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Old 28-11-2012, 19:39   #16
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

NahanniV
Did you use gloss or flat Krylon Fusion paint? Did you sand or clean the acrylic before spray painting ?
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Old 28-11-2012, 20:01   #17
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

I used gloss.

I gently cut the paper backing on the acrylic with an exacto knife so that about 1/8" would be visible from inside. Removed the strip around the edge and painted (spray paint) imediatly. Was careful not to touch the acrylic after removing the masking.

I did not do any further cleaning of the painted acrylic before installing, but tried not to touch it.

The cabin top was scraped, scrubbed and wet sanded to remove all the old silicone sealant that had been applied over the years.

When I tested the adhesion of the 795 I did not clean the acrylic either. It never peeled away from the surface, the surfaces were always still coated with silicone even after the joint was broken.
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Old 28-11-2012, 21:28   #18
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

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Originally Posted by Ian R View Post
I tried using tape but had better results with 795 and small pieces of tape used to space and hold window in place until 795 sets. 795 fills any bumps , tape will pull the acrylic to the shape of the bump.
Butyl tape and 795 is a great combo. You can use less of each. Actually much easier to kepp clean because the butyl tape comes in rolls with one side attached to waxed tearable paper.

Here's how I do it:

Use a box cutter on a cutting board to cut the butyl tape without stretching it. Run a continuous stretch of the butyl tape around the out side edge of the part to be bedded. Lay it flat and do not overlap. In other words frame the out side edge of the part. Now apply the 795 to the inside of the butyl tape. Why? Because the tape seals well never hardens and will keep the 795 from squishing out. Do not use very much 795. It will squish to the inside of the part and the tape will squish to the outside. Put just enough even pressure to get a good even squish and you're done. If using fasteners incrementally tighten each day just a little as the sealant(s) harden.

Once you get your mojo it's fast, effective, clean, and easy.
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Old 28-11-2012, 21:47   #19
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

Thanks, folks. 795 it is! MIGHT also consider the hybrid option, both butyl and 795. The dum-dum certainly is cheap enough. The windows are recessed, so no worries about catching an edge.
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Old 28-11-2012, 21:49   #20
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

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Butyl tape and 795 is a great combo
How is this better than just using one or the other ?

Quote:
MIGHT also consider the hybrid option, both butyl and 795
In your case you need the adhesive properties of the 795 to hold the acrylic.
Butyl is only a sealant, it will not hold anything in place, needs screws or bolts.
Butyl is also oily and I would be concerned that it might interfere with the adhesion of the 795.
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Old 29-11-2012, 06:06   #21
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Instead of butyl, use a double sided adhesive tape that is uded to attach mouldings to cars.
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Old 29-11-2012, 06:15   #22
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

The only problem I see with using a combination of VHB tape and dow 795 is that the tape is very thin, not allowing a thick enough layer of the 795.
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Old 29-11-2012, 06:47   #23
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

Quote:
Originally Posted by Ian R View Post
I tried using tape but had better results with 795 and small pieces of tape used to space and hold window in place until 795 sets. 795 fills any bumps , tape will pull the acrylic to the shape of the bump.
Did you use the 3M glazing tape? It has a high density foam core that comes in various thicknesses. It is certainly meant to fill small gaps as well as bridge small bumps. I guess if the window frame is very unfair, then one is better off with a liquid product.

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Old 29-11-2012, 07:39   #24
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

I used 795 on a hatch this summer with good results.
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Old 29-11-2012, 08:46   #25
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

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Originally Posted by NahanniV View Post
The only problem I see with using a combination of VHB tape and dow 795 is that the tape is very thin, not allowing a thick enough layer of the 795.
Butyl tape is thin but on the apps where I used it thick enough. I added the caulk to the inside to get a fill around bolt holes and a good squeeze to the inside rim.

795 and butyl are both very flexible thus for bedding parts where watertightness and flexibility are key it works great. Just another idea to keep in mind.

As to why its better? Butyl tape is easy to put a ring around stuff but much harder for complex and tight patterns. That's where the combo at times comes in handy. I even combine 5200 and tape sometimes. Just a small amount of 5200 to "Bind" better.
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Old 29-11-2012, 14:45   #26
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

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Originally Posted by colemj View Post
Did you use the 3M glazing tape? It has a high density foam core that comes in various thicknesses. It is certainly meant to fill small gaps as well as bridge small bumps. I guess if the window frame is very unfair, then one is better off with a liquid product.

Mark
The only tape I could find locally was 3M 4011 ( if I remember correctly ) which is only 1 mm thick so I used several layers for spacers.
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Old 29-11-2012, 15:03   #27
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

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Originally Posted by lateral View Post
Watching this thread with INTEREST! Just about to do my new recessed no fastener acrylic windows.
I beleive there is a paint you apply the same colour as the 795 to inside face of window to blank out any visible voids. Whats the trade name of this? Tips for new players?
795 must have to be applied accurately to get no squeeze out in the gap around window. (expansion clearance)
I guess the 3m tape will co$t 3 arms & legs?
Some paints can damage acrylic . I didn't use paint, just plenty of 795 and masking tape and remove excess.
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Old 02-12-2012, 11:15   #28
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

Don't get me wrong, I love 795 and it's what holds the glass windows onto my boat. It's easy to use and does not require a primer. But I have not had the same success as others using it on acrylic. When I re-glazed my hatches I initially used 795, but had a lot of difficulty getting it to adhere to the edges, even after sanding and cleaning them carefully. After redoing them twice due to leaks I switched to Sika 295 with primer and have had no leaks since. YMMV, but given my experience I can't recommend 795 for acrylic.
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Old 27-03-2013, 18:03   #29
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

NahanniV- not sure how long ago you did your project but I am interested to know if you have since had any issues with the Krylon Fusion paint.

Cheers
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Old 27-03-2013, 18:27   #30
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Re: Fixed window replacement - Dow 795 still the sealant of choice?

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NahanniV- not sure how long ago you did your project but I am interested to know if you have since had any issues with the Krylon Fusion paint.

Cheers
No problem so far. I did them in the fall of 2011.

Cheers,
JM.
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