Film in mash tun

[Corey Smith]

   I am starting to get a thin yellowish film/buildup in the mash tun. Some of it comes off with high pressure hot water given enough time. I currently use a 140 degree PBW wash, then a warm citric acid wash. Neither is cutting through the film. When scraped off with my fingernail, the film holds together like a sheet. I am assuming it is proteins that have cross-linked? So far, have only had corn, rye and m-barley in there.

   Anyone have any insight/suggestions? Left a message with 5-Star to see what they say...

 

Corey

[Kindred Spirits]

Do you happen to have any pictures of the film? 

Is it all over the sides or just on the top?

[SlickFloss]

PBW is great for washing mild soil from sensitive metals [copper] but it's really not that great of a cleaner in general. If you're cleaning steel try caustic and citric recirculated through a spray ball. If your in WI Hydrite is a chemical supplier who can help you acquire those two chems, at least in my area. Spray balls and soaking aren't the same thing but sometimes that can work too but time time time time time. We use a trio of chems for really hard to clean kettles, think the yellow residue you're seeing as well as heavy water scale residue and protein residue that'll combine as like a super steroided out beer stone. For build up like that we use Grease X, D Scale, and Chelated Caustic pre acid rinse (name brand of chems from Hydrite). One thing to keep in mind is that scale and residue and coking put on at a specific temperature will usually not come off easily at temperatures below that point without a lot of heat chemical concentration and force (spray ball) or increased time for lower concentrations and or temperatures. If your cooking your corn to 170 or 190 or 200 or whatever, using a mild cleaner at a low temperature won't get that scale off unless it soaks for a very very very very long time. Try cleaning at or near the same temperatures you deposited the scale at and you should see it melt away.

Cheers, Welcome to WI, hope you enjoyed that white dog,

Slick

[Bourbonbeard]

We have a similar thing happen on our corn cooker every once in awhile. To me it just looks like a thin layer of cooked on grain stuck to the stainless. We run a CIP on our cooker and it cleans it right up. If it is what I think then just do a caustic cycle clean with oxidizer and then a rinse and sani cycle afterwards. Do your caustic cycle for a bit longer than normal. We use Lerapur 283 for caustic, Lerasept-O for the oxidizer, and Paracetic acid to sanitize

 

[PeteB]

" try caustic and citric recirculated through a spray ball." 

That reminds me that a new employee a few years ago thought it would probably be more efficient if he mixed the 2 together, should only take half the time. He told me he was going to study medicine. I am pleased that he changed his mind.

[Corey Smith]

Thank you for the advise, everyone.  I'll talk to Hydrite about a better(stronger) cleaning solution. Thanks for the referral Slick, they are close to us. Also, yes, thanks for the white dog sample. It was very good! I see that I did forget to mention that the mash tun does have a CIP.

The pic is of the man door. The film is mostly in a ring around the top, the door, and the mixing paddles, a little in a ring near the bottom, and nothing really on the bottom.

[Corey Smith]

Well, an hour wash at 205 degrees with PBW did it. Thank you everyone...

 

Corey

[Kindred Spirits]

Wow that a lot of washing, does it break up with brushing? It might be faster to try scrubbing it out, or spraying it out with a pressure washer.

[Corey Smith]

It did not scrub off. An hour with the CIP is pretty effortless, so I'm pretty happy with that...

[WMurack]

We've had this build-up on our mash tun before. Try a stronger PBW solution or another brand of Alkaline cleaner, I used Cir-q-late from Birko. We would soak at a very high temp and it would eventually come off.