Tack rag

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bob smith
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Tack rag

Post by bob smith » Sun Oct 06, 2013 6:05 am

What do you use as a tack rag between epoxy coats?
Bob Smith
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Bob Smith
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billy c
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Re: Tack rag

Post by billy c » Sun Oct 06, 2013 8:34 am

water
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galamb
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Re: Tack rag

Post by galamb » Sun Oct 06, 2013 10:40 am

Nothing if I am over coating while the epoxy is still green.

If it's well set-up but not fully cured then I use plastic (steel) wool, 0000, scrubby pads (a generic version of "Scotch Brite") and then rinse off with water.

If it's totally cured then you really should sand with 80 grit (then water rinse) to give the next coat something to "mechanically" affix to...
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Bill CNC
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Re: Tack rag

Post by Bill CNC » Sun Oct 06, 2013 11:16 am

bob smith wrote:What do you use as a tack rag between epoxy coats?
Bob Smith
Chester, SC
Bob,

If you sanded it, ... then use a "Tack Rag". They can be purchased anywhere you buy paint and they cost about a buck. If it's still green, your good to go as previously stated.

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billy c
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Re: Tack rag

Post by billy c » Sun Oct 06, 2013 1:53 pm

sorry ...but you do NOT tack rag between epoxy coats!
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Bill CNC
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Re: Tack rag

Post by Bill CNC » Sun Oct 06, 2013 2:08 pm

To lift the dust, ... um I do, I just lightly dust with it with no hand pressure. It picks up the fine dust before I coat it. I make sure I don't use a fresh rag but one that has been used to remove primer dust so I dont contaminate the the surface with a soggy tac rag. I haven't had any issues doing this.

I should have clarified the process in my other post.

Why would you not use a tac rag?

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billy c
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Re: Tack rag

Post by billy c » Sun Oct 06, 2013 2:23 pm

from the system 3 epoxy book
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Screen shot 2013-10-06 at 5.22.48 PM.png
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Bill CNC
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Re: Tack rag

Post by Bill CNC » Sun Oct 06, 2013 3:01 pm

Hi Billy,

Ok, that is with Systems 3 which I don't think I have used that brand. The scary thing is it says to use compressed air and not to use acetone. I would be more concerned with the compressed air shooting oil particles at the surface, and I certainly would not use an air hose if I could not use a chemical cleaner such as acetone or alcohol.

I use West, US composites and a few other specialty brands and have never had an issue using old tac rags. I think common sense when looking at a fresh tac rag should come into play here. I have had some almost dripping, and I have has some that where pretty dry. When buying them, you can tell the difference just buy looking at them and the plastic wrap they come in.

Funny thing is, ... everything that could possibly effect epoxy would effect paint, ... yet, ... what are they used for? I think the issue comes in to play here is the pressure. When wiping a paint job, your using great care not to mar or scratch the surface. With freshly sanded resin, I think more people apply a lot more pressure as they are not worried about scratches or marring and are more or less scrubbing the surface.

The poster never specified what brand of epoxy they where using, ... something I should have asked.

Bill
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galamb
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Re: Tack rag

Post by galamb » Sun Oct 06, 2013 3:02 pm

I think we are kinda playing with words here.

At least by the definition of "tack rag" I found with a google search it lists it as a rag that has a tacky substance (petroleum product) impregnated in it to allow it to pick up fine dust etc.

So, no, I wouldn't use a "tack rag" because you don't want any foreign substance on your epoxy if you are going to re-coat.

What (we) should have said is use a clean rag or a shop towel (like those blue jobbies that are about 4 times as thick as paper towels) - but nothing that could potentially contaminate the surface.

As has been stated here, if the epoxy is "green" (might feel a little sticky still or you can easily dent it with your finger nail) then you can go right over top of it with no additional prep. That period of time could be anything from an hour to many hours after your first lay up, depending on the hardener you used, the air temp etc.

If it's been say 18 to 24 hours you may notice some blush on the epoxy (most epoxy that claims "no blush" still ends up with a waxy substance on the surface). That must be "washed" off - that's where I use the scrubby pads.

Epoxy "cures" in anything from a couple of days to maybe a week. If it is fully cured I sand it, then wash it off (hose if we are talking something like the hull) then wipe it down with clean cloths before applying more epoxy.

If the surface isn't dry your fresh epoxy takes on a milky appearance. I have had this happen with humidity and while, when cured, it doesn't appear to affect the strength, if you were clear coating you certainly want to avoid it.

Likewise, when I wipe off, unless it will be clear finished, I don't get super irritated by a little dust or saw dust etc - it wouldn't bother you to add wood flour (saw dust) to your epoxy as a filler, so I don't sweat it unless it on a "clear" surface.

The big thing you want to remove is any of the blush or other waxy/oily contaminant that would hinder the bonding of the epoxy.

When "filling" cloth the easiest way to do it, is start early in the morning on a decently nice, low humidity day - use a quicker hardener, and over coat the soon as feasible. Even up where I live (Eastern Ontario), I can easily get three coats down on a nice day which is often enough to completely fill in a 6oz fiberglass cloth...
Graham

Yes, Plywood is "real" wood :)

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

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billy c
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Re: Tack rag

Post by billy c » Sun Oct 06, 2013 3:14 pm

yup i think we are all concerned about the same thing :D
....agree 100% with the compressed air being maybe even worse than the tack rag
best thing i do for myself ...and avoids lots of words later is wet down the sanded surface with water and make sure the water does not bead off before commiting to the next coat.
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Bill CNC
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Re: Tack rag

Post by Bill CNC » Sun Oct 06, 2013 3:24 pm

We're looking at this the same, but from different ends. I avoid water until the 3rd coat. I dont want to chance moisture getting into small pin holes. If that happens, I have to wait a few days for it to dry out otherwise you risk blisters and fogging. Acetone or Alcohol will evaporate within minutes letting me progress much faster because I always sand between the 2nd & 3rd coats. Other coats, I go by feel whether I'm going to sand it or not, or if time doesn't permit continuing without sanding.

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TNT Build, ... On Going, ... http://tinyurl.com/abmae64

The Freebie Zip, ... On Going, ...http://tinyurl.com/at3udss

Super Spartan Build "Miss Tripindicular", ... Completed, ...http://tinyurl.com/b488wsz

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