Window Painting

[davey7]

I know this isn't quite the forum, but since a lot of you are diy'ers I thought I'd ask it here.

I have steel windows which I need to paint and reglaze a few cracked panes. My question is, should I prime only before new glazing putty, or paint and prime and then, once putty cured (using specially formulated putty for steel windows) do another coat of paint?

I'm lazy and using spray paint after grinding the rust off.

Thoughts?

 

[danemodsandy]

You Need to Prime!

The frames will not hold glazing putty well until they are painted. An oil-based primer used to be recommended, but you want to check with a knowledgeable hardware-store person about what primer to use with the glazing compound you have in mind.

The freshly-puttied sashes then need to be primed before painting. It is a lot of work, but skimping on effort now just means early failure for the result.

One thing that will help you a lot - making a "rope" of putty by rolling it between your hands until soft and warm will make the glazing step go much easier. Roll a rope, press into place along one side of a pane, run the putty knife down it at a 45-degree (or slightly less) angle. Warm putty makes all the difference between a smooth, professional-looking bevel and a ragged, stubborn mess.

EDIT: You also need to use glazing putty meant specifically for steel sash. DAP makes one, and it's fairly easy to find.

 

[davey7]

Thanks - you've confirmed what I thought. I did some of the windows already with caulk rather than putty. I was in a hurry and they are fine, but going forward I will use putty (I have the steel sash kind already - apparently there is also a local brand which is even better). Should I prime only or paint as well?

 

[danemodsandy]

Davey:

That sash needs at least priming before you putty. Paint will bond to the sash very well, but putty won't bond to bare sash very well. But - since putty bonds to paint, that overcomes the problem of putty holding to the sash.

If you want an absolutely pluperfect job, you could prime and paint the sash first, then glaze and putty, then prime the putty and paint again.

If you're under thirty, you just might live long enough to get all of that done. ;-)

 

[sudsmaster]

Take notice of what kind of putty you use. Some kinds need to have an oil-based primer placed on top before painting with latex. And maybe even an oil-based paint instead of latex as well. A couple years ago I had a fun time scraping out all the painter's putty someone applied to the wood facade and doors to a 2-car garage. The latex based paint had failed over all the joints where the putty was applied. I then applied a 50-year caulk (DAP230) to the joints, covering up any residual putty, and primered over that with Zap 123 primer. Then a top coat of best quality latex semi (Behr Ultra). No sign of paint failure yet.

I'm in the process of re-roofing the carports here. The old fiberglass corrugated panels were disintegrating. Unfortunately someone - more than 30 years ago - had used painter's putty to try to seal them to the wall of an adjoinging building. I'm going to have to scrap all that off and figure out the best way to address the join. You can bet it won't involve painter's putty!

 

[davey7]

Luckily oil and lead based paints are still allowed on steel sash, for the moment, for exterior use only. Maybe I'll try one window primer and paint and another primer only. The windows I did already I painted fully then caulked (I know, I know, BAD) the missing putty and used caulk to reinstall a loose lite. So leaks so far... But putty will look nicer.

 

[fido]

I use car body polyester filler instead of putty these days, as it lasts longer and saves time. You do have to sand it so you have to be careful not to sand off any galvanising from the metal frame.

 

[danemodsandy]

Phil:

Have you ever had to remove any of the filler to re-glaze a window, and if so, how difficult or easy was that?

The reason I ask is that I grew up in a house that had steel-sash windows in its garage, which was underneath the house. Those windows had been glazed with cement in place of putty when the house was built (1949), because it was also "easier and lasts longer."

The problem was that when a pane broke, it literally took a cold chisel - driven by a hammer - to clean the old cement away for re-glazing. Whoever did the initial installation certainly found something long-lasting and convenient, but they also created a problem that lasted for decades.

So, it would be good to know how this product responds to removal efforts.

 

[davey7]

Yeah, the bondo would be too stiff and crack the glass. The putty can be heated with a special tool (which I don't) along the lines of a caulk cutter.

 

[hydralique]

It is important to remember that primer is porous, and is intended to provide the best possible grip on the substrate and in turn to provide a grippy surface for the paint. This is why steel or iron that has been primered but not painted will soon show rusty spots. I'd guess that the glazing putty will adhere to the primer better than topcoat paint, but if you get any water infiltration through the putty, such as happens when it gets older and cracks, the window frame will rust more quickly than if it had a full coat of paint before being glazed.

 

[fido]

Sandy, the filler is no harder than old putty, probably a bit softer. I don't think I have ever had to re-glaze a window done with it though and mainly I've used it for patching when some of the old putty has cracked and is falling off.

 

[davey7]

Thanks for the advice. The window is now primed. I'm debating painting the bottom of the "open" (where I took out cracked or broken glass) lites before I reglaze - the steel was rustier than I'd expected. Will try to post some pictures as I go.

 

[davey7]

So I finished the putty (thanks for the tips) but still can't get a "nice" crisp edge. When I get the pictures posted you'll see what I mean. However, the windows no longer leak around the glass and with all the chipping paint gone, shut tightly.

 

[davey7]

Here are some before pics.

 

[davey7]

And an after...

 

[davey7]

Yet I still can't get a smooth putty bead - partially it's hard on this window since I can't really reach well.

 

[davey7]

Last one... They still need to be painted of course. This one has sort of a "pocked" finish, need to improve my technique.

 

[westie2]

Here is the tool you need. I have had mine for 35 years or more. One thing to help with the pitting is to have the glazing putty worked very good and soft. Also have a small rag with regular cooking oil on it not much and keep the V blade and the Flat edge clean with the oiled rag. Works great. Take the glazing putty work it like clay dough then roll it out into a long enough strip to cover the one section and finger press it in the use the flat edge to press it down good the to the V side to run it down the whole section.

http://www.wgsonline.com/glass/210-40460.html

 

[sudsmaster]

If I encounter badly rusted steel around the property that needs to be painted, I'll first scrape off as much rust as possible, and then treat it with Jasco Primer/etcher. This is a phosphoric acid chromate liquid that turns the rust into a non-rustable black iron phosphate compound. Then after 24 hours (or sooner, depending) I'll give it a good prime with a rusty metal primer (usually red or brown in color), let that dry overnight, and then paint with oil or latex (oil is usually best for metal, seals out moisture better).

For galvanized I've been using Zinsser Bullseye 123 water based primer. Oil based primers and galvanized metal do not mix well. The zinc in the galvanizing will turn the oil in the primer into a soap (saponification) causing it to peel or flake off. Same with oil paint directly onto galvanized metal. In some cases a vinegar wash will prep the galvanized metal for paint, but I'd still use a good latex if direct on the metal.

The roof on my garage is corrugated galvanized steel. It's a high quality product - thicker and better plated than the crap that Home Depot sells. But someone once pointed it with an oil based aluminum paint, long ago. Well, that paint was flaking off when I bought the house 15 years ago, and it's all flaked off now. I'll probably wash it down with a mild soap solution, rinse with vinegar, prime with Zinsser Bullseye 123, and the give it a nice coat of white latex paint. This may keep the garage cooler in the summer, and it will match the white corrugated polycarbonate panels I'm installing on the attached carport roof.

[this post was last edited: 10/18/2013-20:43]