Sandblasting painted window frames?

[awbeattie381]

Hi All,

I am in the process of renovating my windows but because the previous owner decided to paint the window frames silver (as you do), its quite a slow process stripping the paint as well as scraping the old caulking tape and removing excess silicone!

I thought about getting the window frames sandblasted. Would this destroy the window frames or is it a delicate enough process that could work? I still intend on removing as much silicone and caulking tape as possible.

Thoughts?

[Mustang]

I would think "sand" may be too aggressive under the pressure required. I had my chassis blasted with Garnet (glass) it dosn't form in the crevises, but still may be too severe.
If you went to a powder coater, they have paint removing baths, it may be in your interest to get a quote for the whole job.

After using drills with every wizz bang brush known to man, every chemical gunk removing goop known to man....I came back to 3 x grades of steel wool (course/med/fine) then metal polish.

The results of the course moved the green & pitted gunk then the others polished the aluminium to a shine. You need to spray lanolin on the wool.
Before I used metal polish I diluted the lanolin from the metal.

Unless you pay, I can't see any other method than elbow grease, plain old petrol softens a lot of gunk.
We had 13 frames & it took months, one at a time, but I,m happy with the results.

[doublechevron]

If it's loose flakey paint, glass beads at a low pressure should get it off. It will also "texture" the alluminium too. The mastic will certainly be harder than the alluminium, so if you try to blast it off, you'll destroy the frame. I have built my own sandblaster unit .... You will use it LESS than you expected unless you have the time and money to do full restoration on cars/caravans. I posted some piccies of my setup over on the land rover forum.

www.aulro.com/afvb/2247272-post12.html

I wouldn't dream of going near windows with it .... countless hours of elbow grease is the only real answer. I worked out it was taking upto 5 hours per window to reseal on the caravan I'm doing.

20minutes to whip it out
1 hour to chisel the rock hard old mastic off
1 hour to carefully finish cleaning the mastic off with a small screwdriver and small stainless steel wire brush.
1/2 to tape of the window frame and wire brush it ....

and BLOODY SILICON... if anyone has pumped that nuts all over the thing ... add HOURS for careful removal

1/2hour to re-install.

seeya,
Shane L.

[tim]

I've stripped a bit of paint in my time. Assuming you have the frames out of the van, or aren't too concerned about the surrounding paint, I'd apply a thick layer of a methylene chloride based paint stripper, give it time to act, then scrape it off and repeat. If the surface is suitable you can extend the working time by putting a layer of glad wrap over the top. In moderate weather you can easily leave it 24 hours wrapped up, and pretty much all of the paint will lift off when you remove it.

I've found selleys silicone remover to be pretty effective, again you paste it on pretty thickly and wrap it in glad wrap and leave it. It will lift most of it off leaving almost no residue.

Tim

[awbeattie381]

So it sounds like elbow grease is the way to continue...I might double check whether the paint stripper I am using has methylene chloride. If it does, perhaps I need to use more of it and wrap with cling wrap. I dont need a finish like Mustang's amazing windows I really only want the paint gone! Might also have to check out the silicone remover if I find any bad areas.

Its a bit of a process though...we have only managed one window so far. Decided to break the van down into 'sides' so its less overwhelming.

Process has been:

Remove window
Disassemble
Buy new parts (if required)
Remove silicone (not that much actually)
Remove mastic
Strip paint
Paint winder boxes and cross shaft (assuming they are ok - it amazes me how a lot of them bend!)
Reassemble including new perspex
Reinstall with new mastic

Some windows will need new cross shafts, some new winder boxes and some new link boxes. All will need flyscreens, perspex to replace glass and glazing wedge and dust seals.

Its a bit of a logistical exercise and makes sense to do all windows at once (to save on postage for a lot of the replacement items) but I dont think I could manage the thought of that! haha

[tim]

A lot of paint strippers don't contain methylene chloride these days. It has been replaced with other stuff that is gentler on humans, but usually really slow on industrial or automotive types of paint. If it isn't burning your skin then it's probably not much good!

Tim

[Mustang]

Hi Andrew,
Don't forget to "congratulate yourself" when that first window is done.
Little chunks are better than un-achievable large ones.
I just kept looking at my first finished window & said s**t that looks good.

PS: respectively to Shane I can't get things done any where near his speed.

[jrabs]

Hi, I have use a cabinet type bead blaster on my frames with good results. As they had a fair bit of pitting from corrosion I wasn't to worried about a polished finish but it does give a uniform "grey" finish.
I have just left them that way.

[tedalley]

Andrew hi.
I removed all my windows and used wire brush to get all old silicon & paint of window frames.

Remember not to press down -- just let the brush do the work. You are the robot holding the drill -- NO DOWNWARD PRESURE.
I used 3 x brush wheels on all the windows and alloy edging around the van as well as anything that had any old silicon.

It takes longer but I didn't get any scratches on the alloy if anything the wheel buffed it up to a nice polish.

[awbeattie381]

Might pop into that big shed this weekend and buy a wire brush for the drill. I'll continue to use paint stripper as a first step but use the wire brush on those more stubborn areas. At the moment I am using 2-3 coats of paint stripper!

[Mustang]

Hi Andrew,
While you are there they have a look at the red synthetic wheel, which is a little less abrasive.
Its no good on Silly-cone but is good to flatten the surface after the wire wheel.