularly important to rinse extremely well after the acid pickle process to remove all traces of acid. If rinsing is not thorough‚ staining will be seen, usually on the edges of an item.
Harder metals such as stainless steel‚ nickel‚ replica chrome and steel can also be activated with anacid picklebut the immersion times will be longer and the concentration of the pickle will be higher.
Another way to activate some of the harder metals is to use a current reversal process after an acid pickle. This is done by reversing the polarity in the plating tank for 30 seconds just prior to plating. Metals that benefit by this type of activation are Nickel‚ Replica Chrome and Stainless steel. If using the current reversal process‚ items should be pickled and well rinsed prior to going in the plating tank. Do not use this type of activation for longer than 30 seconds!
Agitation:
Agitation is another important part of the plating process that is often overlooked by home platers. It is true to say that for small parts you can often still get good results without it, but in general having agitation will increase the quality of the final results. Agitation helps with the removal of materials from the metal surface, increasing the electrode potential making plating more efficient and also to help prevent the build-up of impurities in the surface layer.
Zinc plating produces better results with agitation but all types of tank plating will benefit from some form of agitation while plating. When using agitation while copper plating, make sure your anodes are wrapped or in anode bags. The dissolution of the copper anodes causes larger particles to be deposited into the electrolyte, without anode bags and with agitation, these particles will be deposited onto your items causing a dull and grainy finish.
There are two main methods that can be used, air and mechanical.
Air is one of the cheapest ways to agitate the electrolyte while plating. The easiest way to use air to agitate is to use a smallair pumpand some plastic tube. A small amount of silicon will hold the plastic tube in position at the bottom of the tank. You will need to empty and clean the tank before you can silicon the tube in position.For larger tanks or if more air agitation is needed then you will need a larger output pump. Again, fish tank pumps can be bought in different sizes with varying levels of air output and you can add an air stone to this so you are getting lots of agitation. If you want to make your own bubble wall out of the air tube then block off the end of the air tube and drill some 2mm holes in it near the blocked off end about 1cm apart. Test it in a bowl of water to see if you need more holes.
Mechanical agitation can also be used and can be as easy as stirring the electrolyte while plating. This is fine when doing a decorative plate for 15 minutes but when a thick plate is needed then standing and stirring for an hour is not practical! Instead, a fish tank filter pump can be used. This is not the air type; this type uses a small electric motor with an impeller to produce the flow of water. These pumps need to be immersed in the electrolyte to work.
Brush Plating:
This is a great technique that can be used for plating small items and can also be used to repair items that can't easily be dismantled. It is ideal to give thin decorative coatings but can be used to give thicker coatings if used for longer. It can also be used to plate only certain areas so if you are trying to build up worn areas on a certain item such as bearing journals or housings.
Some points to be aware of are:
slower than tank plating
not as easy to apply thick plates
levelling of the plate is not as good due to the lack of levellers and the reduced thickness of the plate so the surface needs to be prepared better
replacement solutions are needed when brush plating a lot.
Cleaning:
Cleaning is the most important step in electroplating. It is critical in achieving good quality plating and to ensure that the electrolyte is kept in prime condition.
It is vital that cleaning is carried out carefully and that the items to be plated are ultra clean. Remember to always wear gloves and make sure they are clean so that you do not transfer and types of soils, mainly grease from hands, onto your part.
There are a few main steps when cleaning parts for plating. Please be aware that multiple steps are needed on badly worn or pitted items with a lot of oil and grease on the surface.
Mechanical Cleaning
Alkaline Cleaner
Rinse
Acid Cleaner
Rinse
Cleanliness test
Activation
See AlsoBrasso Brass Care KitRinse
Electroplate
Mechanical cleaning involves sand blasting, polishing, buffing, etc. and can be quick and easy. The aim is to remove any traces of rust, paint or dirt.
Alkaline cleaning is used to remove numerous different soils, mainly heavy oils and grease. It can be used as either a soak cleaner, where the part is immersed in the cleaner, or as an electro cleaner.
Acid cleaning will remove any remaining oxides as well as some light soils.
Once you have completed the first part of the cleaning process, it is important to check the surface cleanliness before activating. A water break test is an easy, quick way to check. Just dip in clean water and see if the item is covered with a water film or if it beads. If it has a water film all over it, with no beading, then it can go to the pickle stage. If you can see the water beading then you need to wash in detergent and water, rinse well and repeat the water break test again until it passes. You can also use the white cloth test. Simply rub the part with a white cloth to check for any residues on the surface. If the cloth does not remain white you will need to repeat the cleaning processes before activation.
Activation is critical in ensuring the new surface adheres to the base metal and creates a good bond. The activation acid slightly etches the surface, stripping oxides and metal from the surface to expose pure metal atoms. Our dry acid pickle is specially formulated for use as a plating pickle or as a metal activator. You can also use hydrochloric acid at concentrations from 5% to 20%. Sulphuric acid can also be used on some metals at concentrations from 1% to 10% .
Once pickled and rinsed, you need to plate straight away. This way you will not give the metal any time to form an oxide layer on the surface.
The better you can prepare a surface, the better the results will be. So, spend extra time flatting, buffing and polishing if needed. This is essential when brush plating as you are only putting a very thin plate on the base metal so the more polished you can get the base metal the better. If buffing or polishing remember to remove the polish film with a solvent cleaner if needed and wash in detergent and water again after. Always check with the water break test before pickling.
Think about investing on a bench buffer/grinder. The amount of time and effort it will save you will make it well worth the cost.
Remember cleanliness is next to godliness, so if you want to be a plating god then clean, clean and clean again!
For more information, head over to ourcleaning page.
Electrolyte:
Keeping the electrolyte clean is very important as it will prolong the life of the electrolyte and ensure high quality plating. If you encounter any problems when plating the first thing to do is to do a test plate. This is done by preparing a 2" piece of copper water pipe. Clean with fine wire wool until shiny then washing in detergent and water until it passes a water break test. Make sure the tank is ready for plating so up to temp and agitation on. Plate at low current, so if using the current controller then all the resistance wire in the circuit. If using a variable power supply plate at 0.3 amps. Plate for 20 minutes. If plating is dull then, as per our guide, add a little maintenance brightener and test again. If still dull then filter the electrolyte through coffee filter paper and dummy the electrolyte (do a plate out) add a little more maintenance brightener and test again.
Embrittlement:
Hydrogen embrittlement can be caused by electrocleaning, plating and pickling. It can cause problems with high tensile parts, making them brittle and prone to failure when under stress.
There are several ways to reduce this problem; mechanically clean the item rather than electroclean, use alkaline cleaners heated so immersion times are reduced, make sure rinses are thorough and if tank rinsing make sure water is clean, reduce pickle time to 60 seconds and where possible reduce plating currents and plating times.
After plating (and before passivating), oven bake items at temperatures around 190-220C for 1-2 hours.
Electrolyte Temperature:
When the ambient temperature drops and the plating tanks are unheated then it is time to consider some form of tank heating. All plating electrolytes will benefit from tank heating of some form. Easy ways to heat the tanks are as follows:
For small tanks
Place the tank in a bowl of boiling water and wait for them to warm up.
Fill a plastic bottle with near boiling water and place inside the tank taking care not to overflow the tank.
Place the tank on a heat mat normally for lower plating temperatures but will still raise the temperature. Make sure you only do it this way with a glass or metal tank – plastic will deform and may melt.
Thermostatic tank heatersare the easiest method as you can pre-set a temperature and leave it to warm up. Remember to give it several hours from cold to get to the correct temperature.
For larger tanks
Thermostatic tank heaters are the best method for larger tanks.
Heated air agitation is sometimes used in very large tanks.
Combined heat and filtration systems are also used.
Heated tank jackets.
Once up to temperature the process of plating will keep the tank warm or if continuous plating is done then it may be a case of cooling the tank if it gets too hot!
