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Author: Subject: Cleaning hotplates... Potential solution
numos
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[*] posted on 12-10-2014 at 16:58
Cleaning hotplates... Potential solution


When I bought my hot plate from Ebay, it, like most used hotplates had a dark brown black stain on it. I was unable to clean it with solvents, and since it didn't affect the function I just left it.

Today while finishing up my phthalimide synthesis, some oil from the oil bath splashed on the plate and created another huge stain, this time forming a thick enamel whose thickness I could feel.

Here is the stain:
before.jpg - 200kB

I tried quite a few solvents, the result of water being here:
1.jpg - 154kB

After that nothing was removed, I'm guessing the surface was rough and the towel just "sanded" down the stain, and once smooth no additional progress is achieved.

Solution:
Piranha solution, place a few drops on the stain and let it sit for a minute, then dilute with water and wipe. (put on gloves for this step)
2.jpg - 129kB

After the second round of piranha solution:
after.jpg - 204kB




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Ozone
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[*] posted on 12-10-2014 at 17:08


I've found that spraying water on there while hot and wiping it off while boiling worked well.

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violet sin
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[*] posted on 12-10-2014 at 18:57


what about TSP or lye? I have always cleaned my pots and pans with either of those when nothing else worked. same with our utility sink, yard sale finds, tools after working on my truck, ice chests, etc. etc. etc. I thought this a helpful suggestion, because it is especially useful for cleaning a pan after frying up some tortilla's to make chips( oil + heat = polymerized crud ). you don't always get it first go, but it usually cleans up a LOT of it right off the top. just not if it is aluminum of course. but enameled surfaces yep.


edit spelling

[Edited on 13-10-2014 by violet sin]
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Praxichys
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[*] posted on 13-10-2014 at 04:16


Quote: Originally posted by violet sin  
what about TSP or lye?

Be careful with NaOH/KOH. I severely pitted the enameled top of my old Scholar PC-170 with a molten bath of NaOH. I can see NaOH solutions potentially concentrating on a hot surface.

Hydrogen peroxide applied while hot has worked well for me in the past, but these days I'll just let the plate run under the fume hood as hot as it can go for a little while. The stains remain but anything with thickness burns/fumes off.




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WGTR
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thumbup.gif posted on 13-10-2014 at 08:27


I use Piranha all the time for this very thing! Heating the hotplate slightly with the solution get things even cleaner. Just use ventilation (of course).
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[*] posted on 13-10-2014 at 12:16


How do you stop a cast iron top from corroding? Could I use high temp paint like for woodburning stoves?
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[*] posted on 13-10-2014 at 22:19


Praxichys : I don't heat it. maybe use warm water, but room temp is fine too.

but ya, in my experience, you can etch enamel if you heat it or leave too strong a solution on for too long. but to exfoliate the oil crud only takes a med strong solution at normal temps for 15-20 min. wipe rinse and repeat if need be. I use both often, but mainly TSP at work( not chem related ). prep kitchen and bathroom walls for drywall re-texturing jobs. the oil from soot and cooking are a PITA if you get lazy. always worth scrubbing for a few min, as opposed to having to do it again with free labor and material$ out of pocket.

to each their own, if others feel comfortable using piranha sol. that's fine. I'm good with something a bit more user friendly. my calloused hands don't mind a cleaning too bad if my gloves rip on the jobsite or home.

little_ghost-again ( LGA ): found this for you, hope it helps.

" Folks, a great cast iron paint primer is Seymor's Cast Blast (available in spray cans). It has a high particulate application property and has good rust prevention "
from this --> http://www.practicalmachinist.com/vb/general-archive/cast-ir...

and

http://astore.amazon.com/thewoodwhispe-20/detail/B0000DD1DV/...
suggestion from this thread here, http://www.thewoodwhisperer.com/articles/rust-prevention/
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