Clear coat steel

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Author Message J. Peter Jordan Senior Member Username: jpjordan Post Number: 769 Registered: 05-2004 Posted on Thursday, September 18, 2014 - 04:21 pm:    I have a designer who wants to apply a clear coating to interior structural steel, starting with a shop-applied clear coat. Has anyone seen this done successfully? Dave Metzger Senior Member Username: davemetzger Post Number: 536 Registered: 07-2001 Posted on Thursday, September 18, 2014 - 05:16 pm:    I've done this for interior ornamental metal glazing framing, using small angles and flats, but not for structural steel. I've be leery of a shop-applied clear coat, especially if there will be field welding. Will need research--VOC-compliant clear coatings for steel are not thick on the ground. Ronald J. Ray, RA, CCS, CCCA Senior Member Username: rjray Post Number: 130 Registered: 04-2004 Posted on Thursday, September 18, 2014 - 05:43 pm:    Contact your nearest Tnemec rep. Consider SSPC SP6 or higher for surface prep. The Tnemec rep should know if a different surface prep is required. Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC Senior Member Username: redseca2 Post Number: 456 Registered: 12-2006 Posted on Thursday, September 18, 2014 - 06:18 pm:    I would really want to know what the designer expects as a final work result. If they want something perfectly uniform I would instead really look at Shop Prime Coats followed by high quality (Tnemec or equal.) field base coats, followed by a topcoat that "looks" like (whatever they think) raw steel looks like. That is a bid-able work result. Satisfying a designer's mental image through increasingly rigorous SSPC preparation techniques can be a long unhappy road. You would need to do some careful mock-ups. Do they also want entire AESS option set applied as well? J. Peter Jordan Senior Member Username: jpjordan Post Number: 770 Registered: 05-2004 Posted on Thursday, September 18, 2014 - 07:10 pm:    I have already contacted Tnemec as well as S-W and PPG. This is not AESS, but they want the look of "bare steel." I have tried to explain that the look of bare steel is rusty mill scale, but that is not what they want. ken hercenberg Senior Member Username: khercenberg Post Number: 823 Registered: 12-2006 Posted on Thursday, September 18, 2014 - 07:33 pm:    Had designers who wanted bare steel with clear coating at a monumental stair. Tried to talk them out of it. Used Tnemec's clear urethane topcoat over prepared steel (SP-6). Owner saw it and made us pay to blast it and paint it. Lisa Goodwin Robbins, RA, CCS, LEED ap Senior Member Username: lgoodrob Post Number: 253 Registered: 08-2004 Posted on Friday, September 19, 2014 - 10:14 am:    Clear coating, blackened, and blued steel are very trendy again. You can trace this to a 2007 KieranTimberlake study on blackened steel. Usually this idea goes away during design. However, I do have at least two client Architecture firms who have been successful with the clear coating, especially for interior HM doors and frames and interior railings. It's appropriate for sort of industrial chic designs, like renovated mill buildings. You'll want preconstruction meetings, coordination with the manufacturer, and lots of samples. I'm sharing the following information because it took a long time to figure it out. We've only done it for private work so far, but it's been up since 1999, without complaints. You need to specify completely unprimed steel. For doors and frames, it looks something like this: Hot-Rolled Steel Sheet: ASTM A 1011, Commercial Steel (CS), Type B; free of scale, pitting, or surface defects; pickled and oiled. For factory fabrication, components must be TIG welded, not MIG welded. Do not dress welds smooth and do not prime. de la Fontaine (Canada) has made door and frame products for this purpose. The clear coat finish is field applied per Section 099000 Painting and Coating. My spec looks like this: Interior Metals (Doors, Frames, Stairs, Railings, and Metal Fabrications), Clear Coat Finish: a. Preparation: 1) Sand blast paint and prime coats, if metal did not arrive uncoated. 2) Solvent Clean SSPC SP-1 b. Two Coats: Clear Solvent-Based Acrylic. One contractor has been using Azko Nobel; Flood Penetrol. It looks good; the Owner is happy; and that's what I know. - J. Peter Jordan Senior Member Username: jpjordan Post Number: 771 Registered: 05-2004 Posted on Friday, September 19, 2014 - 10:50 am:    Lisa, do you have any idea if this would work on structural steel sections (seems like it should, but one never knows). Dave Metzger Senior Member Username: davemetzger Post Number: 537 Registered: 07-2001 Posted on Friday, September 19, 2014 - 10:51 am:    In looking up this product, the solvent is petroleum distillate, with a VOC listed as "Does not exceed 550 g/L." Lisa, have there been any issues about field applying this product due to its VOC content? Lisa Goodwin Robbins, RA, CCS, LEED ap Senior Member Username: lgoodrob Post Number: 254 Registered: 08-2004 Posted on Friday, September 19, 2014 - 11:15 am:    Peter, I don't know about structural steel. I don't see why not, but it may be harder in practice. Dave, I've asked that question too. I think AFM Safecoat Acrylaq would be a more environmental option. I've been asking Architects to send me approved submittals for this and other oddball painting products. I was surprised by this one. - Ed Storer Senior Member Username: ed_storer Post Number: 10 Registered: 05-2009 Posted on Friday, September 19, 2014 - 12:06 pm:    I've been specifying Permalac EF by Peacock Laboratories. Haven't had much feedback, so i guess it works OK. Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 1381 Registered: 07-2002 Posted on Monday, September 22, 2014 - 03:03 pm:    I've worked with a variety of clear finishes for steel, and in many cases the product manufacturer will not warrant the application because they cannot control the prospect of any residual moisture on the steel -- which then bubbles up the surface and clouds the finish.