cure time for sanding

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ToddM
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cure time for sanding

Postby ToddM » Wed Sep 20, 2017 6:30 pm

I have encapsulated some Doug Fir pieces with System Three Silver Tip. Any opinions on how long to cure until I can sand without clogging up my sandpaper with globs? I plan on using a random orbit sander with 150 grit to flatten the epoxy and scratch it up a bit for painting. Many products give a cure time until sanding, but I have noticed that sanding without a lot of wasted sandpaper and frustration usually needs a longer cure time. What is your experience?

Thanks in advance.

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chugalug
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Re: cure time for sanding

Postby chugalug » Thu Sep 21, 2017 5:51 am

:D Unsure about system 3.I used Glen-L's Epoxy Shield and waited at least 2 weeks after final coat of epoxy on hull.Just have to keep checking and testing sander after. :D
Working on regular-sized Bo-Jest


"If it's not crooked,It's not mine

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Jimbob
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Re: cure time for sanding

Postby Jimbob » Thu Sep 21, 2017 8:16 am

Hi Todd,
I use system 3 silver tip epoxy. I have usually waited overnight. You might check the instructions on the bottle, they usually state a "full cure" time.
Also the nice folks at Jamestown Distributors will have someone in their paint/epoxy department that can give you good advise.
Jim
Jim Neeley
Sacramento, CA

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BayouBengal
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Re: cure time for sanding

Postby BayouBengal » Thu Sep 21, 2017 8:19 am

Once I begin mixing epoxy by weight instead of volume, I was generally able to sand SilverTip epoxy the next day. Your paper clogs because you have trace amounts of either unreacted Part A Resin or Part B Hardener on your epoxied surface. Both are syrupy until chemically reacted with the other; so, will clog your paper. If your epoxy is not mixed accurately, you could honestly wait for a year to sand it and still experience clogging. The free SystemThree Epoxy Book that can be downloaded from their site explains this and stresses the importance of mixing by weight.

JimmY
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Re: cure time for sanding

Postby JimmY » Thu Sep 21, 2017 9:19 am

I used the System 3 Silver Tip with the metering pumps, never had a bad batch and sanded after 24 hours. People told me to wait 2 weeks before painting (System 3 WR-LPU), but I was always too impatient and typically painted after a day or two with no issues. YMMV

I sanded to 220 for painting, and if this is outside surface (hull, deck) I used a long board to make sure the epoxy was flat and level. If it in a hidden interior space, this probably isn't necessary.

The key to a good paint job is surface prep!
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

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Bill Edmundson
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Re: cure time for sanding

Postby Bill Edmundson » Thu Sep 21, 2017 9:46 am

This is how I usually work:
Day 1
Glass side 1.

Day 2
Glass side 2 and fill coat side 1

Day 3
Glass bottom side 1 and fill coat 2 side 1 and fill coat side 2

Day 4
Glass bottom side 2 and fill coat 2 side 2 and fill coat bottom 1

Day 5
Fill coat 2 bottom 1 and fill coat bottom 2

Day 6
Fill coat 2 bottom 2

Day 7 & 8
I'm tired of doing this! God and I need a rest.

Day 9
Side 1 is now six days old and I can start sanding side 1.

Some place I did the transom.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

ToddM
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Re: cure time for sanding

Postby ToddM » Fri Sep 22, 2017 7:35 am

A couple of days ago, about 48 hours after application, the epoxy may have been a little tacky, so I wrote this post to get advice. Yesterday, about 96 hours after application, the epoxy was definitely no longer tacky, so I started sanding. It sanded like a champ, with no clogging up of the sandpaper. It flattened so nicely and with so little effort that I decided to put on another coat of Silver tip, this time not quite so heavy.

Thanks for the advice, and here is a photo of the 2nd coat.

IMG_0945.JPG


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