How to make Magnetic Fluid (ferro fluid)

Get the shirts: bit.ly/scishirts
In this episode we will show you how to create your own ferro fluid using oil, toner and a magnet.
Shopping List:
1. MICR Toner (Office Supply Store)
2. Rare Earth Magnet (Hardware store)
3. Vegetable Oil (Grocery Store)
Make sure you are subscribed for more Scientific Tuesdays!
Dylan's Facebook: / hacktheplanet __
Music By: Dj 700Degrees
Link: / dj700d .
.
Serious Business Inquiries Only: Contact us at: / householdhackertv (email address at the bottom)

[@IgnatianMystic]

The reason why this fluid is magnetic is because laserjet printer toner contains iron-ball ink (ink that contains dissolved iron particles). A laserjet printer contains a magnetized drum that the printing paper runs over, and the drum pulls the ink onto the paper in the pattern of whatever is being printed (a picture, a document, etc.). The iron in the ink is what makes it magnetic. TMYK. =3

[@mynameismaou]

thx for the fact dude :)

[@IgnatianMystic]

+Renzperi TheGamer ( > w 0)=b * crappy wink/thumbs up emoji FTW *

[@IgnatianMystic]

***** In theory, yes, although combining it with water or certain other fluids may render it incapable of behaving the way it does in this video when exposed to a magnetic field.

[@Volound]

+IgnatianMystic "reason" "why" and "because" all mean the same thing.

[@IgnatianMystic]

+Volound Don't lecture me on my grammar skills from a comment I made at 2:00 AM in the morning (if that even was the correct time... All I remember is that I was half asleep when I made that comment).

[@bakeyrecords8533]

Does anyone think that those needles look like the small things in big hero 6?

[@UltrasmashGP]

Yes

[@RatFurnis]

No

[@janiemartin5729]

.

[@daniaelgamal5112]

Omg yes imagine just imagine if they were and the power we had if that happened

[@lola9283]

Oh My God! Yasss i knew they looked familiar!,, This is AWESOME

[@eelcogg]

1. Pour toner into a cup 2. Sneeze 3. Sell the house

[@Superbudman]

LOL

[@mikoajjaros3570]

eelcogg Or bring it to the color day.

[@Chemicalbouillon]

^^ yo

[@funkid7080]

e

[@TheRandomizer44]

eelcogg ii

[@MyLittleMagneton]

Do you think it's possible to pair ferro fluid with an electromagnet, and maybe adjust the magnetic field based on music.

[@giovannilp03]

magic

[@TheDZHEX]

The inertia of the fluid might make it a problematic to move it very quickly, but it has already been done with metal dust.

[@davidwest7851]

That a good question

[@fail0ver]

Yes, planning to do this, but I am a bit worried about safety (toner is not exactly good if inhaled).

[@fail0ver]

***** Might not be enough to just mask yourself in the first phase, I am still waiting for additional information.

[@mietschj]

"Now comes the fun part: stir it." Yeah, that's definitely the most fun thing about ferro fluid.

[@lukasrizkalla3980]

lol

[@RajveeR.2007]

Lol old comment

[@mietschj]

@@RajveeR.2007 Lol new comment

[@RajveeR.2007]

@@mietschj Omg your fucking alive OMG

[@WooBear]

lol smh 1 week old comments

[@Whetzell]

For everyone who is NOT SPIKING it is NOT YOUR MIX. Test your powder before you apply any liquid. The powder itself will spike if it's the right formula. I have found that MICR only blobs (as a powder AND as a liquid) while pure IRON OXIDE POWDER spikes as a powder AND a liquid. I didn't even use a surfactant and it spiked amazingly! I hope this helps everyone!

[@violettbellerose1173]

So either you use the toner or the metal? You don't need to use both?

[@Whetzell]

I ended up buying the legit stuff because to REALLY make it you need to do some actual chemistry. The iron bits without liquid were much better than the toner but it's still not real ferrofluid.

[@violettbellerose1173]

+Jason Whetzell Ok, thank you very much n.n

[@MissClockwork]

I think they should be called "common earth magnets" by now

[@TopTributeBands-N-Stuff]

+Axtran Good point.

[@ragnarokinVII]

+Axtran Nah, they're still rare. Rare enough in fact that they have to try and find a way to make them artificially, because we'll be running out of them sometime in the relatively near future.

[@ethanromig5125]

+Ragnarokin I have 35 neodime magnets

[@Pxlsdr]

+Axtran The reason they're called rare earth magnets is due to the fact they are made from Neodymium, which is one of the rare earth elements.

[@zak8953]

+Axtran "Rare earth" doesn't mean rare. I realize that is confusing... The term is talking about a segment of the periodic table when they say "rare earth".

[@aurulious3472]

Rest in peace, Dylan.

[@deenp3761]

Whos dylan and how he die ?

[@razor11079]

3:09 That's a Penis

[@AlphaSteelFang005]

it sure is

[@gwenclark3701]

yup

[@gokuheroman]

lol

[@gwenclark3701]

yeah

[@gokuheroman]

i think many girls would be attracted to it

[@gayasaurusrex4301]

it looks like the stuff that made venom from spider man

[@azeem1597]

symbiote?

[@gayasaurusrex4301]

yes

[@zenect6555]

+Azeem Is Awesome i agree Azeem is awesome.. Look at my last name

[@azeem1597]

Asyraff Azeem lmao, hi 😂

[@geraldinewoods254]

its dose

[@musictrans]

Dear experts, Which oil you prefer to get maximum liquidity at normal temperature? Also what to add to look more silver? Thank you

[@AncucGaming]

Are there any "shiny types" of toner that can be used for this? For example, like a chrome colored one? (Yeah I realize this may be an idiotic question, since printers don't use that type of ink, but I'm asking either way).

[@MrNamegame]

Holy crap! This is just so cool....

[@yeaboiii3057]

if you want to put it into a bottle, what sort of suspension fluid would you use??

[@socketman]

I'm guessing water since the ferrofluid is made with oil.

[@Xeidasx]

have fun cleaning that up

[@wizenwashere1668]

Xeidasx just get an earth magnet and drag it into the cup its simple

[@aurorat4714]

This is very creative way of using ordinary materials that all school with or without resources to demonstrate magnetism concept. Great! Will definitely use this in my class.

[@beamaldonadodenabb1632]

Please help! I followed the instructions exactly the way you said in the video but the ferrofluid doesn't spike. What am I doing wrong?

[@foreal1518]

Bea Maldonado maybe you need a stronger magnet

[@animesenpai1163]

yeah mine Doesnt Work too D:

[@beamaldonadodenabb1632]

dat boi in the striped pajamas Thank you! I bought new magnets and still no luck.

[@beamaldonadodenabb1632]

【Karma Akabane】 - 【Anime-Lover】 It's a bummer! 😔

[@animesenpai1163]

Iam Trying To Find A Neodymium Magnet//Rare Earth Magnet ...cant find it in any hardware Stores

[@spongebobboxpants6808]

it looks like the stuff that the alien from district 9 was trying to make

[@apexjesus8369]

lol

[@spongebobboxpants6808]

+davi santos you get what I'm saying, right?

[@apexjesus8369]

+Saitama the one where people accuse you of fucking an alian because you're arm turned into one?

[@spongebobboxpants6808]

+davi santos OH SHIT! THE MNU AND GOVERNMENT IS ON TO ME! CHRISTOPHER, IS THE SHIP READY?!

[@hansgruber788]

This is the first stage of how the T-1000 was born

[@Mysticswagger]

TONER 1000 IT MAKES SENSE!!!!!

[@alecifitation]

I can't believe I've been watching your videos for 9 years! I was 13. How time flies.

[@JacobBpie]

What if you ingest it? Would it give you like metal bending super powers

[@ashleyfranklin5342]

you might have a sudden attraction to magnets lol

[@PhotonMaster101]

Sexually O.o

[@InsaniityDuck]

try it

[@tavoi1792]

Or you will simply get cancer, only the future can tell, you may transform into venom with cancer

[@JacobBpie]

***** i can only imagine it burning *shivers* i don't even want to think about it.

[@bradyrose]

I wonder if it would be possible to create a ferro epoxy and have the geometric shape cure in place.

[@merlijntoby8528]

That's an awesome idea.

[@kaeldare]

Well it would have to be pretty thin to start with but I think it is potentially possible with the right materials...

[@micahwilliamson7472]

kaeldare It's not that hard. I had a few tubes of epoxy and some extra materials and was able to make it happen. It really doesn't take any special materials.

[@bradyrose]

Micah Williamson I would really love to see some photos of some cured ferro-epoxy.

[@charleslawson7651]

Micah Williamson photos, or it didn't happen.

[@GaryKildall]

It's nice to see the magnetic field and cohesion of your toner fluid.

[@Jaeji]

wait can anyone show me a link where i can buy THIS toner? it keeps showing me these big toners.

[@kevinbaugh4147]

keyword is "laser bulk toner"

[@arjunasenvirathne3708]

great how does it work

[@schitlipz]

arjuna senvirathne Same principle as iron filings. The "field lines" are made visible by individual domains lining up with the field and simultaneously repelling each other (the raw field is contiguous rather than spikey).

[@muffin1820]

I wonder what happens if you pour the magnetic fluid all over your hand. And hold a magnet in your hand. :/

[@muffin1820]

Ayush Negi I already know that, Sherlock.

[@muffin1820]

Jeez bro. It's just a question. Don't be a drama queen.

[@eleos7771]

Ayush Negi Gremmer Nezi

[@eleos7771]

Of course you don't

[@doomguy2.0]

Ayush Negi shut the fuck up woman, stop your bitching

[@popcornhead6294]

Would make for an interesting magnetics lesson. Those little nubs following the magnetic field of the magnet is pretty cool.

[@Girl-Supersonicboy]

My science teacher would have been ten times cooler if her had done this back when I was in middle school

[@elroycheung8110]

Where u get toner

[@flapdoodel123]

office max

[@TornaitSuperBird]

Spencer Dunbar Or Staples

[@bailey125]

wouldn't that shit just stain everything?

[@zxma3679]

No stupid

[@bailey125]

Its printer ink, how is my question stupid?

[@zxma3679]

Oh so not squid ink

[@bailey125]

Lol wtf? Squid ink?

[@zxma3679]

unknown

[@SherkhaNO1]

Wow this is amazing and beautiful !

[@ThePurpleRoseWithAHedge]

Very cool. Question: Does the liquid act as a magnet as well? Example: Like attaching a paperclip to the spikes?

[@javascriptsophie4958]

I made this and it's so cool! It's also very fun to play with :D

[@trealexander5271]

if I used a high power electro magnet would it float?

[@monochromatic2987]

Maybe.... You should try that

[@AppleNewspaper]

Yes it would my boss and I were cleaning out the old lab at my work an I had seen your comment and I tried its wicked cool

[@trealexander5271]

That's awesome

[@davemwangi05]

@@AppleNewspaper did it float?

[@illmounturmother]

One of the first videos ive watched...

[@itsMayama]

COOLEST THING IVE EVER SEEN!

[@watercobragaming]

can u add like food coloring for different colors

[@Thebravekitten66]

Considering its black I doubt it. With a different color toner ink maybe?

[@CairnOwO]

+Thebravekitten66 Jet Black toner has iron filings in it for the color, that's what makes it magnetic

[@Thebravekitten66]

weredragon100 Ah I see. Thank you.

[@rileysch8888]

How do you color it if it's black?

[@JUDD3R2]

+Riley S it's really as simple as, just use or mix any colour toner to your desired colour.

[@Drestopmotion]

Is it toxic?

[@BabyHoldingGun]

most likely, the fluid has toner in it

[@GiacomoBotti]

it's iron filings with oli

[@SkittleDash]

probably not really toxic, since toner is just "plastic" (but I wouldn't dare)

[@SkittleDash]

in that case it'd be even safer, since we are used to iron, and we literally can't live without it.

[@johnsega9734]

euh.... no.... -.-

[@amourdoctrina9435]

My students loved this experiment in 2013. We'd use the recycled toner drums.

[@stolipuff7]

How to make a t-1000

[@arturonavarro5744]

Yes I have been looking for a comment like this join me as usTerminator fans united

[@bernithherting5954]

+Obsidian Samuri kil

[@danielzaba9913]

+Obsidian Samuri No, how to make a scrap house-made t-850 robot, for defense purposes.

[@nawneesavage5311]

what happens when you drop the magnet in the liquid

[@hahoang6693]

Have a very easy question here , because my english is not that good. Is toner ink ??? please help me i need to make a birthday present for my dad.

[@timdevisser4947]

yes I think so

[@nguyenhuy-nf2vx]

Mực đen in giấy ạ

[@suk4honesty]

it is ink you use in a printer!

[@andrewdescant]

No toner is a powder made from iron oxide and colored plastic. If you are trying to make something that reacts to magnets you can't use ink. If you look online you can find black iron oxide. This will work better than toner because it's all iron oxide and no plastic. Just don't buy red iron oxide.

[@ethanromig5125]

yes it is ink

[@scottdustman6394]

I've been trying to make this fluid for a while now but all I get is a blob with some tiny spikes...nothing like the large rounded spikes you show in your video. I've tried different toners and developers with strong magnets. Did you use some kind of surfactant? Is there something else that you added? Any help would be appreciated.

[@TXstang347]

Did you ever get it to work? Mine was just a blob. I've already tried cooking acid, toner and ammonia and that didn't seem to work either

[@GodSpeed1105]

Where do u get jet laser toner from?

[@Artulin]

Wait what do you mix again? Vegetable oil and what?

[@DakotaFlower]

Toner. The ink from laser printers.

[@justicek782]

You know you could have just went back in the video and listen to what he said. Instead of waiting for someone to reply 2 days later.

[@alisongrace4334]

Justice Kimmey marvellous grammar

[@striekr13577]

Alison Grace not you though

[@officialspyer]

Does the ferrofluid react to being placed on a speaker (covered by a blanket or something, I´m not that stupid)?

[@ethandagamer255]

maybe, but oobleck works better. :-)

[@derultnerlp9319]

+TheSpyAmongUs for that you need to mix water and potato starch ... when its thick enough it will bounce when music is played

[@IcanSPELLmyNAMEOG]

+TheSpyAmongUs You're thinking of non newtonian fluids.

[@MrRoomba2321]

like cornstarch and water.

[@poonamgupta-ej7uk]

Can we use printer toner on the place of micr toner or not? Sir please reply . It is very urgent.

[@zoeyls6296]

That is sooooo cool liquids can turn into solids now

[@MrGriffinsShorts]

I see what you did there :D 3:00

[@natemotionstudios8631]

Im glad i wasnt the only one

[@QuickzLXI]

Rating: "No mature content."

[@daman7387]

Could you stick this stuff to your fridge?

[@samspence687]

da man Sadly, you can't. It would only work if the fridge was magnetized, which would make fridge magnets redundant, as people would just put regular metal (which should contain iron, nickel, or cobalt) on the fridge to hold things up. p.s. - this is the first legitimate question i have seen in the youtube comments section of a video

[@daniellyle6659]

Sam Spence omg ikr

[@fershred]

Sam Spence but you can freeze the ink next to the magnet so it keeps that shape, and then cover it with something like nail polish

[@TheNoiseySpectator]

+Fer Shred That is a fascinating idea! Have you tried it? Does it work?

[@fershred]

TheNoiseySpectator I don't even have a printer lol

[@WilsonsPAC]

Can you use magnetic paint instead of magnetic ink?

[@Sonicfan138]

This video is five years old today. Happy birthday video!

[@ndbd9drn]

Why is the toner you used in a bottle? I can only find cartridges!

[@aperson4075]

Dunno

[@ivandamico93]

The toner you want to find is for office photocopiers, not laser /bubble jet printers, and can be found at office supply shops or online

[@bmkorkut]

+Norina F You might look for toner refills

[@linkcowgamergameplay]

Ikr

[@Rockband2991]

+Norina F not printer toner

[@T3hub3r1337]

True ferro fluid won't stain the way a toner based one will.

[@jpmac098]

yes it will.

[@T3hub3r1337]

Clearly you've never been in a lab with this stuff. The high grade fluids are held to much tighter specifications.

[@jpmac098]

darkwarrior well no shit I haven't been in a lab with ferrofluid. It's not an every day thing for most people. "True" ferrofluid generally stains things. Pure ferrofluid might not, but "true" ferrofluid is anything that is technically ferrofluid. Besides, I have seen the stuff at the arizona science center and it still stains things. And I actually just got a jar of the stuff suspended in vegetable oil (really cool toy) for christmas. Merry Christmas by the way :D

[@T3hub3r1337]

Aye, wish it coulda been a little smoother to be honest. Could be worse though. So thankful it wasnt i suppose. Suspensions are always cool. But i REALLY love the tables of ferrofluid, long spiral spikes and cones and all that with thousands of different ways to set up the magnetic field literally millions of possible shapes and motions you can make with em. The lab grade stuff lacks the compounds that will cause stains, unfortunately this process also makes it hella expensive, i was lucky enough to be in a program where i got to see alot of cool things, UV Co2 lasers melting bricks into molten glass? Fuuuuuuck yessssss. So i guess my view on it is kinda skewed. This stuff was fresh off line cutting edge tech when i first saw it. So i suppose easier methods (although dirtier ;D) have been developed. All a matter of what you pay and how much you care about keeping stuff clean.

[@jpmac098]

darkwarrior That sounds really awesome. I actually just had an idea while playing with the stuff of making a table out of it. I might try that... It would be heavy as hell but totally worth it to have a coffee table made of glass with ferrofluid suspended in it. Hmm. Maybe next Christmas lol.

[@tracycousins2584]

this is so cool i want to make a lamp of some sort with this

[@richardcline6575]

what happens if you put ferro fluid in oobleck and put a magnet inside?

[@MrEclipseHeart]

We are working on black liquid ? ohh lets use a black table as well

[@MrEclipseHeart]

What that has to do with my comment? wow think twice before replying are you trying to act like a smartass or something?

[@kikikikoboy8363]

***** Decreased*

[@LetoZeth]

Cian Palowitch Perhaps in your case.

[@jonathancw2948]

For some reason, ferro fluid is one of the reasons I'm developing Trypophobia.

[@owenhaughton1047]

whats that

[@victortarcena3568]

Tripophobia its from holes not from spikes

[@holyngrace7806]

A really good way to demonstrate magnetic lines of force! Brilliant fun!! Some friendly advice. Toner powder is a definite health hazard and should be kept contained. If it must be handled then a risk assessment should be made first and precautions such as mouth and nose mask, eye goggles and disposable gloves ought to be used as a minimum. Despite appearances it will disperse into air eddies with the microscopic particles then getting into the skin, mucous membranes and respiratory tract. Similar level of hazard as asbestos.

[@techtronicman1]

Is it possible to have that harden into a crystal?

[@pretzel502]

Not with regular ferrofluid

[@sciencevetal]

Cool)

[@marliforten]

Cool

[@ara_n]

Cool

[@gnaneshp5426]

Pretty cool huh!

[@muhammadrafiquedarwisy8012]

Cool(

[@wordswype3934]

Don't want to be a geek or anythin, but at 1:16 it's not a jar. It's an Erlenmeyer Flask. just sayin

[@thewalkingundead]

aint nobody got time to pronounce that out ! :P

[@nicholasperry7990]

If this material was to be put into a contained space, mounted on a wall with magnets on the back would this same effect work if the liquid was held at a vertical? The space would be a 1/2 inch in depth rectangle.

[@DanBowkley]

Plain old laser toner would work fine; toner is just finely powdered thermoplastic and finely powdered iron. In the printer (or copier) a magnet right in front of the imaging drum attracts the toner and basically acts like a brush, gently transferring the toner powder onto the rotating drum without scratching it.

[@larrparks]

i ate it

[@lootziedoodle]

How can you eat liquids?

[@qweqw916]

Wadan Popal Good question

[@jawadaslam1000]

You ate or hate

[@stevensanchez1192]

Am I the only one who started wondering what would happen if you stuck a magnet onto his stomach?

[@catphisch7629]

cheers

[@Nasa1ish]

i am just watching this video and never try iy

[@nolanrudolph5463]

Wait, let me pick up some laser jet toner from my local shopping center before I start...

[@Nailnuke]

So pretty cool looking, but does it have any use ?

[@UltraBoyII]

it didnt work for me

[@nonohate]

Or check your local HDD

[@samantharosee_xx6810]

He's made so many monster-looking goos that he could have like, an army! XD

[@nekochase760]

I was waiting for you to touch it. I was impatient until you touched it and Im like "My mission is a success"

[@jedrzejwysocki5584]

3:00 "As you can see - I can draw with this" Am I the only one, who noticed, that drawing of a peanuz? :>

[@spaceman323d]

splatatatatatoon

[@nabeehasufian6]

AWSOME! I WISH I COULD TRY IT BUT WHERE I LIVE, THEY DON'T HAVE THE SUPPLIES

[@shadowarkn1942]

OMFG THIS IS THE MOST AWESOME THING I EVER SEEN

[@didhedied9632]

how can this video have over 45 million views when theres only 7 million ppl on the planet o.O

[@ha-jongjhun7943]

there 7 billion people not million

[@kamoc231]

tayyib shahid he's stupid but you can't spell... Sad sad world. Wal-Mart has a sale on dictionaries. I might consider buying one dumb ass. Or paying attention in English class.

[@ha-jongjhun7943]

Are u seriously thinking that there only 7 million people on earth

[@sargasm169]

Ha-Jong Jhun Are you seriously thinking?

[@JJtoob]

Typical troll bait.

[@juliag1097]

Wow. At Vat19.com, you can but "Ferrofluid in a Bottle" for up to $50! I'm so glad I didn't buy it...

[@whendaybreaks4317]

They don't make it out of vegetable oil over there mate.. And the ferro fluid is encased in a special concoction to keep it clean. It is a lot more high quality than this.

[@jennjennifergarcia]

Hey I have a question. How would you properly dispose of the ferro fluid? I believe that if i pour it down the drain it can lead to pipe damage. So how would I dispose of it?

[@cgStarling]

@franklin flores I guess you werent paying attention when he told you exactly where you can go to buy the magnet, obviously showing that they dont expect you to have it laying around.

[@NONAME-hy1xb]

Awesome how does it spike up

[@sabastiondowns8684]

Did anyone get the spiking effects he did with his procedure?

[@georgestanciu5466]

Very nice experiment. A silly question: can this fluid be used as transformer core?

[@philiphall7102]

This may be a stupid questions but. is MICR Toner in other colors? and if so does those colors work too?

[@llamabean7353]

thats like the coolest thing iv ever seen

[@bmkorkut]

Is this mixture durable? Does it become heterogenous or dissolve after a while? Can it be used in a project that is expected to last?

[@davebolig1989]

new versions of toner are made with polymers. These are types of plastics that produce a better image. This guy was probably using old toner that uses iron oxide in it.Thats the stuff that's magnetic and gives the properties desired.

[@defcon9998]

What is the best way to clean this off your hands? Also, if you touch the spikes does the color get on your finger?

[@zombieslayerOFdeath]

What if you kept moving it around till there was no liquid left? Like the less magnetic liquid would stay behind and would you eventually end up with a powder? Or?

[@8bitjunkie173]

does it mix with water, if not, put in glass jar, put in water, looks awesome

[@audreytan302]

Hi may i know if the spikes are painful or solid? cuz i see on some websites it actually looks really sharp, but in your vid, you touched it...

[@sybvn]

Hi, I understand that not all toners can make the ferrofluid spike, can you please tell me where exactly you bought the toner, I cant find the exact toner you used in this video on internet!

[@ash_cyan]

what happens if we mix this fluid with ooblek or non Newtonian fluid?

[@yourboi1842]

Good question

[@jason-vm7my]

oobleck is non newtonium fluid, we can call it either way tho

[@filgo2323]

If you leave it in a cup with the magnet on it, how long will it stay in the spiked ball form?

[@why-cz4hz]

Just wondering, could you just break open one of those kid's toys with the scraps for magnet stuff in them and mix it with some ink/iodine?

[@StreakyBaconMan]

If you have any old or broken hard drives you can get a neodymium magnet from it that should be a decent size, and I have even had some hard drives which have 2 of them. Older hard drives seem to have larger magnets for some reason in my experience so the older the better. Be careful with the larger ones, because they are extremely powerful. I broke and cut the tips of two fingers when two larger sized neodymium magnets snapped together when they got too close to each other. Also be careful where you stick your magnets, more than once I have got one stuck on a flat surface that I cannot get enough leverage to remove the magnet.

[@Shotindahead]

Could it be possible the various landscapes we have are caused by the different magnetic poles i.e. Mima mounds in washington state

[@James1toknow]

You can actually use it to cool parts that may not have oil pressure and keep the oil moving and cooling and returning to cool the part. Interesting!!

[@TrangTran-eo6ck]

love it were did you buy that ink😻💥💫🌟💫

[@ElliotGarbus]

yes please let me know. Having hard time finding the ink

[@c0mplex956]

Does it matter how strong the magnet is? Is a magnet with a pull force of 40lb enough?