Fault
|
Possible cause
|
Diagnostic clue
|
Corrective action
|
No plating at all
|
Open circuit |
MultiPlater: red light remains on, indicating that no current is flowing. Third-party power supply: zero amps. |
Check all electrical connections and contact points. Clean the contact points if necessary. |
| Reverse polarity |
Current may still flow, but gold does not deposit. The workpiece may show signs of anodic attack. |
Correct the polarity: workpiece negative (–), anode positive (+). |
Plating is dull or matt
|
Plating onto a porous or poorly finished surface |
The gold deposit is sound but reproduces the dull, porous or uneven finish of the surface underneath. |
Polish the article to the required finish before plating. |
| Brightener depleted |
The deposit has gradually become duller as the solution has been used. Plating may also be faster than expected because depletion of the brightener can increase cathode efficiency. |
Add Yellow Gold Tank Plating Brightener. The usual addition is 0.1 mL per litre of plating solution. Do not add more than 0.2 mL per litre at any one time. |
| Organic contamination |
The deposit becomes dull or matt despite the other operating conditions being correct. |
Treat the plating solution with Carbon Powder to remove organic contamination. |
Burnt deposit, especially on corners and edges
|
Amps too high |
Yellow Gold Tank Plating Solution is relatively resistant to edge burning, but excessive amps can eventually produce a dark or burnt deposit, usually appearing first on corners, edges and other high-current areas. |
Check the surface area and use the Yellow Gold Tank Plating Calculator to determine the correct amp setting. Reduce the amps if necessary. |
| Article too close to the anode |
Localised burning occurs on the part of the article closest to or directly facing the anode. |
Move the article in the beaker or rearrange the anodes to increase the distance between the article and the anode. |
| Gold content too high |
Burning occurs despite otherwise suitable operating conditions, particularly after excessive additions of Yellow Gold Tank Replenisher. |
Reduce the amps in 10% increments until burning disappears. Do not add further Yellow Gold Tank Replenisher. As the excess gold is gradually plated out, increase the amps towards the normal setting. |
| Too little agitation |
Burning or darkening occurs in higher-current areas and agitation is below the recommended medium–high level. |
Increase agitation to within the recommended range. |
| Temperature too low |
Burning occurs when the solution temperature is below the minimum recommended operating temperature of 18 °C. |
Increase the solution temperature to within the recommended range of 18–25 °C. |
Incorrect plating thickness
|
Incorrect surface area estimated or calculated |
This is likely to be the most common cause. The measured thickness differs from the target even though the calculated amp setting and plating time were used. Irregular shapes, edges, recesses and multiple surfaces are easily underestimated. |
Recheck the total surface area in cm² and enter the corrected area and required thickness into the Yellow Gold Tank Plating Calculator. If you are unsure how to estimate the surface area, ask our Technical Assistant for help. |
| Temperature differs from that used for the calculation |
The calculated amp setting and plating time have been followed, but the measured thickness is consistently higher or lower than expected. |
Check the actual solution temperature and use the Yellow Gold Tank Plating Calculator with the appropriate temperature setting. |
| Agitation differs from that used for the calculation |
The calculated plating time has been followed, but the measured thickness differs from the target. |
Check that the actual agitation corresponds with the setting used in the Yellow Gold Tank Plating Calculator. |
| Brightener level has changed |
The plating time was calculated correctly but the deposit is thinner than expected. This may occur after adding Yellow Gold Tank Plating Brightener because the brightener reduces cathode efficiency and therefore reduces the deposition rate. |
Recalculate or verify the plating time under the actual working conditions. For thickness-critical work, confirm the finished deposit by XRF or deposited weight. |
Deposit is bright but rough
|
Particulate contamination of the plating solution |
The deposit retains its normal bright yellow-gold appearance but develops a rough or gritty surface. A common source is abrasive residue carried into the solution from the workpiece, particularly material trapped in holes, recesses and relief work. Dust from buffing and polishing machines is another major source of particulate contamination. |
Thoroughly rinse and inspect workpieces after polishing or abrasive preparation, paying particular attention to holes, recesses and relief work. Keep the plating area and solution protected from buffing and polishing dust. If contamination has entered the solution, filter it through suitable filter paper or use continuous cartridge filtration. |
Deposit is pitted
|
Gas bubbles reaching or adhering to the workpiece |
Small pits or pinholes appear where gas bubbles have contacted or remained on the surface. Gas is generated at both electrodes, with a substantial proportion generated at the anode. Excessively vigorous stirring can also draw air into the solution through the vortex produced by the stirrer. |
Use an anode bag as recommended for Yellow Gold Tank Plating Solution. The bag helps prevent bubbles generated at the anode from reaching the workpiece. Use medium–high agitation, but avoid stirring so rapidly that a deep vortex forms and draws air into the solution. Reposition the article if necessary to prevent bubbles becoming trapped in recesses. |
| Particulate contamination |
Pits occur randomly and may be accompanied by roughness. Particles temporarily adhering to the surface can interfere with deposition. |
Filter the solution and eliminate the source of contamination. Check especially for abrasive residues carried in on workpieces and buffing or polishing dust entering the plating area. |
| Grease or oil contamination on the workpiece |
Pitting or small areas of poor coverage occur despite otherwise normal plating conditions. Water may bead or pull away from contaminated areas during rinsing. |
Repeat the surface preparation. Degrease thoroughly, then use the appropriate Spa Plating cleaning/activation process before replating. |
Unplated areas
|
Inadequate cleaning or activation |
Gold fails to deposit in isolated areas, often with an irregular boundary. A water-break during rinsing can indicate remaining grease or contamination. |
Repeat the surface preparation, making sure the article is thoroughly degreased and correctly activated before plating. |
| Porous, deeply scratched or poorly prepared underlying surface |
The unplated areas correspond with pores, deep scratches, pits or other defects in the underlying surface. |
Mechanically prepare or polish the surface to remove the defects before repeating the surface preparation and plating. |
| Underlying metal is difficult to plate directly |
Plating is satisfactory on some areas or materials but consistently fails on the particular underlying metal. |
Check the Process Sequences tab and use the correct preparation and plating sequence for the metal being plated. |
Vertical tide marks
|
Gas bubbles coalescing and travelling up the surface of the workpiece |
Vertical streaks or tide-like marks form in the direction that bubbles travel upwards across the surface. |
Use a bagged platinum rod electrode to help control anode-generated gas. Adjust the position of the workpiece and agitation so that bubbles are carried away rather than travelling repeatedly over the plated surface. |
| Poor agitation pattern or eddies produced by the stirrer |
The marks occur in a repeatable pattern and may change or disappear when the workpiece position or stirring speed is changed. |
Reposition the workpiece or stirrer and adjust the stirring speed to produce good solution movement without strong localised eddies or a vortex. |
Deposit peels or blisters
|
Inadequate cleaning or activation |
The gold lifts, peels or blisters from the underlying surface during or after plating. |
Remove the poorly adhered deposit and repeat the surface preparation, making sure the article is thoroughly degreased and correctly activated before replating. |
| Incorrect preparation method for the metal being plated |
Adhesion problems occur consistently on a particular underlying metal even though the surface appears clean. |
Check the Process Sequences tab and use the correct preparation and plating sequence for the metal being plated. |
| Existing plating layer is poorly adhered |
The Yellow Gold deposit peels or blisters together with an underlying plating layer. |
Remove the unstable plating back to a sound, well-adhered surface before replating. A new Yellow Gold deposit cannot improve the adhesion of an unstable underlying layer. |
Platinum electrode becomes discoloured
|
Metallic gold has deposited onto the platinum electrode |
The platinum rod develops a gold, brown or darker discolouration during use. This is metallic gold deposited onto the electrode and is not detrimental to the functioning of the plating solution, provided the electrode is bagged. |
No corrective action is normally required. Continue using the platinum rod electrode with a suitable anode bag. |
