Vac table surface

there are zero bubbles - this epoxy is the one that bubbles almost not at all

I think the best bet is to sand it flat and put another 48 oz of epoxy on it (perhaps a medium hardener) and cover it with stretched vac film, like rx suggested.... I think I could probably make the stretcher on my cutting table and with a few helpers flip and move it over and set it on the 33 foot long vac table. Maybe run a buffer over it and call it good.

 

Yes but the other coatings aren't.

You've embarked on the labor intensive and costly method of making a table, I was hoping to cut out some of the cost and time for you.

 

I epoxied the table a second time and tried to apply release film to it. Well, the release film was sort of lost in the process as it sheared in about 3 places and I removed it all and rerolled the epoxy.

I sanded the 2nd coat of epoxy (now 96 ounces) down today to 400 grit and I'm waxing the table. Going to do a few tests, but I'd say the table is pretty smooth at the 400 grit rating.

I was going to paint it, but the paint will be more dust impregnated than a table sanded to 400 grit. The only thing to worry about is epoxy degradation. Gotta get my boat built!

 

Well I guess you are out of luck but I am glad for you it's finally over.

I don't know what caused the problem but the nylon film we are using is very tough and hard to break (nylon becomes brittle after being stored for a long time). It is transparent green in color. We have even used flimsier film like cellophane for poly resin. We glue it on a frame, spray a mist of water on the surface, dry it out in the sun, and comes out drum tight. We are very careful lowering it though. It is a two man job.

We have used this technique even for synthetic granite. Aluminum trihydrite is very coarse and must be manufactured on a flat surface for flat panels but when it is not possible, we sprinkle ATH granules on the surface (can also be sprayed), apply a really thick coat of resin until it levels off, then finish it off with more resin and the stretched film technique. I worked a long time manufacturing synthetic stones, granite, and marble surface, thus we have to build a lot of flat tables or do it the opposite way.

 

It's too late now, but for a temporary table can't a person stretch some polyethylene plastic sheeting (Visqueen) over it? That would leave the table materials pretty much in their original state (except for screw holes etc) for re-use in some other application.

 

This is what i have done in the past,spray glued it down to the table then my vac bag gets taped to the vapor barrier (visqueen) parts come out flat and no need for release films.

 

I had built two sides only frames using 1x3s and had four people to move them, but the frames I made were 32' long and rather saggy and I had stapled the release film to the frames and when they sagged, the film ripped on my staples just as we were moving it over the top of the fresh epoxy. A more rigid and glued frame would have been the ticket. The regular vac bag film had too many waves and lines in it to use.

Honestly I didn't account for the release film to break at the staples. Live and learn.

On a do over, I'd build a better frame and glue it on.

 

As a matter of consolation, I have never built a frame that size. Most is at 12-16 feet and I used stiff metal frames. That is quite monumental and I have doubt you can stretch the film evenly at 32 ft. Tungsten and Samsam proposal might work.

 

If you haven't done it, you should seal all sides of the MDF, MDF will absorb moisture from changes in humidity and distort the surfaces if you don't. For short term use it's not needed, but is recommended for long term.

 

That's what I was thinking. First tape over the table seams with some clear tape, or foil tape, and then the plastic. The panels are usually filled and faired before painting anyways so the tables don't have to be perfect.

(I wrote this yesterday to be post #22 but forgot to actually hit the button and post it)

 

Thanks ondarvr. I have not done so. I will sand the wax off and roll some epoxy on it.

When you wax the table; do you guys remove or polish the prior coat or do you just keep rolling more coats on? It seems a little silly to polish the wax when I want a build up for release.

 

What wax are you rolling on?

 

mold magic - carnauba

 

How do you roll it on?

But back to your question, yes every coat needs to wiped off and polished by hand.

 

I put it on with a Wen rotary 6" wax tool. I had my friend applying it as fast as he could go and I just kept moving the waxer on halfsies (if you will). I did not remove the last coat and simply just went over it again. It seemed foolish to remove the wax if the epoxy bond would be reduced by doing so, but I wasn't really super sure. We have 3 coats on it now, but the last two weren't polished out. I use the waxer, by putting clean cloths under it for the polishing, but I need to knock it down a bit with a sponge with a little mesh on one side, otherwise it won't really polish. Would the epoxy stick if the surface were waxed, but unpolished? I was going to put a thin coat of epoxy right onto the table before I put my fiberglass down and used more epoxy for the wetout. My first two pieces tomorrow are 10" wide by 8' long.