F-18/F-8 vs. straight Lye and Oxalic?

Doing research on deck cleaning, I’ve noticed a lot of people use the PressureTek F-18 and F-8. From the MSD sheets I see the active ingredients are sodium hydroxide and oxalic acid, which are also mentioned a lot for this topic.

Why not just buy the straight chemicals and add a little of your own surfactant? What’s the advantage of using the name brand products?

Because I barely made it out of high school and was playing hooky during chemistry class. Bob Williamson and his crew of testers did all the math and testing needed.

So now, I just plug and play and go to work. Washing pays way more money than I could save trying to reinvent the wheel.


I get where you’re coming from. I’m not cheap; it’s more about what’s available locally at this point. I wanted to make sure that I’m not missing some key ingredient or reason for using the brand name stuff.

Bob and his company are awesome- I love ordering stuff from them. I just don’t feel like buying repackaged chemicals at double the cost (ok, maybe I am a little cheap :smirk: ).

If there are any chemically inclined people reading: does anyone know how the concentration of liquid NaHO (drain cleaner) compares with the dry crystals? For instance, would I need 2 pints of drain cleaner for every pound of dry lye?

Edit: on second thought, that’s probably a question better suited for Google than a power washing forum :slight_smile:


The act of not spending money is not to be confused with the art of making money.

You’re allowed to be cheap. And at least you are adult enough to admit it. :wink:


But it’s usually the ones that master both arts that get rich…

I hear you loud and clear, though :smile:

That would be very good information to know! Would you mind sharing it if you find out? I prefer using Bob’s stuff, but it would be helpful to have a back-up plan in case I run out or something. For example, I use Roof Snot as my roof cleaning surfactant, but, because a lot of guys use regular old liquid dish soap and have shared their “recipes”, I was able to use that instead when I had a couple of roofs to clean but ran out of RS because of not ordering soon enough.

Speaking of that (if I may briefly hijack), I did a little experiment the other day and found that 48 oz of Gain mixed with 80 oz of RS makes some of the thickest stuff you ever saw! Pours out of the container like a thinned out paste and, mixed 1 oz per gallon of roof mix, sticks like glue…hardly any runoff on a 12/12 pitch!!! (I’m gonna try 24 oz with 104 oz RS next week and see how that does)

Ok…back on topic. :grimacing:

So far it looks like my 2:1 figure was spot on. You want to find a drain cleaner with Sodium Hydroxide as the primary ingredient. Typical concentrations are between 35%-50% NaOH in water. I couldn’t find anything to indicate that it would ever be more than 50% in liquid form. So 2 pints for every pound of dry crystals is probably a safe place to start.

If you’ve been reading any of @Henry_Grover_Jr’s posts on WCR, his ‘transformer’ products are all about utilizing the base ingredients and tweaking them to the application. Most guys in PW’ing or even window cleaning don’t want to play mad scientist. But homebrew recipes have the potential for working better than anything sold commercially, as you can mix to suit and don’t need to worry about shelf life.

That’s a pretty cool discovery about the Gain roof mix. I’d love to see some video of that in action.

Do you guys care about your health --at all ?

Ignoring the troll, sodium hydroxide is just lye soap. Plain old potash. Just get a 50 pound bag of it in flake form and use as needed. My landa guy brings me 250 gallons of bleach every friday, restocks anything low in my parts bins and leaves a bag of potash if I’m low. I never have to call for anything unless its an oddball request. Make friends with your suppliers. I love Bob. We will be riding together in WVA in less than 24 hours but i order locally. I got my landa guy to get lemonator from bob so i now have a drum sitting in the shop all the time.


We’re doing a small roof job Monday. If circumstances allow, I’ll shoot some video. At the very least I’ll take some pictures of the “Slime” and post them for you.

Baller. I have no interest in ever going big time like you, but mad props for your success.

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It’s like giving a detonator to a 2 year old.

From what I have read Sodium Hydroxide & Potassium Hydroxide (potash) are very similar but there are some differences it seems. Potassium Hydroxide appears to be a better choice as related to this thread.