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Glassing

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Old 04-02-2012, 08:30 AM
  #1
rcpete347
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Default Glassing

HI all, need help in glassing a wing, the first coat, always looks great, but the second coat, always separates1 hour , after applied. It separates and puddles.
First coat is 3/4oz cloth, with Pacer finishing resin. Second coat is just Pacer finishing resin, applied after sanding the first coat., several days later.It looks like the second coat does not like to bind to the first coat. This is a problem, I have had for years.
Any help would be appreciated.
Rcpete
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Old 04-02-2012, 08:37 AM
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Default RE: Glassing

When and how are you adding the second coat?

I always allow the first coat to dry completely, then lightly sand with 220 or 320 grit. Clean all the dust completely then brush on a second coat of resin, and squeegee it off as thinly as possible. Works great with West Systems epoxy, not sure about Zpoxy.
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Old 04-02-2012, 08:41 AM
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Default RE: Glassing

Hello again Pete,

I always apply the first coat using a playing card to scrape the resin and flatten the cloth. press just hard enough to remove most of the resin, but not so hard that the cloth is left dry and does not stick.

i do the second coat the same way with a playing card pressing pretty hard with the edge of the card. this removes all the resin, but pushes the second coat down into the glass poores.

brush coat of K-36 sanded 99% off - BVM pinhole filler, followed bt a spray K-36 and its smooth as silk.
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Old 04-02-2012, 08:41 AM
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Default RE: Glassing

Allow 6 to 8 hrs for the first coat to dry hard, if it's gummy you will have this problem, sanding before it has hardened is not a good idea...
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Old 04-02-2012, 08:41 AM
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Default RE: Glassing

Why the second coat? Once you've saturated the glass on the first coat adding a secind coat only adds weight.
I'd fill the voids with K36 (or similar) , which sands so much easier than Epoxy.
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Old 04-02-2012, 08:42 AM
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Default RE: Glassing

You may want to change over to laminating resin. Laminating resin is intended for multiple applications. West Systems is a good way to go and redily available but there are many other good products out there.
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Old 04-02-2012, 08:49 AM
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Default RE: Glassing

Pete,

Do you thin your resin at all? I used Z-Poxy (until I discovered West System) thinned down 50/50 with denatured alcohol and brushed on. It takes half the time of the playing card/squeegee method, and in direct sunlight dries incredibly fast. The second coat is also thinned to the same ratio and allowed to thoroughly dry. It sands perfect.
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Old 04-02-2012, 08:58 AM
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Default RE: Glassing


Quote:
ORIGINAL: FalconWings

Why the second coat? Once you've saturated the glass on the first coat adding a secind coat only adds weight.
I'd fill the voids with K36 (or similar) , which sands so much easier than Epoxy.
Agreed, one coat for me, then polyester primer, sanding epoxy sucks!


http://www.eastwood.com/featherfill-g2-gray-quart.html

This stuff sands like butter
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Old 04-02-2012, 09:41 AM
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Default RE: Glassing

HI Guys, thanks for the info, will give West systems a try, since I use it for every thing else.
Thanks Rcpete
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Old 04-02-2012, 09:45 AM
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Default RE: Glassing

Rich

Don't hold back! Tell us how you really feel about sanding Epoxy!

Bob
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Old 04-02-2012, 11:42 AM
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Default RE: Glassing


Quote:
ORIGINAL: FalconWings

Why the second coat? Once you've saturated the glass on the first coat adding a secind coat only adds weight.
I'd fill the voids with K36 (or similar) , which sands so much easier than Epoxy.
Only one coat then prime with k2 and sand. easy
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Old 04-02-2012, 11:50 AM
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Quote:
ORIGINAL: Meesh

Rich

Don't hold back! Tell us how you really feel about sanding Epoxy!

Bob
No problem Bob...
I learned to hate sanding at a young age, my first job out of High School was painting these bad boys
After a couple of years of doing that I decided to go to college for my BS degree
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Old 04-02-2012, 12:29 PM
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Default RE: Glassing

Hi,

Thinned West System sands easily to powder. I've never looked back....
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Old 04-02-2012, 01:05 PM
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Default RE: Glassing

I have always used the West System laminating epoxy and have not seen what you are experiencing.  I put on the first coat and squeegy off the excess resin.  For the second coat, I mix in micro ballons until the resin is a slightly runny paste.  Apply this and squeegy off the excess.  The micro ballons fill in the weave of the cloth with very little weight gain.  Wet sand with 400 and it's ready for primer and paint.  Never had to use pin hole filler since I've started adding micro ballons to the second coat of resin.

Kirk
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Old 04-02-2012, 01:07 PM
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Default RE: Glassing

k_sonn, I was just going to post the same thing about adding micro balloons to primer. I recently starting doing this and its a nice way to thicken up the primer for filling where you need a little extra buildup. Its a great idea and wish I knew that trick years ago.
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Old 04-02-2012, 02:12 PM
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Default RE: Glassing

Pete your problem is something called amine blush. See [link=http://www.oneoceankayaks.com/Epoxresl.htm#blush]clicky[/link] for a good is little dated expo on the subject.

I had this also and solved it by going to a laminating resin for the first coat[s] and finishing resin for the final coat. I had success with the early West System varients 206 and 207 without sanding between coats just rolling them on with foam rollers then wiping down with acetone followed by water but you might want to try a test piece first. At that time I was going for a clear finish on glider wings.

My F 104 was the last thing I glassed and that was with West System but would have been 6 years back now so formulations may have changed.

West advice on the topic here. [link=http://www.westsystem.com/ss/problem-solving/#fish-eyeing]clicky[/link]

Basically if you can wet sand without getting a 'water bead' then you should be good to go.
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Old 04-02-2012, 03:34 PM
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Default RE: Glassing

Here is a great shot of the epoxy separating


Click on pictures for detail
This picture shows the fiberglass weave after squeegeeing the first filler coat (MAS epoxy). This is how it should look but it doesn't last long because it was put on top of barely cured substrate only 3 hours later.

The hardener is a blend of 20% fast and 80% slow
.
This is the same patch of surface as in the picture above only few minutes later. I am puzzled by this myself but it seems like the uncured epoxy wants to repel the new coat in the same way a new car polish beads up water. Good ol' surface tension at work.
This 'beading' actually became an advantage because the next filler coat really filled the deep valleys between the high beads and it saved me from applying the last coat. It took 3 coats in total to cover the deck.

Thanks ,great clicky, on the epoxy, J. duncker
Rcpete
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Old 04-02-2012, 04:13 PM
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Default RE: Glassing

I only use one coat of resin while applying the glass cloth. After that, I just spray on a few coats of primer, sand it smooth, then paint. I feel that a second coat of resin dries too hard to sand, and ends up giving you the problems you have.
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Old 04-02-2012, 04:23 PM
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Default RE: Glassing

I have always used the 2 coat process with west system. It is what you want to do if the plan is to flite metal or presto because you are cutting the material on the surface and want a hard shell . Dan
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Old 04-02-2012, 06:02 PM
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Default RE: Glassing

Learned a lot from that link on epoxy blushing. For what it is worth, I wipe down the raw epoxy surface with alcohol before I start to sand. Takes away most of the tacky feel that destroys sandpaper before you even get started when using laminating resins that are air dried.

Dan
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Old 04-03-2012, 12:53 AM
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Default RE: Glassing

I didn't know alcohol worked, I have used MEK to wipe down before sanding with good results. I'll have to try alcohol, much more user friendly.
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Old 04-03-2012, 04:00 AM
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Default RE: Glassing

Pete,
I have seen this before. Epoxy and polyester resin have styrene (wax) added to it for curing. This floats to the surface to isolate the air form the chemical reaction so you get a 100% cure. If the epoxy is not isolated the epoxy will be tacky to the touch. This is good if you are doing multiple lay-ups because you will get a chemical bond instead of a mechanical one. But you still need epoxy with wax in it for the final lay-up. The epoxy will not stick to the wax and must be sanded off before you can add a second layer. If you don’t sand off the wax it will be like the wax on your car, the water just beads up.
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Old 04-03-2012, 04:21 AM
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Default RE: Glassing

man, you guys are doing it the old-fashioned elbow-grease way... I quit doing that 2 years ago!

Go get some 100% pure polyester DRESS liner fabric from your local fabric supply store.

Fiberglass your part using whatever glass cloth, epoxy resin and your preferred method of application.

once your done (only squeegee off the excess Puddles of resin, not the entire surface. A little extra resin can be left on the surface)
Lay down the polyester dress liner on the part and smooth it down using a squeegee (if your cloth has a crease in it, throw it in the dryer for a minute or 2). then LEAVE it on till the epoxy has cured.

The next day, pull off the dress liner and throw it away. Your left with a surface ready for paint, no sanding required!

Also, if you have an area of fiberglass that peels away from the surface, take a plastic baggy, put your finger in it, put a drop of thin CA on the lifted fiberglass, then rub the CA into the fiberglass with your plastic wrapped finger (keep it moving, you'll feel it warm up, at that point you can stop).
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Old 04-03-2012, 05:03 AM
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Default RE: Glassing

If you use a roll of toilet paper and roll it over the first coat of resin/epoxy it will soak up the excess bonding agent while pressing the cloth to the wood. With each pass the wet paper has to be disposed. No bubbles or high spots in the cloth and no excess fluid left in the cloth. Second coat of resin/epoxy should be cut to make it flow. Use a guid coat of laquor to sand the high spots out.
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Old 04-03-2012, 05:30 AM
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Quote:
ORIGINAL: handyman 220

I didn't know alcohol worked, I have used MEK to wipe down before sanding with good results. I'll have to try alcohol, much more user friendly.
Yes, alcohol works very well. Especially when you drink it ... makes the time go by faster.

Time flys when you're having rum!
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