Best Clear Finish?

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Hi guys, I built these posts for a stepped retaining wall for my brothers house, it will have 2x8 treated lumber set in the slots.  Made these out of 2x3 rect tube, and 2.5" cold rolled flat, it's going to be clear coated so I wanted to keep everything clean as possible with out any mill scale.       My question is what do you guys think is the best clear finish to use on bare steel thats going to be out in the elements?     Of course powdercoat was my first choice, but powdercoat doesn't usually like surfaces that aren't blasted, and the coater would have to be very careful not to scratch or get any dust on it prior to coating.  I'm also thinking of just rcing it with a clear paint, but how long will that last?  Was wondering if there was anything else, like a polyurethane, or laquer? (don't know much about them)  Thanks for any input Attached Images
Reply:Hmmm, retaining wall and pressure treated lumber and plain steel?Not all together a good combination of factors there.The 'new' pressure treated lumber is -much- more corrosive that the 'old' CCA (arsenic) pressure treated lumber.  So much more corrosive that you can't put aluminum flashing in contact with it, and you are 'recommended' to use stainless or triple-dipped hot dipped galvanized or some of the 'rated' proprietary coatings in fasteners or hardware in contact with the pressure-treated lumber.Next, why do you want a clear coating?  You may be proud of the way you fabbed and welded the steel together, but why do you want a clear coating?To me, buried or ground contact steel and pressure treated lumber and wanting it to last for years and years says to make the steel last in that environment.  Which to me means hot dipped galvanized on the steel.  And -maybe- you can top coat that to get a different 'color' than just galvanized.  Or maybe some sort of 'industrial' or marine coating rated for ground contact or immersion (epoxy based?).Next, a retaining wall has to withstand a pretty good sized force of the dirt/rocks/sand/water behind it.  A bunch of 2x6 boards will NOT withstand that without bending and bulging, for 8 ft long boards trying to 'span' the full 8 ft between posts/supports.  Are you sure you have the wall sized and strong enough?  The boards and the posts and the supports and all?  A timber retaining wall make with 4x4 or 6x6 posts laid flat has to have a bunch of "dead men" laid into the structure in order to tie the wall into the hillside behind it.  Otherwise, the wall just bulges and/or breaks.  http://en.wikipedia.org/wiki/Retaining_wall  The best laid schemes ... Gang oft agley ...
Reply:It's going to be clear coated because that what my brother wanted to get that look, if I was to do it over again, I would have used stainless, but it's already done.  It's going to be more of a decorative feature than an actual weight bearing functioning retaining wall, I asure you it's plenty strong, I just called it a retaining wall because I didn't know how else to describe it.   Would it be a better idea to use pine or dug fir, then seal it so it won't be as corrosive as treated? Or even composite?
Reply:You don't mention any prep that you'd do prior to whatever coating,which has everything to do with the adhesion and life.Possibly:-wipe down with lacquer thinner, then sandblast,then wash with etchant (Ospho, etc. for phosphate etch and clean)then rinse/dry and coat.IMHO-a lot of clear finishes-are rather soft, not abrasion resistantcompared to those with pigment.Blackbird
Reply:Originally Posted by dave powelsonYou don't mention any prep that you'd do prior to whatever coating,which has everything to do with the adhesion and life.Possibly:-wipe down with lacquer thinner, then sandblast,then wash with etchant (Ospho, etc. for phosphate etch and clean)then rinse/dry and coat.IMHO-a lot of clear finishes-are rather soft, not abrasion resistantcompared to those with pigment.
Reply:In or on the ground, corrosion and rot and insects never stop.  The insects usually don't bother steel   , but LOTS of insect like to eat or dig/chew/tunnel through wood.Rot and mold and fungus bother wood, rot/corrosion/rust bother steel.If you want the wood parts to last, you have to use materials that resist insects and rot.  Pressure-treated wood rated for ground contact (not all is rated for ground contact, check the label and fine print!) can usually last OK.  Plain pine or doug-fir might be lucky to last 1-2 years in/on the ground.Is this 'thing' more of a landscape edging, with a 2x8 on edge as opposed to a "retaining wall" that is hold back a hillside of tons and tons of earth?  Not that it maters a whole lot from a materials standpoint.If the steel is pounded into the ground when you set the 'posts', then any coating -will- get damaged or destroyed.  If you dig post holes to set the posts and then -carefully- set the posts and backfill with fine-grained material (no big/sharp rocks) then -maybe- you could manage to not scratch the coating.  If you scratch the coating, then the steel will rust.  Well, barring maybe somewhere in the desert with no moisture in the ground at all.  A piece of steel might last for a while in that environment.  OK, you have plain mild steel and you want to keep and be able to see the heat-tint?  Tough call.  See what a local powder-coating company says about some clear powder coat on plain mild steel in the ground.  Polyurethane coating will degrade from sunlight UV over time, even the 'best' marine polyurethane coatings need to be redone periodically (thick spar-varnish with UV inhibiters included).  Same with a lacquer coating.A weathering steel (Cor-Ten or such) might have been a better material choice for a 'plain' steel in the ground.    http://en.wikipedia.org/wiki/Cor-ten  Hmmm, nope there.  One of the references from Mittal Steel indicates problems with Cor-Ten in ground contact applications as well as in contact with timber/wood.Or like you surmised, some stainless steel.  The best laid schemes ... Gang oft agley ...
Reply:Yes, will be set in pre-made holes, some sand, then some cement, no pounding thats, gotta be careful on the install.  Moonrise- I know that blacksmiths have a "wax" type mixture that they use when something is going to stay bare, I know that it darkens the steel, but thats ok.  Ever heard of anything like that? I've used boiled linseed oil before, works good, but needs to be re-applied every once in a while.  When I used to weld on thrush cropdusters, the factory would fill all of the fuselage tubing with linseed oil, what a mess it was!
Reply:Some blacksmiths use a wax, applied to hot steel, for INDOORS.Doesnt last more than a few months, outdoors.No clear coat lasts as long as pigmented paint.Clear powder coat is thick, glossy, and when it starts to go bad, its a really ugly problem- it starts to peel like a sunburn, but only in some spots. You cant touch it up, you have to pull everything out, send it out to be either baked, or sandblasted, or both, then repowdercoated.the best is probably a catalysed polyurethane, or some other fancy, expensive, 2 part paint, which is kinda like epoxy- you mix it up, spray it on, then hope you have enough time to clean out your spray gun before it goes off. They use stuff like this on commercial buildings, and on boats- often it costs a hundred bucks a gallon.There are a couple of clear coats used on sculpture- 2 different companies with similar names-Incralachttp://www.conservationresources.com...ction40_08.htm63 bucks a quart!Permalachttp://www.permalac.com/38 bucks a quart.a lot of sculptors I know use one or both of these. They usually need to be sprayed, and are fussy about prep, but work pretty well, as clearcoats go.
Reply:Thanks for the advice, I'll look into it
Reply:X2 on the Permalac...  That crap will last pretty much forever with about 3 or 4 coats.  Also, your 2-part Polymer (non-yellowing) type will put a 'WICKED' coating on that steel and you could EASILY 'set' those into the earth with no worries about rusting, cracking or peeling.  I accidentally dripped some off a cavitation plate I was repairing and that stuff is STILL on my driveway and that was 3 years ago!  You also won't have to worry about ANY issues with wood leech, due to it's 'impervious surface'.  For a nice thick coating, put it on with a 'Foam Brush' (foamie).  IF you DO decide to use this stuff, make sure you have a HEAT GUN!  It doesn't seem to matter how you 'MIX' the 2-parts together, you ALWAYS end up with bubbles, sometime thousands of them!  The heat gun on medium heat and low volume, will 'magically' pull the bubbbles to the surface and 'POP' them...  Works like a charm!Also, I have a similar type of retaining wall, all built with 2"x6" and 2"x10" boards supported only by 4"x 4" posts and they are holding back a 4 foot wall of earth and rock on 2 sides (10' long to the Face, 18' long, angled from 1' to 6') .  You DEFINITELY need some type of treated wood though...  Anything else is just a waste, although I'm pretty sure you already knew that.... :PCheers,Last edited by jman; 08-31-2010 at 02:51 AM.Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:Also, if you aren't planning on it, I would take the grinder and 'Flap-Disc' the entire surface (not the welds of course) using 40 to 80 grit (perference) and THEN Flame Paint the Metal with a torch!  You'll get some WICKED colors in the welded areas and the 'freshly ground' steel will give you some incredible patterns (especially with LOW grits, you get those nice swirly patterns.) and can draw color right into the areas if you like...  Also, food for thought....  Using 'SiLICON BRONZE' on a project like this would REALLY set it off and the 'Flame Painting' over the S.B. is 'Wicked Awesome'!... Seriously...Coat with the 2-part (non-yellowing) poly and you're good to go!Cheers,/Jman...Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:Can't be done, any clear coating whether polyuethane or powder paint the clear may holdout on the top of the posts and be creeping up under the clear from the bottom.You have to use zinc chromate containing primer or organic zinc based primer.I sandblasted and powder coated it and had it rust within two years visibly and painted sandblasted iron with "Endura" organic zinc then top coated with polyurethane and it looks the same.The only way you may get away with it is possibly mixing some zinc chromate in the clear to where the tint is barely visible and checking for corrosion.Change your choice of metals.
Reply:Originally Posted by pistolnoonChange your choice of metals.
Reply:LOL....   "Pistolnoon"   I do it ALL THE TIME!I have made stuff from COPPER, BRASS, MILD (lots), STAINLESS, and EVEN some PLASTICS and Mixed Media that is coated and that Hangs outside or 'Jammed' into the ground all Summer and all Winter.  Temperatures vary from 35 degrees celcius to -45 degrees celcius !  (You know what I'm talkin' about.... aren't you from Fort Mac??)  I've made belt buckles that are coated with POLY that I could throw into a bucket of water and it would stay that way FOREVER....Remember, the '2-Part' poly is the EXACT same thing as 'Casting Resin' and not 'The GLUE' type that everyone seems to 'connect' it with...  Ever seen those coins and bugs in those cubes of plastic?  How about those wood tabletops that seem to have a sheet of Ultra-Clear and Hard see-through suface?  Well this is EXACTLY the same stuff'!  Give ANYTHING a good coat, let it dry for a few days and then take a hammer to it,... You WILL bend or break the stuff UNDER the POLY before the actual Poly comes off...The ONLY thing that can cause it NOT to work, is if you dont' MIX the Stuff properly.  I use BIG-AZZ 'throw-away' syringes for EACH (resin AND hardener) and get an EXACT 50/50 mix.  The exothermic reaction begins and it immediately starts to thicken.  Don't Dawdle too long!  oh, and don't forget the Heat Gun... LOL.Cheers,Last edited by jman; 08-31-2010 at 02:58 PM.Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:jman, whats your source for that stuff?, what type of place sells it?
Reply:It's basically an 'Epoxy Casting Resin"  Some people i know have used the 'Fiberglass Resin' with a great deal of success, but I've never used that 'type' except in some type of autobody application (stranded).  I've always used the 'Poly' stuff.As far as price is concerned, I get it at COST+10% as my wife works at a 'Big Box' store, but you can pick it up at ANY Home Depot, Lowes, etc...  Just 'Stay Away' from the Craft Stores as they're about 5 times as expensive!  Basically, the larger amount you buy, the better the price, but I would suggest the 1-quart size kit (1 hardener, 1 resin in a kit) to see how you like it.  I think my last kit was about 15 bucks and the brand available to me at 'that time' was called 'Nu-Lustre-55' and that stuff cures FREAKIN' HARD!  If I'm not mistaken, they even have a more expensive 'UV-resistant' epoxy resin and that stuff is the 'BEST' that you will find.  BTW, there are TONS of them online.  I've used a 'number' of different resins and it seems to me that the 'Thicker' it is in the bottle, the harder and better your application is...Also, for anyone who like to fish, put a light coat on your 'expensive' cranks and rattle-traps and the paint will NEVER, EVER come off...  Not only that, but it hardens the platics (or wood) to the point that they become almost indestructible....  Awesome Stuff....Cheers,Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:...jeez you got all that nice warm weather in Calgary.... coat everything with polyurethane clear and let it go, not like its got wheels and going anywhere.Gotta admit I like that look myself.
Reply:Originally Posted by pistolnoon...jeez you got all that nice warm weather in Calgary.... coat everything with polyurethane clear and let it go, not like its got wheels and going anywhere.Gotta admit I like that look myself.