Gateros Plating

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Hints and Tips Page
 
I will try and post relevant information as frequently as possible, most of it will be about plating and some will be general restoration tips. Please feel free to email me with any good tips and tricks as these can save a lot of time and effort.
 
I will try and put everything in sections alphabetically to make it easier for you to find.
 
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 basically the removal of any oxide layer that may form on the surface of the metal.
The activation process which may in part be 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 at best staining and at worst skip plating or even de lamination and blistering.
 
Soft metals such as zinc, copper, bronze and brass are easily activated with a simple pickle process or acid activation.
Our Dry Acid salts are ideal for this type of activation.
Harder metals such as Stainless steel, Nickel, Replica Chrome and steel can also be activated with an acid pickle but 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.
 
Remember 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!
 
When activating soft metals such as copper, zinc and brass etc it is particularly important to rinse extremely well after acid pickle process.
If rinsing is not thorough, staining will be seen and it tends to be mainly on the edges!
 
Activation using a current can also be done in the Dry Acid pickle solution.
Refer to Dry Acid data sheet for full details on specific rates and current.
 
 
Agitation
 
Agitation is a very 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 the better the agitation the better the finish.
 
Zinc plating in particular, produces better results with agitation but all types of tank plating will benefit from some form of agitation while plating. 
 
There are several methods that can be used;
 
Air is one of the cheapest ways to agitate the electrolyte while plating and all of our kits are designed to be used with this form of agitation. The simple method is to use a fish tank air pump and some plastic tube. I find that a small amount of silicon will hold the plastic tube in position at the bottom of the tank, obviously 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 a bubble wall 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. The pumps and accessories are usually available from pet shops or aquatic suppliers.
 
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 really practical. 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 usually need to be submerged in the water to work. We have customers that use this type of agitation but because the electrolyte is acidic, I don't know how long the pumps will last! 
 
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, this can be done.
 
Brush plating systems are usually cheaper and our brush plating kits contain a power supply and most items that you need to plate.
 
Some disadvantages 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 thiskness of the plate so the surface needs to be prepared better, replacement solutions are needed when brush plating a lot.
 
 
Cleaning
 
After seeing one or two customers of late with contamination problems (most of which we have been able to solve with having to replace the electrolyte) I want to stress again just how important cleaning is to both 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.
 
First step is a good de-grease. This can be done with a solvent type degreaser or a hot alkaline degreaser such as our GP1 alkaline cleaner.
 
The next step is to remove any traces of rust, paint or dirt. This can be done by electro-cleaning, bead blasting or even buffing on a wire may be sufficient. Remember once you have started the cleaning process you must always wear gloves as even the grease off your fingers will cause the plating to blister at a later date!
 
Once you have completed the first part of the cleaning process, I would now advise a water break test. Just dip in clean water and see if the item is covered with a water film or if it beads. If it has a good 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.
 
Now onto the pickle. Some people try to skip this part but it is very important not to as it will ensure a good bond between the surface of the metal and the following plate.
Our dry acid pickle is specially formulated for use as a plating pickle or as a metal activator. You can also use HCL ideally at concentrations of about 20%. Some people use sulphuric acid but I find it a bit smutty on some metals. We have had customers use vinegar but this is just not strong enough for the job! Pickling time varies according to the type of metal and the strength of the pickle used. It is normally between 1 minute to 20 minutes and remember always rinse well after pickling.
 
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 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. You should be able to buy one for as little as £35 for a 3/4 HP 220v one.  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!
 
 
Mechanical Cleaning

Another method of cleaning prior to plating is mechanical cleaning. This can be achieved in several different ways. Sand blasting or media blasting is and option. So is sanding or cleaning with pumice powder. Infact anything that will take a thin layer of metal from the surface of the item being cleaned will work. Remember when doing any type of cleaning to wear clean gloves! After you have mechaniclly cleaned the item you should then wash it in hot detergent and water and theck that it passes a water break test. if it does than plate straight away.
 
 
Electrolyte

Keeping the electrolyte clean is very important as it will prolong the life of the electrolyte and ensure high qulaity 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 uf using the current controller then all of 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 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 electro-clean, use alkaline cleaners heated so immersion times are reduced in the following processes, make sure rinses are good 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 if zinc plating items before passivating), oven bake items at temperatures arround 350C for 2 hours minimum.
 
 
Heating
 
When the ambient temerature drops and the plating tanks are unheated then it is time to consider some form of tank heating. All plating electrolytes will benifit from tank heating of some form. Easy ways to heat the tanks are as follows:
 
For small tanks
1) simply place them in a bowl of boiling water and wait for them to warm up.
2) Fill a plastic bottle with near boiling water and place inside the tank taking care not to overflow the tank.
3) Place the tank on a heat mat normally for lower plating temperatures but will still raise the temperature.
4) Thermostatic tank heaters are the easiest method as you can preset 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
1) Thermostatic tank heaters are the best method for larger tanks.
2) Heated air agitation is sometimes used in very large tanks.
3) Combined heat and filtration systems are also used.
4) 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!
 
Temperature ranges for our plating electrolytes.
 
Metal                  Range                 Ideal
 
Zinc              15°c - 40°c         25°c  - 30°c
 
Copper          15°c - 50°c         25°c  - 40°c
 
Nickel            30°c - 50°c        30°c  - 40°c
 
Rep Chrome    30°c - 50°c        30°c  - 40°c
 
Brass             20°c - 40°c        25°c  - 35°c
 
Cobalt           30°c - 50°c        35°c  - 45°c
 
 
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