Epoxy Blush development time

[jim_s]

I'm finishing up a floor replacement, and am finding myself under some time pressure to get the boat out of its current location. I need to finish tabbing the deck to the hull, then need to put down self-adhesive floor covering (Hydroturf with 3M self-adhesive backing, and Dap Weldwood around the edges). My question is, how long should I give the epoxy to cure to the point that it will no longer be producing blush, before I scrub off the blush, and then apply the floor covering? (While I'm in a rush, I don't want to rush it, and end up with floor covering that doesn't want to stay down due to blush continuing to develop while or after its being put down.)

I'm using Total Boat 5:1 epoxy with their slow hardener. The temperatures will be in the mid-80's, and the humidity will be around 50-60%. The 'Thin Film Set Time' for this epoxy/hardener is listed as 10 hrs at 75 degrees. The 'Thin Film Cure Time' is listed as 1-4 days. When I've been working with this epoxy, I give it at least 14-16 hours before the next coat, scrubbing the blush off before the next layer goes on, if I'm not able to do a wet-on-wet layup, and that has thus far worked well. (ie, everything has adhered well, is very clear, etc) I will note that it typically takes a full 24 hrs for it to lose all rubberiness, and get fully hard and a little more brittle.

Would 18 hrs likely be enough time before putting down the floor covering over the tabbed edges and seams between sheets? 24 hrs? several days? As noted, I'm under some time pressure, but not so much that I want to risk screwing the pooch at the very end of this project, by installing the floor covering too early.

 

[fhhuber]

If the epoxy is dry (not tacky) to the touch... its essentially done. Any blushing that will occur has occurred.

That doesn't say much about when its safe for the next application. You need to go by the directions. While it may be safe from blush, it may still have some chemical reaction still going on.

Someone who knows the exact products you are using may know shortcuts, but without that knowledge (or significant experimenting on scrap that you don't have time for) you need to just keep following the process you know works.

************

Floor covering can usually be delayed more easily and with less negative side effects than trying to glue it down too soon.

 

[alldodge]

Have not used this brand and there isn't a lot of info about how to use it so far as reapplication. The type I use says the blush needs to come off IF (notice the IF) blushing has occurred. It specifies a set time

Set Time:[SIZE=-1]This is the amount of time after the epoxy is applied in a thin film that it will arrive at a gel state, still wet, but no longer a liquid. To recoat without sanding between coats you must reapply after this point but before the drying time has completed.[/SIZE]

So I'm thinking that your epoxy should be able to recoat after its set time of 1-4 hours, but can find no proof. You could call JTD and ask them since it is their product
http://www.totalboat.com/wp-content...aditional-5to1-Epoxy-Resin-Technical-Data.pdf

 

[Chigwalla]

Set time is gel time: the resin is thixotropic and is no longer self-leveling. You can move pieces off the workbench but you can still dent the resin with a fingertip.
Cure time is hard to the touch. Epoxy will continue to cure internally for a long time (like concrete).

Give it 24 hours to get rid of that 'rubberiness' before gluing anything on top of it.

 

[jim_s]

Finally got in touch (I'd left them a help message a day ago, but hadn't heard anything, so ended up calling...). They suggested a minimum of 24 hours. They said that under ideal conditions (ie, no tight time constraints), several days would be their recommendation, but that if I'm under time pressure, 24 hours should be sufficient.

Thanks for everyone's info and advice! (and extra kudos to Chigwalla for nailing it!