Removing mill scale

[Davek0974]

Would anyone know what sort of media i would need to blast mill scale off of hot-rolled steel??

Its only small-scale parts, I have a 90l cabinet.


Thanks

dave

 

[mart]

At work (with an industrial size/type) shot blasting machine, lead shot was used for cleaning the scale from hot rolled stainless steel plate. Would the 901 have capacity to use something as heavy as lead shot? I see that the 901 uses alluminium oxide/glass beads (plus other media?)

 

[Davek0974]

Thanks

Its not 901 it's 90ltr Its a small cabinet, my parts are small.

Getting replies on other forums, it seems blasting scale is a waste of power and time, the best way to shift mill scale is a soak in either dilute Muriatic acid or neat white vinegar, the sort you get from supermarkets, about £1 per litre.

Apparently a 24hr soak in a plastic tray with lid will shift all the scale AND the plasma cutting dross in one go.

I'm going to try this tonight.

 

[overload]

Forget supermarkets, just get brick and mortar cleaner from wickes or similar, use it undilated and soak for only three hours roughly (I use alot of 6mm flats this way).

Wearing a pair of chemical resistant gloves, rub the mill scale off and place the part in water with bicarbonate of soda included for the same time period as the first. Dry straight away once it is removed from the water.

 

[mart]

Right ok. The Muriatic acid is one of the other names for Hydrochloric acid-(caution of cause). If the white vinegar works then you`re sorted. There is also the 2 litre bottles of value range cola that is acid-about 60p.Let us know how it works out. (I know that if I leave a teaspoon in the sink over night that I have used for red hot chilli sauce, the area that has been in contact with the sauce is like silver in the morning!)

 

[Davek0974]

The vinegar worked perfectly!

24 hrs and it shifted all the scale as well as the dross from plasma cutting.

Picking up a plastic tub this weekend and some more vinegaR too.

 

[SmartWerks]

Would citric acid not work? Would work out cheaper too i think?

 

[chunkolini]

I use citric acid a lot, if you mix it up with hot water it works in about half an hour on hot rolled strip. I keep meaning to buy one of those heater
elements used by home brewers. for long bars and strips I use a length of drainpipe with a bung up the end of it.it is also safe to dispose of down the drain as it is a food product.

 

[steviec_lj]

Chunko, save your money, get a cheapy fish tank heater from our Cheapanese friends on eBay.

 

[chunkolini]

I was not thinking of buying one, that is a dreadful word. But that sounds a beter idea.
I did some hot rolled 3mm sheet a couple of weeks back, it took about 15 minutes in hot water and the scale just washed off.

 

[dannyp]

forget builder merchant for brick cleaning acid ebay is your friend stronger and cheeper acid

 

[chunkolini]

Oi Stevie that's almost a fiver. Oh but free p+P from China.
I shall have to get one ordered.

 

[brewdexta]

I've got 2 or 3 gallon of 36% hydrochloric acid going FOC, collection only. I'm not going to use it any time soon and don't like it hanging around with young kids etc.

 

[SmartWerks]

forget builder merchant for brick cleaning acid ebay is your friend stronger and cheeper acid

forget builder merchant for brick cleaning acid ebay is your friend stronger and cheeper acid

contains methylene chloride or dichlorine methylene, not good stuff mate. Better alternatives in respect to health they just take a bit longer

 

[dannyp]

ACID allways lives outside the workshop in a barrel. i tend to tie things to a rope and dip them in there, then feed the rope through a hole in the lid and leave for a while.
if there is acid in the workshop things go rusty

 

[Davek0974]

I use citric acid a lot, if you mix it up with hot water it works in about half an hour on hot rolled strip. I keep meaning to buy one of those heater
elements used by home brewers. for long bars and strips I use a length of drainpipe with a bung up the end of it.it is also safe to dispose of down the drain as it is a food product.

What's a good source for citric acid?

I would not have any of the serious acids around due to pets and children etc but vinegar and similar are easier to manage.

 

[eSCHEn]

What's a good source for citric acid?

I would not have any of the serious acids around due to pets and children etc but vinegar and similar are easier to manage.

Big bags on eBay is where I get my supplies. Aquarium heaters are a good source of heat as well as the brewing specific ones can be a bit more expensive even though they're the same thing.

 

[chunkolini]

I get mine off fleabay 5kg bags cant remember the price which means they must be cheap.
I am always amazed when the scale comes off with a paint brush, the surface polishes up a treat with a bench grinder and wire brush. It leaves a nice texture to it.

 

[Davek0974]

Great, good price too.

Vinegar takes about 20-24 hrs to strip cold, would cold acetic acid be faster or similar ??

 

[SmartWerks]

I use citric acid a lot, if you mix it up with hot water it works in about half an hour on hot rolled strip. I keep meaning to buy one of those heater
elements used by home brewers. for long bars and strips I use a length of drainpipe with a bung up the end of it.it is also safe to dispose of down the drain as it is a food product.

It's not safe to put down the drain, the citric acid is but what is dissolved into it isn't. Your basically putting dissolved heavy metal deposits into the river.