Sciencemadness Discussion Board

what can i coat the inside of my homemade fumehood with?

EmmisonJ - 29-1-2009 at 07:00

i have a homebuilt fumehood that is particle board and screws holding it together. there will be acid vapors, flammable solvent fumes in this fumehood so i was wondering what i can coat the wood and metal with to protect them from corrosion?

should i put some type of rubber mat over the wood and spray some type of protective coating over the metal hinges/screws?

i'm not a handy person at all when it comes to building things so the easier the better

Ebao-lu - 29-1-2009 at 10:46

What is the material the boards are made of? If it is wood, then definitely you should protect, as H2SO4 fume or splashes will leave charred points that will tend to grow, besides wood is flammable.
You can try to protect the walls with aluminium foil, though it is not resistant to alkalines(but it is the easiest option).
For the bottom the best material should be usual tiles, but probably it is impossible to attach them directly to wood with cement, so use another layer made of the same tiles, attached with screws(carefully drill the tiles, screw head should not pass through the holes, unlike rest part of screw), with abrasive side looking "up". Then attach the second layer of tiles with cement or block glue(with glossy side "up", better to use water-resistant glue).

[Edited on 29-1-2009 by Ebao-lu]

EmmisonJ - 29-1-2009 at 11:03

the wood is particle board, like what is found in Office Depot furniture. :P

that would be a great solution and definitely something easy enough for someone unhandy like myself could pull off but a friend of mine will be performing an amalgam of aluminum in time.

do you think i could just get thin stainless steel sheets and use stainless steel screws or water-proof wood cement as you suggested, let everything be covered in stainless steel? if that is a good idea then is there a certain grade of stainless steel or some other better material i can put overtop the existing wood?

[Edited on 29-1-2009 by EmmisonJ]

jokull - 29-1-2009 at 11:35

I have used polyester resin to coat metallic structures for conducting HCl fumes. Indeed I designed a duct for a small galvanizing company. Polyester resin is cheap and easy to handle.

starman - 29-1-2009 at 16:30

Take it with a grain of salt as I have no practical experience - what about teflon based paint?

chemrox - 29-1-2009 at 19:27

I'd like to hear a little more about processing the polyester resin.. how to make a coating with it... what exactly to buy and how to mix it up, etc.

watson.fawkes - 29-1-2009 at 20:54

The easiest-to-acquire polyester resin is Bondo. Buy a can and slather it on. Use gloves. Not the very cheapest, though.

You can generally find polyesters at the same places you'd find epoxies for fiberglass and other composites work. In such a case, follow their directions.

Honestly, though, I think one of the cheapest coatings for a wooden-frame fume hood is another layer of wood. It's sacrificial, so plan on replacing it. Use whatever is dirt cheap, like 3/8" OSB. Hold it down with stainless steel screws, so you can unscrew it later with intact screw heads. Then mortar up the joints with Bondo (or suchlike) to avoid vapor penetration.

Magpie - 29-1-2009 at 21:24

Epoxy paint, although a bit expensive, is easy to apply and has excellent chemical resistance.

Ozone - 30-1-2009 at 19:32

I agree, Magpie. I found some epoxy spray paint that I used for the interior of my glove box. Works great! The two-part mix would be better, but the spray stuff is convenient and gets into the pores/irregularities of wooden construction with ease. All else is sealed with clear RTV silicone.

Cheers,

O3

EmmisonJ - 2-2-2009 at 08:15

thanks so much for the great ideas guys!

i've decided to use silicone on all the corners to make it airtight and epoxy paint over all the wood

watson.fawkes - 2-2-2009 at 10:25

Quote:
Originally posted by EmmisonJ
i've decided to use silicone on all the corners to make it airtight and epoxy paint over all the wood
I don't know your experience in construction, so please take this as a comment to newbies reading this thread (which may or may not include you). Paint first, seal second. Otherwise the paint won't adhere correctly next to the seals.

Eclectic - 2-2-2009 at 11:15

Or use automotive bondo to fillet the corners before painting thickly with epoxy.;)

EmmisonJ - 2-2-2009 at 13:47

Quote:
Originally posted by watson.fawkes
I don't know your experience in construction, so please take this as a comment to newbies reading this thread (which may or may not include you). Paint first, seal second. Otherwise the paint won't adhere correctly next to the seals.


my experience is close to none, thanks for adding that because i was actually going to do it the other way around

Panache - 2-2-2009 at 19:59

Line with cement sheet then thermally spray a seamless glass finish, lol. Or just go to your local glass shop and have them cut some pieces to size, then silicon (or 'chaulk' if USA) them in, which is almost as good as the thermal spray alternative. if you are wanting a benchtop surface also then get the shop to order a piece of borosilicate glass.
The glass shop will charge next to nothing for the sodaglass wall and ceiling panels and install will take like 10mins and you're done.

edit--get them to use 4 or 6mm non laminated glass for the walls and ceiling. The borosilicate sheet for the benchtop should be 6mm. For a small extra charge they will polish the edges for you, this will make the sheet easier to handle. When fixing them to the existing particle board simply run some silicon over the area and press the glass firmly on. Once the sheets are all in place silicon up the seams, or don't bother it likely will make little difference.

[Edited on 2-2-2009 by Panache]

Ozone - 3-2-2009 at 19:39

Sorry, I forgot to mention that the spray epoxy is a Plasti-Kote product. This stuff actually sticks (somehow) to silicone seals.

Cheers,

O3

Chainhit222 - 22-8-2009 at 12:14

I hate being a necromancer but I have some questions about chemical resistant coatings.

I have recently began working on my lab in a garage, and I made a rather large work table in the back (14 feet by 3 feet) out of concrete board painted with a "epoxy" paint by the behr company, claiming to be 1 part behr acrylic epoxy.

I wish it was more chemical resistant...
Granted, this crap was pretty cheap, but when I poured some 98% H2SO4 on it, it changed color to black, but I think it formed a "layer" of reacted whateverthehellitis and prevented the reaction from going down further, because when I wiped it off it was largely white. 70% HNO3 stained it yellow.

Would two part epoxies offer greater resistivity? Like those floor coating kits? Granted, its not too big of a problem because I do not plan on spilling a gallon of hot sulfuric acid on it, but it is worth looking into.

My fume hood working surface consists of a peice of some weird material that someone gave me, called it synthetic rock or something. Its pretty smooth, and very resistant, I spilled H2SO4 on it and nothing happened. It was resistant to acetone and HNO3 aswell. I was considering using a plane of glass for the work surface, but the synthetic rock works quite well.

zed - 27-8-2009 at 14:14

Chemically resistant materials. Start by using CDX plywood, rather than particle board. Particle board has poor resistance to that most ubiquitous of solvents...H2O.

As for chemically resistant liners.....Old stove panels might prove excellent. Just salvage an old kitchen stove or two. The side panels are typically steel, coated with a layer of white, baked on, vitreous enamel.

Such stoves can be found on Craig's list, free for the hauling away.

chemchemical - 18-9-2009 at 21:55

I have been thinking of a fume hood for awhile now and I personally would use a teflon or HDPE sheet as the bottom. They are very resistant and you would only need a thin sheet.

The walls I would use something less resistant since they won't encounter as many spills.

Jor - 18-9-2009 at 23:33

If using TEFLON, be very sure not too put hot objects (e.g. beakers) on it. TEFLON decomposes below 300C to very toxic products (HF, perfluoroisobutene, and other toxic products).

[Edited on 19-9-2009 by Jor]

JohnWW - 19-9-2009 at 00:46

What about flat galvanized iron for the walls, painted with a two-pot marine epoxy paint? I have seen thickly layered epoxy paints or varnishes used on wooden laboratory bench tops. Probably best of all for the walls would be stainless steel, but it is costly and difficult to cut to size without industrial-grade equipment.

MagicJigPipe - 19-9-2009 at 08:23

I too would use tile. Something else I've been thinking about... They make mirrored glass "tile" that can be glued to just about anything. I use it to protect my wooden desk from spills, splashes and scrapes. I must say that it works great and I see no reason why it wouldn't work for a fume hood. I'm not sure if you can cut them easily or not (like you can tile). Plus, it looks really cool and gives you all the benefits of having mirrors everywhere (being able to see things without moving stuff around).

Has anyone here ever seen what I am talking about?


[Edited on 9-19-2009 by MagicJigPipe]

chloric1 - 19-9-2009 at 16:14

No, could you possibly take a picture of these miracle tiles? I will probably construct a fume cupboard late this coming winter to be ready for the next warm season. The end of this years outdoor adventures is drawing near:(:(. I really need a house with a garage.