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Finally... => Life Advice => Topic started by: Sappho on January 03, 2016, 08:14:35 am

Title: Cleaning a really nasty old oven
Post by: Sappho on January 03, 2016, 08:14:35 am
A friend of mine gave me his old oven. It's not a built-in one; it sits on the countertop, but it's quite big (not a little toaster oven). It works great, but it's about 10 years old and it's never once been cleaned. Worse, he had it in a nasty, dank, moldy basement apartment for most of those 10 years. It was sitting next to the cooktop and one side is completely plastered with ancient grease stains. The glass window is totally brown and black, and the inside doesn't look any better.

I just spent an hour trying to clean it, using the strongest cleaner I could find (and a good pair of rubber gloves). The water quickly turned brown and had to be replaced many times. I managed to get some of the gunk off, but a lot of it simply refuses to budge. I spent ten full minutes doing nothing but scrubbing the glass with the strong cleaner, alternating between a tough sponge and steel wool, and I can now see through it in some places, but a lot of it just won't come off no matter what I do.

Is there any chance I'll ever get this thing looking like new? I don't mind spending some time and some elbow grease getting it looking nice, but I just don't know if it's possible. My grandmother visited me and was horrified by the sight of the thing (she honestly believed it was a health hazard). Anyone have any oven-cleaning tips? Any specific cleaners (or types of cleaners - a lot of the things available in the US/UK, for example, don't exist here, so I need chemical names) that can take off the worst of the ten-year-old baked-on gook?

EDIT: Because it's been mentioned several times, MAGIC ERASERS ARE NOT AVAILABLE WHERE I LIVE. I do know about them but I can't get them here.
Title: Re: Cleaning a really nasty old oven
Post by: NullForceOmega on January 03, 2016, 08:56:44 am
I don't have any specific tips regarding cleaners, but as a general rule, when you've got old caked-on stains, multiple thorough cleanings tend to be helpful.  Once you've removed the outermost layer, you let it sit a while (at least until dry) then start again, repeat as needed.  It can be extremely time consuming to clean up neglected items like this, but it should be possible to get fully clean, unless it has suffered oxidization of it's main components.
Title: Re: Cleaning a really nasty old oven
Post by: martinuzz on January 03, 2016, 10:31:41 am
they do have those really strong kitchen appliance cleaning sprays nowadays in most supermarkets. They work wonders when you first wet the surfaces to be cleaned with hot water, let that soak a bit, then apply the spray. Most important, give the spray time to work. Don't immediatly start scrubbing, but let the spray soak a few minutes. Then scrub with as hot as possbile water, without burning yourself.

Also, if it has any detachable parts, it might be worth bathing those in hot solution of sodium carbonate in water. This will dissolve grease and oil stains or at least soften them up for cleaning. Age old domestic household trick for cleaning caked and crusted stuff from pots and pans.

And yeah, what's already been said: You probably will need to repeat it a few times.
Title: Re: Cleaning a really nasty old oven
Post by: DJ on January 03, 2016, 11:22:37 am
Tried paint thinner?
Title: Re: Cleaning a really nasty old oven
Post by: Arx on January 03, 2016, 01:46:24 pm
they do have those really strong kitchen appliance cleaning sprays nowadays in most supermarkets. They work wonders when you first wet the surfaces to be cleaned with hot water, let that soak a bit, then apply the spray.

Plus one to this. There are quite a few lye/lye-like oven cleaning sprays out there, which do magic on caked grease what with soap reactions and all.

If you can't find anything like that you can have a go with some bicarb, but I'm dubious about how well it'll work on a big problem.
Title: Re: Cleaning a really nasty old oven
Post by: Sappho on January 03, 2016, 02:12:10 pm
Thanks for all the suggestions. I used a *very* strong cleaner today and it didn't even come close to doing the job, but I've found a lot of people saying baking soda really works well, if you make a paste, spread it all over, leave it overnight, and clean it off with a bit of vinegar in the morning. So that's what I'm going to try next... Wish me luck! And I'm still open to other ideas, if you have them.
Title: Re: Cleaning a really nasty old oven
Post by: Purple Gorilla on January 03, 2016, 02:53:33 pm
Steel wool is already a good thing. Maybe first scrubbing it with dry steel wool, and then with wet one. Some time ago I used to buy damaged microwave ovens on Ebay, repair them and resell them. Steel wool worked well to clean, but you have to scrub very hard.

If you need lye, easy availible lyes are :
* Soda (Na2CO3) : availible as cleaning agent in drug stores (Schlecker ...). It is a lye, despite looking like neutral, because Natrium is very powerfull lye and carbonic acid a weak acid.
* Caustic Soda (NaOH) : Availible as Photo-developer at some chemists or photo labs.

Theese are probably bad choices, but for completeness :
* Pipe cleaner : A mix of Caustic Soda (NaOH), Saltpeter (KNO3) and Aluminium. When mixed with water it starts to boil and becomes higly caustic (both alcalic and oxidating). You may have to verify your age, to buy it, and you should wear protection googles while using it.
* Amonia (NH3) : Alcalic gas available disolved in water at some office shops for making blueprints (rare nowadays). Its is caustic to respiratory organs, so be carefull not to breath it in high concentrations.
* Potash (K2CO3) : A weak lye like soda. I don't know there to buy it, but you could make it yourself, if you have an open fire place or other sources of ash.
* Lime ( Ca(OH)2 or CaO) : Availible at the contruction shop (for mortar). Strong lye, thought you should wash it away before it sets. Here, you should also wear protections googles. And make sure, that you actually buy pure lime, and not mortar or cement.


If you can legally buy it, a very powerfully cleaning agent is also Hydrogenperoxid (H2O2). It easily dissolves rancid fat. Make sure, that you don't mix it with acid (vinegar), as a mix of oxidizers and acid is very corrosive to metal. Here in Germany, it is no longer availible, because of all the anti-terrorist laws, but I think in Czechia laws are more liberal with that things. You need a high concentration (~40%), so hair dye is not sufficient.
Title: Re: Cleaning a really nasty old oven
Post by: FallacyofUrist on January 03, 2016, 03:27:34 pm
Magic Eraser. Because that works wonders.
Title: Re: Cleaning a really nasty old oven
Post by: Sappho on January 03, 2016, 03:39:17 pm
Magic Eraser. Because that works wonders.

They don't exist here, I'm afraid.

Purple Gorilla, thanks for all the chemistry information. I'll give the baking soda thing a try, but if that still isn't enough, I'll definitely go through your list. I think available chemicals are very similar here and in Germany (I buy most of my cleaners at DM, apparently a German chain since all the labels on everything are auf Deutsch). So whatever is available there is probably here too, and you may be right that some laws may be less strict here.
Title: Re: Cleaning a really nasty old oven
Post by: wierd on January 03, 2016, 04:08:24 pm
Dawn used to make a "cold water soak" spray for removing gelatinized oils and greases from non-stick pans that you cant scrub. Let me see if I can find it.

Here it is


http://www.amazon.com/s/?ie=UTF8&keywords=dawn+power+dissolver&tag=googhydr-20&index=aps&hvadid=30903935781&hvpos=1t2&hvexid=&hvnetw=g&hvrand=3336898765213708831&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_1m0zo43cyb_b

It is a bit pricey, but it is non-corrosive, and does not have irritating fumes.  It's something you can literally spray on, wait a few hours, and wipe off without using gloves. 

Also, Magic eraser

http://www.amazon.com/Mr-Clean-Eraser-Cleaning-8-Count/dp/B001339ZMW/ref=sr_1_3?ie=UTF8&qid=1451855397&sr=8-3&keywords=magic+eraser

If you dont mind possibly poisoning yourself now, and also later from the residues vaporizing in the oven-- there's always MEK.

http://www.amazon.com/Klean-Strip-METHYL-ETHYL-KETONE-GL/dp/B000SKX7WK/ref=sr_1_2?ie=UTF8&qid=1451855487&sr=8-2&keywords=Methyl+ethyl+ketone

That stuff is low molecular weight, and liquefies gelatinized oils. It also is abosrbed through the skin, causes liver damage, damage to the central nervous system, and damage to reproductive health and the renal system. It is used in heavy industrial manufacturing as an industrial streangth degreaser prior to the application of very specialized coatings, like chemfilm. I would not really recommend it fo ruse anywhere near food prep.  Just mentioning it as the "THere's aways the 20 ton wrecking ball" type option.

I would try the cold water soak, and perhaps some food grade volatile oils, like wintergreen oil. Those are also able to liquefy stuck on greases and oils.


You know what, I have some stuck on gunk on the top of my stove, and some 100% purity volatile lemon grass oil.  I will test to see if it lifts the stuff off.

Edit:  Yes, the lemon grass oil is effective at removing the still "gelled oil" residues, but ineffective at removing carbonized deposits.  The magic eraser would do best on the latter.
Title: Re: Cleaning a really nasty old oven
Post by: i2amroy on January 04, 2016, 01:57:22 am
+1 to the steel wool pad suggestion (lots of times you can buy them in a pack of 3-4 for use in scrubbing dishes), though you might want to be a bit careful with it when you actually get down to the original glass/oven itself, since if you scrub really hard it will be possible to scratch it (though it still usually takes a fair bit of pressure to reach that point).
Title: Re: Cleaning a really nasty old oven
Post by: Sappho on January 04, 2016, 02:33:24 am
+1 to the steel wool pad suggestion (lots of times you can buy them in a pack of 3-4 for use in scrubbing dishes), though you might want to be a bit careful with it when you actually get down to the original glass/oven itself, since if you scrub really hard it will be possible to scratch it (though it still usually takes a fair bit of pressure to reach that point).

As I said in the first post, I've already tried steel wool and it didn't really do anything despite scrubbing with it for about 10 minutes with all the strength I could muster. I'm planning to try the baking soda thing tomorrow night, since Wednesday morning I'll have time to finish it before work.
Title: Re: Cleaning a really nasty old oven
Post by: kilakan on January 04, 2016, 03:06:29 am
There's a hot usage oven cleaner you can buy around here.  I use it on the woodstoves glass door.  Basically it's a spray to be sprayed on (you can also get a powder version) while the stove/woodstove is hot.  It works insanely well at taking a years build up of creosote off.  I think it's called easy off.  Not sure though, don't have any atm.

Anyhow, usually what you want to do for stove's and such is actually turn them on and then use a few layers of paper towel carefully to clean them.  Just wear an oven mit or be careful.
Title: Re: Cleaning a really nasty old oven
Post by: wierd on January 04, 2016, 09:01:56 am
easy off is sodium hydroxide in a soap suspension.  It tries to convert the long hydrocarbon chains in the oily gunk into a "soap", so that water can remove it.

It does not tackle carbonized deposits.

The lemongrass oil method I tested works better than easyoff, imho.
Title: Re: Cleaning a really nasty old oven
Post by: kilakan on January 04, 2016, 12:37:20 pm
Okay, it's not easy off I guess then.  But either way there is in fact a hot woodstove cleaner that works wonders on soot/ect
Title: Re: Cleaning a really nasty old oven
Post by: Purple Gorilla on January 04, 2016, 02:48:05 pm
I am pretty sure, that baking "soda" is in fact Natron (Natriumhydrogencarbonat, NaHCO3), which is not a lye as opposed to washing soda (Natriumcarbonat,Na2CO3), which is a lye.
Title: Re: Cleaning a really nasty old oven
Post by: Djohaal on January 04, 2016, 07:34:53 pm
If I remember my chemstry we have baking soda (NaHCO3 - sodium bicarbonate), sodium carbonate (Na2CO3) which is an even stronger alkali (~ 10,  bit more times more alkaline if the pKa values in wikipedia and my math are right), and caustic soda (NaOH, the base itself, not a salt) but the stronger bases are more difficult to find, and obviously more dangerous to handle; specially caustic soda, be very careful if you use that, can cause horrendous skin burns or even blindness if it hits your eye (unlike acid burns, base burns are actually worse because they keep on diffusing on the skin). What you want for cleaning caked grease stains is a very strong alkali to try and react with the fats and soften them. I may ask, is the oven easily deassembled? you might make some progress removing the parts and letting them soak overnight in hot or boiling water.

Natron is a mix of these two salts.
Title: Re: Cleaning a really nasty old oven
Post by: Sappho on January 05, 2016, 01:28:55 am
May I just say that I genuinely love that my cleaning question turned into a chemistry lesson. Only on Bay12!

My oven is definitely not easily disassembled. My plan is to do this: http://www.thekitchn.com/how-to-clean-an-oven-cleaning-lessons-from-the-kitchn-201191

I shall report back on how it went, hopefully tomorrow but we'll see. If it doesn't get it done, I will start trying some of you guys' more dwarfy suggestions.
Title: Re: Cleaning a really nasty old oven
Post by: Djohaal on January 05, 2016, 11:33:27 am
If all else fails bring it outside and use a pressure washer!  :P
Title: Re: Cleaning a really nasty old oven
Post by: Il Palazzo on January 06, 2016, 03:24:15 pm
And if that fails too, pick up a book or two from neoclassicist philosophers and redefine what it means to be a dirty oven.