Looking for an Acid Resistant Paint

[Matt “Ducky”]

I have had a heckuva time looking for and trying to find an acid-resistant paint for plywood for my fume hood that I am building that is resistant to more, especially aqua regia.

Acrylic will not work because it is very susceptible to breaking down in aqua regia.

Epoxy seems to be the best bet, but if anybody knows the exact kind of paint in particular, that would be great. I need a gallon of it; I’m having difficulty finding it. If anybody has any ideas, please let me know.

 

[andu]

Upon a quick google I found this thread. https://goldrefiningforum.com/threads/need-help-on-leds.14468/
AR seems to dissolve most epoxy resins. I do wonder of such paint myself.

I had to google acid resistant paint to find quite a few results.

 

[Matt “Ducky”]

Upon a quick google I found this thread. https://goldrefiningforum.com/threads/need-help-on-leds.14468/
AR seems to dissolve most epoxy resins. I do wonder of such paint myself.

I had to google acid resistant paint to find quite a few results.

 

[kurtak]

IMO you can forget the idea of using painted plywood for building your fume hood

Painted plywood just will not hold up - the corrosive chemicals we work with are going to get under the paint & cause the paint to peel away from the plywood --- just like the chems we use to recover gold foils from gold plated fingers/pins get under gold plating to relieve gold plating from base metal those chems get under paint & cause the paint to start peeling

Depending on how much chem work you do in your hood the fumes from reactions will cause the paint to start peeling from the walls & ceiling of the fume hood within a year or two - spills on the floor of the hood will cause the paint to start peeling in even less time - like plus/minus 6 months

And for what it is worth - any reactions with nitric acid will cause the wood fibers in the plywood to turn in to "gun cotton" once the paint starts peeling - gun cotton is VERY flammable meaning your hood is going to become a fire hazard in your lab once the paint starts peeling &/or nitric spills get under the paint on the floor of the hood

Use the plywood you bought to build something else - then go to the lumber yard & buy melamine to build your fume hood out of

Melamine is incredibly hard & very acid resistant - it is also very smooth & so is very easy for wiping up spills

In this thread you will see pics of the fume hood I built out of melamine

https://goldrefiningforum.com/threads/building-a-chemical-fume-hood-with-a-plain-steel-blower.23107/

I used that hood everyday for 10 years & other then stains on the floor of the hood from spills the hood was as good as the day I built it

To put that in perspective for 10 years my hood ran 24 hours a day 7 days a week - the one & ONLY time I shut that hood down was for a couple days to up grade the venting system with bigger vent pipe & bigger blower

Go buy melamine to build your hood - use the plywood you bought to build something else

Melamine will last MUCH longer & your hood wont become a fire hazard like painted plywood will

Here is a like to melamine at Home Depot - make sure to get the double sided melamine & not the single sided melamine

https://www.homedepot.com/p/Melamin...ickid=VpVXxXSk1xyPTmowC70DE3uXUkHRA5XIr1bTSc0

Kurt

 

[Dreamer]

Kurts recommendations is what I did. Turned out really well and very resilient. The only thing I could add is to make the floor out of a PTFE sheet and run a small side and back splash out of it. Spills happen and the floor of the hood takes the brunt. It's a bit pricey but the best I've found for Sulfuric, Nitric and Hydrochloric resistance. Pick up a can of Liquid Plastic and spray a light coat on any metal along your fume path and anticipate pooling of acidic condensation. It will save you a lot of time and money in the long run.

Hope this helps. I wasted many weeks and a lot of cash dealing with poor forethought. Hope you can avoid it.

 

[eaglekeeper]

Exactly as Kurtak mentioned...

I got something similar to this and just cut it down to fit my work space. The one I bought was a little deeper, but this was the best picture I could find. Aside from some staining it has held up since 2019.....If you leave sulfuric acid on it for too long, then yes I will deteriorate at that spot.

https://www.lowes.com/pd/allen-roth-allen-roth-3-Shelf-Bookcase-White/5001233105

Looking back....It would probably be easier to just buy the individual panels. Trying to find the exact size of bookcase I needed was a pain. Also, drilling pilot holes for the fasteners is important because this stuff likes to split real easy.

 

[anachronism]

PTFE seems pretty good all round but it has one Achilles heel. AuCN eats it hehe.

Edit for typo.

 

[Matt “Ducky”]

IMO you can forget the idea of using painted plywood for building your fume hood

Painted plywood just will not hold up - the corrosive chemicals we work with are going to get under the paint & cause the paint to peel away from the plywood --- just like the chems we use to recover gold foils from gold plated fingers/pins get under gold plating to relieve gold plating from base metal those chems get under paint & cause the paint to start peeling

Depending on how much chem work you do in your hood the fumes from reactions will cause the paint to start peeling from the walls & ceiling of the fume hood within a year or two - spills on the floor of the hood will cause the paint to start peeling in even less time - like plus/minus 6 months

And for what it is worth - any reactions with nitric acid will cause the wood fibers in the plywood to turn in to "gun cotton" once the paint starts peeling - gun cotton is VERY flammable meaning your hood is going to become a fire hazard in your lab once the paint starts peeling &/or nitric spills get under the paint on the floor of the hood

Use the plywood you bought to build something else - then go to the lumber yard & buy melamine to build your fume hood out of

Melamine is incredibly hard & very acid resistant - it is also very smooth & so is very easy for wiping up spills

In this thread you will see pics of the fume hood I built out of melamine

https://goldrefiningforum.com/threads/building-a-chemical-fume-hood-with-a-plain-steel-blower.23107/

I used that hood everyday for 10 years & other then stains on the floor of the hood from spills the hood was as good as the day I built it

To put that in perspective for 10 years my hood ran 24 hours a day 7 days a week - the one & ONLY time I shut that hood down was for a couple days to up grade the venting system with bigger vent pipe & bigger blower

Go buy melamine to build your hood - use the plywood you bought to build something else

Melamine will last MUCH longer & your hood wont become a fire hazard like painted plywood will

Here is a like to melamine at Home Depot - make sure to get the double sided melamine & not the single sided melamine

https://www.homedepot.com/p/Melamin...ickid=VpVXxXSk1xyPTmowC70DE3uXUkHRA5XIr1bTSc0

Kurt

Thank you very much, Kurt. I have some melamine already, so I will take your advice and use the melamine. Im glad I read this when I did. Thank you.

I assume you had no issues with the melamine due to its hygroscopic nature? I live in East Texas, and humidity can be an issue for melamine unless a sealant is used.

 

[kurtak]

I assume you had no issues with the melamine due to its hygroscopic nature? I live in East Texas, and humidity can be an issue for melamine unless a sealant is used.

When I had my lab set up & was full time refining I was living in Wisconsin where the humidity is often also high like 90 - 95% humidity & had no problems

Most melamine is made with particle board & yes particle board in & of it's self without a protective coating is susceptible to soaking up water from the air so the only place there may be an issue is at the edges where the sheets are not coated with melamine - so you may see some swelling at the edges

As I said - my hood ran 24/7 with reactions happening everyday so LOTS of steam created from evaporation from beakers on the hot plate everyday all day --- the only place I had a problem with the melamine swelling up was at the raw edge of the hole where the 6 inch vent pipe in the ceiling of the hood was & that is because I simply screwed the flange for the vent pipe to the top of my hood leaving that edge exposed to all that steam--- so when I cut a new hole to up grade to a 10 inch vent I cut the hole big enough to slip the flange up through the hole & glued it in place with contact cement & used plastic bolts nuts & washers to bolt the flange in place & as well ran a bead of silicon around the gap between the vent flange & the hole edge where the flange came through the top of the hood & had no issues for the 8 years I ran the hood with the 10 inch vent pipe

Also - if your vent pipe runs horizontal (like mine did) make sure that vent pipe runs "a bit" down hill "away" from the hood & not level &/or down hill towards the hood --- otherwise condensation that builds up in the vent will run back down to the hood & drip back into the hood

Other then the issue of the raw edge of that first 6 inch hole I had no issues with my melamine hood even though steam was being generated in the hood from reactions everyday

Just be sure that your vent pipe & blower are big enough to keep not only fume but as well the steam evacuated from the hood

Kurt

 

[4metals]

Look up Novolac epoxy coatings, they sell an epoxy that offers the best option for nitric exposure.

We are away eclipse watching and my forum app won’t allow me to post a link.

 

[Matt “Ducky”]

When I had my lab set up & was full-time refining, I was living in Wisconsin, where the humidity is often also high, like 90 - 95% humidity & had no problems

Most melamine is made with particle board & yes, particle board in & of itself without a protective coating is susceptible to soaking up water from the air, so the only place there may be an issue is at the edges where the sheets are not coated with melamine - so you may see some swelling at the edges

As I said - my hood ran 24/7 with reactions happening everyday so LOTS of steam was created from evaporation from beakers on the hot plate everyday all day --- the only place I had a problem with the melamine swelling up was at the raw edge of the hole where the 6-inch vent pipe in the ceiling of the hood was & that is because I screwed the flange for the vent pipe to the top of my hood leaving that edge exposed to all that steam--- so when I cut a new hole to upgrade to a 10-inch vent I cut the hole big enough to slip the flange up through the hole & glued it in place with contact cement & used plastic bolts nuts & washers to bolt the flange in place & as well ran a bead of silicon around the gap between the vent flange & the hole edge where the flange came through the top of the hood & had no issues for the eight years I ran the hood with the 10-inch vent pipe

Also - if your vent pipe runs horizontally (like mine did), make sure that vent pipe runs "a bit" hill "away" from the hood & not level &/or downhill towards the hood --- otherwise, condensation that builds up in the vent will run back down to the hood & drip back into the hood

Other than the issue of the raw edge of that first 6-inch hole, I had no problems with my melamine hood even though steam was being generated in the hood from reactions every day

Just be sure that your vent pipe & blower are big enough to keep not only fume but as well as the steam evacuated from the hood

Kurt
Thank you very much for that info. I have been researching this for quite some time, and I’m always hoping for new information. From what I have read about the vent piping, it must have a 90° angle, not left more than 3 feet after it leaves. I plan to vent it away from the vent hood, obviously, and then up the side of the building outside of the shop, and then I run the numbers. It should be able to be the exhaust fan should be able to move just a few traps, at least so that it doesn’t flow back. I may be considering putting in a second for a boost.

If you’re OK with it, I would love to consult you further on this if you don’t mind. I could send you my design on what I’m wanting to do it’s pretty basic I think it is there’s a lot to it. Thank you again

 

[Lou]

PTFE seems pretty good all round but it has one Achilles heel. AuCN eats it hehe.

Edit for typo.

I've seen that before but I think it's an easter egg, Jon. Now molten alkali metals are another story. That's what they use before gluing them up.

As Matt found, Novolac-class epoxies hold up well against aqua regia. We use those or vinyl esters for containment floors at work. They still require clean up.

Your best bet is melamine as Kurt has noted.
As for the edges...paraffin wax them. Now they're water and acid proof. Only a few acids will eat paraffin wax and if you're working with those (not much of anything but PTFE) will stop them.

 

[eaglekeeper]

Lowes does sell these panels with melamine on three sides. As long as you plan your cuts well, you can limit your exposed edges. Unfortunately they only have a couple of different sizes, so the size of your work space might be an issue. Also I forgot to mention, counter sinking the screw holes so you can seal them over. But as we all know, Hydrochloric fumes will eventually find its way under the sealant....just give it time.

https://www.lowes.com/pd/Rubbermaid...L-x-11-8-in-D-1-Decorative-Shelves/5014178175

I live 5 miles from the Gulf here in Florida and I've had no issues with humidity. Splitting was my biggest problem during assembly....just select the right size for a pilot hole and don't over tighten the screws.

 

[kurtak]

We are away eclipse watching and my forum app won’t allow me to post a link.

So your going to "watch" the world come to an end tomorrow (according to some of the conspiracy theory's I have seen)

Me - I am on the other side of the country so I don't get to "watch" the end - just get to wait for it to end

Kurt

 

[Dreamer]

You can get iron-on melamine edge banding for your exposed cut edges. Rub the joints with parrafin like Lou suggested. It worked for me, and trust me, I've had plenty of accidents to put it to the test.

 

[4metals]

Me - I am on the other side of the country so I don't get to "watch" the end - just get to wait for it to end

Well it didn’t end 7 years ago in Charleston S.C. When we went there to see it so this time I am confident it won’t end this time either!

But we have no shortage of armchair scientists who say the end is possible and the total solar eclipse proves it…….. and then on Thursday before the big event we have a “major” earthquake in the East.

Surely the Aqua Regia Gods are clamoring. Test all of your solutions and prepare for the worst!

 

[Master Nater]

has anyone else tried the world of rubber coating? i'm just a newbie, but has been great to clean up off of, provides great traction, and as far as i can tell, as turned my entire fume hood into secondary containment.

 

[anachronism]

So your going to "watch" the world come to an end tomorrow (according to some of the conspiracy theory's I have seen)

Me - I am on the other side of the country so I don't get to "watch" the end - just get to wait for it to end

Kurt

Yeah! Strangely we apparently have a partial view of it where I live in the UK

 

[Yggdrasil]

So your going to "watch" the world come to an end tomorrow (according to some of the conspiracy theory's I have seen)

Me - I am on the other side of the country so I don't get to "watch" the end - just get to wait for it to end

Kurt

Well there has always been a bunch of people seeing the end of the world through the times,
in the old days they were standing/walking around the squares trying to ignite some interest and was easy to avoid.
Today they have these viral tools like Social Media provides and can at times require some effort to avoid.
Talking to them has never worked.

 

[Darkthirty]

Well there has always been a bunch of people seeing the end of the world through the times,
in the old days they were standing/walking around the squares trying to ignite some interest and was easy to avoid.
Today they have these viral tools like Social Media provides and can at times require some effort to avoid.
Talking to them has never worked.

Everybody gets their own end of the world eventually...