farmer brown said:
Hey All
I've been reading about cleaning plastic firkins (from brewery plastics) and was just wondering if anybody can share there cleaning/sterilising techniques. I understand caustic soda is best for the first primary clean but I have read all kinds on dosage and soaking times. Also, is caustic soda ok to use on plastic kegs?
I've just picked up my first batch of firkins from my local and they are pretty smelly!
Here is my plan.
1) Mix a ratio of 30g/Liter of caustic soda and add 2 liters of the solution to each firkin.
2) Give the firkin a good shake every 10 minutes for an hour or two and leave it overnight, next morning give it a good shake and then wash out a couple of times with 5-10 liters fresh water.
3) When ready, sterilise with starsan for 10 minutes before filling
Any advice much appreciated :thumb:
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Should warn that caustic is an irritant so always wear gloves and if you are splashing it around with it the eye protection as well. If it comes in contact with skin or eyes rinse out immediately as per manufacturers recommendations.
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All depends
Probably, your firkins are made out of hdpe plastic, like most homebrew fermentation vessels, but maybe they are not. All depends on the material they are made of and manufactures recommendations. If the caustic is made for brewing it will probably say on pack what materials they can be used on.
Specifically, the caustic is measured in parts per million. When using caustic to clean stainless steel we used to use 500ml per 20 l HOT water (~60C). however the caustic was itself a caustic product. The active caustic was 5% (I think) giving something like 300ppm (I think, too late to do proper maths now :hmm:) However, the precise measurements will vary from manufacturer because they will all use different concentrations. As for the contact time, it seems very long to leave it overnight. The effects of agitation would be minimal I think. Caustic was described to me by a brewer as liquid sandpaper. The heat of the solution should get the effect.
Should have said make sure to rinse clean everything first, clean to the naked eye. If applicable make sure there is no CO2 trapped in the vessel as it neutralises caustic somewhat. A property of alot of caustic solutions is that it darkens on contact with organic matter ( maybe organic matter in general or a certain type in particular, not sure) this can give a visble clue to whether hidden interiors are clean. One hour should be more than enough but I would chance half that. You should be able to observe visually.
Next, again make sure to rinse with hot water. A 1:1 or possibly 2:1 rinse to clean ratio might be necessary. The water will have a soapy feel if any caustic remains.
After the rinse, sterilise as you said. Certain sterilisers pair well with each other. Caustic cleaner and peracetic acid sterilisers are common combinations in food industry.
As for starsan, it comes so highly recommended by home brewers. If you were to use it maybe try pbw cleaner with it instead. It is not caustic soda but I do believe is caustic based. Made by the company that makes starsan and doesn't require the higher temperatures. That temperature alone can cause some plastics to expand and take in cleaning compounds which ordinarily will never rinse out, yet some how contaminate your beer.
Alternatively, a good dose of vwp and warm water should clean and sanitise. Just remember to rinse thoroughly afterwards idealy with warm water.
Hope that information was helpful.
