cure time for sanding

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cure time for sanding

Post by ToddM »

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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Re: cure time for sanding

Post by chugalug »

: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

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Re: cure time for sanding

Post by Jimbob »

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 Neeley
Building a Barrelback in Sacramento, CA

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Re: cure time for sanding

Post by BayouBengal »

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.

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Re: cure time for sanding

Post by JimmY »

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.

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Re: cure time for sanding

Post by Bill Edmundson »

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.

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

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Re: cure time for sanding

Post by ToddM »

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.

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