Ted Mooney, P.E. RET
- Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
-----
What is a Hull Cell Test, Why is it done, Where to Get a Hull Cell
Quickstart: A Hull Cell is a tiny (267 ml) electroplating tank used to plate test panels rather than actual parts. Viewed from a bird's eye, the tank is trapezoidal, with the test panel close to the anode at one end and far from it at the other end, so the effect of plating at different current densities can be clearly seen, helping the user figure out what is wrong with the plating solution or needs adjustment.
The size of the cell was chosen to simplify "scaling up": a 2 gram addition to it is equivalent to 1 oz/gallon in the main tank.
There are many suppliers, and Hull Cells, test panels, & accessories are available online
⇦this on
eBay
or
Amazon [affil links] .
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RFQ: We are looking for a Hanging Hull Cell. We have many in our shop that we purchased from McGean & Rocho, but they are no longer in the business. Please help if you have any suggestions for new or used equipment. Thank you.
Mary [last name deleted for privacy by Editor]Plating shop - West Springfield, Massachusetts
2003
Ed. note: Sorry, this RFQ is outdated so private contact is no longer available, but public technical replies are still welcome!
RFQ: I want to buy Hull Cell Tester but I don't have any specs or part number at present; can you please assist?
Thanks,
- Clarkfield Pampanga, Philippines
2003
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
A. Hi May.
It's possible that all you are looking for is a standard 267 milliliter cell
⇦this on
eBay
or
Amazon [affil links] . You may also need a small rectifier (power supply), and/or a heater to maintain correct plating temperature. But there are also modifications like hanging cells, jiggle cells, double-size cells, etc. If you tell us what kind of plating you are doing, readers may be able to help you further regarding those specialty Hull Cells.
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
RFQ: Please give specific supplier for Hull Cell equipment here in China.
Thank you. Need it very urgently.
- Zhuhai, China
2005
Ed. note: Any supplier is welcome to advertise here and get their name up in lights, Joseph, but we're already absolutely drowning in spam from suppliers who want to advertise here for free so, sorry, we can't encourage it by letting suppliers suggest themselves.
"The Demand Curve for internet advertizing:
Infinite demand at zero cost, zero demand at infinitesimal cost "
-- Thomas J. Pullizzi, co-founder of finishing.com, 1995
RFQ: I am new in electroforming process and lately I encountered problems with nickel baths. I want to learn which methods can be used to test the contents (any contamination, etc.) of the baths and which information I can get by carrying out Hull Cell tests for my nickel sulfamate baths.
Does an electroformer really need that piece of equipment? Right now, by simple titration, I determine Ni++, Cl-, and boric acid concentrations of the bath. Any suggestions about those concentrations? And also any suggestions about Hull Cell test equipment suppliers in EU or USA? Thank you for your replies already.
Limec I [last name deleted for privacy by Editor]plating shop - Berlin, Germany
2005
Ed. note: Sorry, this RFQ is outdated so private contact is no longer available, but public technical replies are still welcome!
A. Hi Limec. In my opinion, and the opinion of some industry icons a lot smarter than me, everyone doing any plating needs a Hull Cell for three reasons that I can think of offhand.
Firstly, and this one may apply less strongly to nickel electroforming than other plating, a Hull Cell lets you see what will happen at very high and very low current density in case a part you are making will require plating in that range.
Secondly, it helps you spot trends before you make defects -- if the good plating range is declining from one Hull Cell test to the next, you have advance notice that the problem may soon extend into the current density range you are using.
Thirdly, and this applies to everyone doing any kind of plating, you should never make additions to your tanks based on theoretical calculations. Rather, you should do the theoretical calculation, make adds to the Hull Cell ... and only after you have verified the results of the add do you go on to scale it up to bath size.
Hull Cells are available from many suppliers
⇦this on
eBay
or
Amazon [affil links] , but as previously noted, we're drowning under spam (over a thousand e-mails a day interfering with our effort to post technical Q&As), and we can't exacerbate that problem by rewarding it.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
RFQ: I am in need of a couple cadmium hull cell anodes to fit a 267 ml hull cell.
[adv: panels on
eBay
or
Amazon [affil links]
Plating Chemical Supplier - Bedford, Ohio
2007
Ed. note: Sorry, this RFQ is outdated so private contact is no longer available, but public technical replies are still welcome!
Current RFQs are on our "Hotline" page.
The mathematics of Hull Cells
Q. For Hull Cell I need an equation to find current density at different distances of cathode.
HECTOR LONGUEIRA- ANTOFAGASTA, II region, CHILE
2004
A. Hi Hector,
This is the formula to calculate current density for a Hull Cell panel.
c=i(5.1-5.25logx)
c= current density
i= current applied
x= distance to be measured on the panel (panel side close to anode is HCD area and side away from anode is LCD area)
- Kitchener, Ontario, Canada
Q. Dear Sr. :
I have two questions about Hull cell :
Using the current density equation of the Hull cell ( C : I ( 5,1 - 5,25 log x) ), there are an infinite currents that might be used (usually described as 1, 2, and 3 A ). I Need to evaluate additives between 200 and 500 Ampere per square meter.
Q1 : Which current should I work with the hull cell.
Q2 : What time of deposition should be use.
Sincere regards.
Peter Holmes- Antofagasta, II Region, Chile
2004
A. It might help if you would tell us about the plating bath you want to evaluate ...
James Totter, CEF
- Tallahassee, Florida
A. Dear Mr. Holmes:
You need to be more specific in your question.
Hull Cell can be applied to many electroplating processes, with different purposes.
- Santiago, Chile
A. Applied current and testing time all depend on what you are testing in the Hull Cell. There are set conditions for different plating systems, details of which can be found in any reputable book that discusses the Hull Cell. Try The Canning Handbook [on eBay, Amazon, AbeBooks affil links]. No one can answer your query unless you say what you are doing.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
Q. How do you read the hull cell ruler?
⇦this on
Amazon [affil links] It is stated from the ruler that it has 1, 3, 5 Amps. how much time should you use? 1 min or more?
We are currently using SnPb chemistry for IC packaging. I'm a bit confused as to how to read the ruler. I'm currently using 3 Amps 2 min. when I read the result using the ruler, I use the 3 amp portion and multiply the Current Density by 2 -- is this right? We are using 10-20 ASD meco plating machine.
I hope you guys can answer this question the soonest. Thanks in advance!
2005
semiconductors - Laguna, Philippines
A. Hello,
Hull-cell current to be employed depends on the type of plating you are investigating and the average current density and maximum operating current density you are likely to encounter in the production tank.The purpose of the Hull cell experiment is to know the plating quality at different current densities in single test. Generally, for vat plating it is customary to use 5 amps and 10 minutes to get the test result. 5 amps will give a range of 0-200 amps/sq. ft current density.This range, I think, will be sufficient for most of the decorative or commercially useful applications.
Good Luck!
Subramanian Ramajayam
consultant - Bangalore, India
December 19, 2011
Q. Dear sir/ma'm
I am pursuing research in alloy electrodeposition. In this regard I would like to know the theory of 267 cc Hull cell equation c = I(5.1-5.24logx) in terms of either simple mathematical simulation or trigonometrically.
Research scholar - Rajapalayam, Tamilnadu & India
September 15, 2008
A. The Hull Cell was invented by RO Hull and a paper was published in 1939 by him about it. I suggest you track down this paper as it may well describe the mathematics behind the system. There is also a book called The Hull Cell by Walter Nohse [on
eBay in English,
Amazon in English, &
AbeBooks in original German affil links]
; this was published in 1966 by Robert Draper, Teddington. Again this may well contain the math you require.
The actual math is quite easy to work out once you have understood the principles of the cell, but it is made even easier by computational modeling; so if you cannot track down the above texts, you may want to attempt solving it yourself.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
A. Try this site: www.springerlink.com/content/x118154920626732/ ⇩
for "Primary current distribution in the Hull cell and related trapezoidal geometries". Quite possibly deeper than you need.
Jim
- Navarre, Florida
Ed. note Oct 2020: The sprinkerlink.com domain no longer exists, but the article is available at springer.com as link.springer.com/article/10.1007/BF01030192. It's $39.95 in this age where we've chosen to make billionaires out of middlemen :-) ... but maybe someone will sell you that whole Issue 22 of the Journal of Applied Electrochemistry 1992 for 50¢ or so :-)
Q. Hi all,
I've been using a hull cell to evaluate the best plating parameters for a sulfuric acid copper chemistry. I now have the ideal additive ratio and current density but how do I figure out the current density of my piece in my larger plating bath. Also in my bath the anode-cathode separation is much larger than the hull cell.
Is there a rough equation for determining the current density at a point x distance from the cathode? Or do I just have to play with the settings?
Any help appreciated,
Thanks,
David
Student - Ireland
September 22, 2008
A. Hi, David. Figuring the average current density should be no trick. You just divide the total amperage by the surface area of the component, and it doesn't matter what the anode to cathode spacing is. The current density will vary across the component -- highest at edges and corners, lowest in the middle of expanses. Anode to cathode distance matters for this, but probably not at much as the geometry of the part. Software is available for modeling current density across a part but it's not a trivial calculation and more likely involves finite element analysis.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. When using Hull Cell the volume utilised is quite small and depletion of metal and or brighteners occur at a surprisingly high rate.
It's a good idea to use a perforated cell in a larger volume of electrolyte so that the electrolyte remains relatively constant.
Mel Platt
geriatic mel - Maidenhead, U.K.
November 11, 2008
A. The Hull Cell is an excellent tool for determining how an electrolyte acts under different current densities. The current density at any particular point on the Hull Cell plate will be dependent on the current applied to the cell, and there are standard Hull Cell tests that will tell you these values. When transferring this information to a real plating cell, the difference is that the anode-cathode distance should be the same for as much of the plating part as possible, otherwise you will get differential plating rates. Once you know the optimum current density for plating from your Hull Cell test and have calculated the surface area of your plating part in your larger tank, you can work out the total current you need to apply to your part. In practise, the greater the anode-cathode distance, the better the thickness distribution will be.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
November 13, 2008
Q. Hello Sir,
I am doing my deposition of copper using Comsol Software. How can we convert the current intensity in terms of dm^2 ?
- Furtwangen, Germany
April 15, 2012
[editor appended this entry to this thread which already addresses it in lieu of spawning a duplicative thread]
Q. Hello,
I am a student in chemical engineering and I am doing research on Hull Cell Testing.
And I need information on how it works, like the operative methods, and how to analyse the results, so if you can write it to me or give me some links about it, I will be very thankful.
Thank you
- Paris, France
April 23, 2014
A. Hello Jack. We appended your inquiry to a long and interesting thread on the subject. So please read it and think about what you would like to research in particular, then ask a specific question and we'll try to help. Good luck!
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Try Larry King Corp. I did business with them for years. They sell the cells, the flat panel cathodes, and anodes.
You can make your own 500 ml Hull cell. I did. Check out the dimensions and get the plexiglass pieces cut. Plexiglass is easy to join with solvent cement.
Dave Wichern
Consultant - The Bronx, New York
March 29, 2017
Q. In a Hull Cell can I use as a cathode a part (not flat) that needs to be coated?
Julia Savchenko- Austin, Texas, USA
March 28, 2017
A. Hi Julia. Sorry, no, a Hull Cell is terrible as a general plating tank :-(
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. The part that I need to coat is magnet NdFeB; can I use cathode made out of NdFeB in a Hull Cell or in a Rotating Cylindrical Hull Cell? Thank you!
Julia Savchenko [returning]- Austin, Texas, USA
A. Hi again, Julia. I guess you're not asking about a hull cell as a testing device but as a small general purpose electroplating tank for your magnet.
It's not ideal for that for a few reasons, including the fact that a hull cell is designed to plate only one side of an item rather than both sides. I think you'd be much better off using a glass beaker [beakers on eBay or Amazon [affil links] so you can put an anode on each side of the part and so you can easily use a hotplate/magnetic stirrer ⇦this on eBay or Amazon [affil links] for agitation. Good luck!
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Thank you very much for taking the time to answer my questions.
Julia Savchenko [returning]Urban Mining - Austin, Texas, USA
A. I would use a plastic polyethylene shoebox as a plating tank.
I'm not clear on what is being plated here. I was plating Cu and I used 3/8" copper tubing as anodes. I flattened little sections at one end, drilled holes, and joined them to the mickey mouse "busbar" with brass screws. Worked fine.
Ni would be tougher. Anodes there are generally Ni "crowns" and you would have to have some kind of conductive anode basket to contain them.
Dave Wichern
Consultant - The Bronx, New York
Q. Hello, I'm about to start an experiment about analysing the thickness distribution of an electrolytic bath, I'm looking for information about different cells that I could use in the lab, but can't seem to find information about cells other than Hull. Does anybody know where I can find this kind of information, or suggest any cell suitable for this experiment?
Thank you in advance.
- Sonora, Mexico
November 1, 2017
A. Hi Ricardo, there are many styles of Hull Cells including perforated hanging hull cells (for use within a plating tank), double size (534 ml) cells, 1000 ml cells, and "jiggle cells". There is also a different kind of test cell called a Haring (search the site) or Haring-Blum cell which is used to measure throwing power; which can be used for thickness distribution measurements as well.
But it seems to me that a Hull Cell is the ideal tool for thickness distribution determinations. There are youtube videos specifically about this; here is one courtesy of EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser]...
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hello,
I have a Hull cell in my lab (around 267 ml cell, I think). I am trying to perform Hull cell tests with some nickel baths. My Hull cell plate has an immersed surface of 50 cm2 (5 x 10 cm). My bath works at 1.5 A/dm2. How many amperes should I use : 1.5 x 0.5 = 0.75 A. Is it correct? I have seen that we should use 1, 2 or 5 A with use cell (as noted in many hull cell ruler). What is right?
Another question, I have forgotten my Hull cell ruler
⇦this on
Amazon [affil links] . Is it possible to draw/create my own Hull cell ruler? How to do it? Could you help me please?
Thank you in advance
Best Regards
Thomas
- Berne, Switzerland
May 25, 2020
Hi Thomas.
adv.
Download the EPI Finishing Utility app and you'll have your ruler, plus other stuff :-)
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hello,
Thank you Ted for your reply! This app looks great but unfortunately impossible to download it on my phone or tablet: This app is not available in our country :(
I will try to construct my own Hull scale. If someone can help me to construct my Hull scale, let me know please. I need to know the current density distribution on the Hull cell pate. And about the current to use, can we use whatever we want or is it advise to use 1, 2 or 5 A as specified in the Hull cell ruler?
Thank you in advance
- Berne, Switzerland
A. Go to google.com - images - and search for hull cell ruler pdf and you will get a lot of choices. Even in the restrictive climate in the EU that shouldn't be a problem.
Tom Rochester
CTO - Jackson, Michigan, USA
Plating Systems & Technologies, Inc.
Q. Hello,
Thank you Tom for your suggestion! Good idea, I had not thought about it!
I saw this formula in this thread :
c=i(5.1-5.25logx)
c= current density
i= current applied
x= distance to be measured on the panel (panel side close to anode is HCD area and side away from anode is LCD area)
What are the units in this formula?
Do you think I can use it to construct my own Hull cell ruler? But with this formula, current density will be infinity at x = 0, possible??
Thank you,
Best Regards
- Berne, Switzerland
June 4, 2020
A. Hi Thomas. I don't have the reference which offers that equation, but it seems to be more of a "curve-fitting" formula than a derivation based on first principles.
Current density is most often expressed in A/dm2, and it must be in this case because were it measured in A/m2 or A/cm2 the current density would be 100X lower or 100X higher, and that sounds unreasonable.
Since a Hull Cell panel is 10 cm long, and log10 = 1, x must be measured in centimeters. At a current of 1 amp then,
CD at 1 cm from HCD end is 5.10 A/dm2
CD at 5 cm from HCD end is 1.43 A/dm2
CD at 8 cm from HCD end is 0.36 A/dm2
CD at 9 cm from HCD end is 0.09 A/dm2.
My limited understanding is that the formula is considered valid and usable only between 1 and 8 cm from the HCD end, so the fact that log0 is undefined and approaches negative infinity doesn't matter.
Luck and Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Hello,
Thank you Ted for your comments! I will try to construct my own Hull cell ruler with this formula.
Best Reagards
- Berne, Switzerland
Q. Hi, I don't see anything on this thread about chrome plating hull cells. I have a chromic acid plating bath that I would like to track with a hull cell from time to time. We have one onsite, it's poorly constructed, doesn't seem to be a standard size (267 mL, for example), and doesn't have a heater. It's made of porcelain, I believe. Are there any other materials that can be used for chromic acid? Can you recommend a chromic acid hull cell? It would also be helpful to be able to heat the solution in the hull cell.
I am also wondering what the best settings for running a chrome hull cell would be -- run at room temperature for consistency? 5 amps? 10 minutes?
- Eau Claire Wisconsin
October 20, 2020
A. Hi Paul. I have no hands-on experience with hull cell testing, let alone for chrome plating, but you must run it at operating temperature, not room temperature. My understanding is that a perforated hull cell is suggested for chrome plating because of the otherwise fast temperature rise.
It seems that one approach is to hang a porcelain perforated cell in your chrome tank, whereas another approach suggested & offered by www.yamamoto-ms.co.jp/en is to place the 267 ml perforated hull cell into a 1000 ml enclosure tank -- I'm not sure of their material of construction but I don't think it's porcelain -- lots of plastics are sufficiently resistant to chrome.
Although there are guidelines for how long to run hull cells, in your case of decorative chrome where plating times are typically in the 30 sec to 2 min. range, I would think you would want to run it for the same amount of time as your plating time the first time around to get a feel for coverage; 5 A sounds right..
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hello everyone!
i was wondering if is there a way to measure or determine the Throwing Power Index of my electroplating solution with a Hull Cell or what's the specification to develop my own Haring Blum Cell??
Thanks in advance
-Sinaloa México
December 4, 2021
A. Hi Jorge. To the best of my knowledge the Haring Blum Cell has no special dimensions, just the ability of the anode on one side of the cathode to be 5X as far from the cathode as the anode on the other side. The article "Throwing Power Measurement: The Assaf Cell" ⇨
gives some good history and formulas.
But yes, you can calculate throwing power from thickness measurements on a Hull Cell panel. EPI offers a youtube video on how to do it.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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