I am stepping into the vac bag world after watching from the sidelines for some time. I have found most of the answers to my questions on setting up the system and I tested it making some foam core glass on fins…
Now its time to glass a board with it. It is an EPS blank and I will be using RR epoxy…
Here is the plan…
Prep blank by sealing with micro-balloon slurry???-havent found a consensus…should I do this? I really don’t want pinholes and would like to achieve a glossy finish with the least amount of sanding possible…
Wet out cloth on wet out table, then squeegee onto board.
Apply perforated peel ply, tape in place if necessary
Wrap with bleeder cloth
Put in bag and vac at 8-10 in Hg.
Some have suggested just bagging without peel ply and bleeder, I don’t see how I will get a complete vacuum doing that…
I’ve sealed all mine, with the idea that it will keep weight down and avoid saturating the core and making it a stiffy. The first was sealed with epoxy/balloon mix=very nice. The others with spackle for airbrushing=good art, no drama, no delams etc. I know there is concern about the bond, but I have not had any trouble.
Josh, you didn’t mention pinholes or any other issues with either method. Are you talking about sealing for a traditional layup or for vacuum? I too have had great results with spackle for my airbrushed graphics, but I am not sure it will stop the blank from releasing air into the glass when I pull vac. Thanks, ben
There may be issues if the lam is dry in some spots, but no gassing problems at all, that is the beauty of laminating under vacuum. if there were any air/gassing it would make its way out and the glass would be pressed against the core. Now, it is possible to trap air. I had this happen to me because the perf release wasn’t flowing(i attempted to make my own)and air got trapped…also got air trapped under my lam, bummer.
I have done it two ways… lam bottom bag then lam top and bag. the other way was to bag the whole thing in one shot, i prefer this method, it is more stressful but I like the idea/process/challenge of a single stage bagging. a word of caution, bagging it all at once is not for the faint hearted, and having a plan and dry runs help with success. You are more likely to trap air, crease the cloth, curse, and abuse the cat. After some dry runs I decided to bag it all for my first try, and I was more than happy with the results. With a dry run you can refine your technique. check for areas that trap air, leaks, time yourself, etc.
take pictures, correction, get someone to take pictures…
Okay, gave this a try tonight. Not totally happy with the seal I am getting on my bag. Pump cycles every minute or so. Had to track down a lot of leaks at the beginning. In the future I will be sure to keep my breather material a good distance away from the ends of the bag so it will tend to seal itself.
I decided to lay down a carbon strip for a stringer on this board. I could well have vac’d on the glass at the same time, baby steps for now though…
Here is a play by play for those interested…
Layed out the carbon fiber…if you tape it to one end and stretch it, it will lay down straight
Mixed epoxy and brushed it on with a chip brush, to prevent accidentally moving cf
layed perforated peel ply over cf/resin, then breather on top of that
Put entire mess into bag
sealed bag and pulled vac
Its still in the bag now, I will post pics when I take it out, for now here are some attachments of the bagging…ben
Here are some more progress pics…I am taking advantage of the time off work with the fires to get this board lammed…I vac’d on the bottom glass this morning.
I used 6 oz glass and resin research epoxy, with perfply and bleeder wrapped around that. I then bagged it and vac’d at 11 in Hg. It was kinda stressful (Using the fast hardener), but I managed to squeeze off a few shots at stages where I was changing gloves…hope someone is getting something from this…ben
The problem that bugged me the most when starting to do vac bags was the pinholes I kept getting in the glass. I was thinking it was bubbles in the resin but after doing a load of research on the net and in books I found out it’s actually a result of the glass I was using.
The term that the composite guys seem to use when talking about this issue is porosity. This depends on the weave and thread density of your fabric. Off the top of my head the order of porosity for weaves is satin, twill, plain with plain being the most porous. It’s also the weave typically used for glassing surfboards. If you use a lighter weight fabric you will tend to get a less porous laminate too. If you’re in the US thayercraft does some really good value 0.5oz cloth. I haven’t found anywhere cheap in Europe yet.
The other problem I had was creasing at the centre rail. Ended up with a big crease which I had to sand off leaving a break in the glass all the way along the middle of the rail. This is obviously going to lead to a really weak board. The best thing I found to stop getting creases in the rail was to use loads of padding around the rails to stop the bag pinching as the vac gets pulled down. I’m going to use a thick winter duvet for my next go, I think that should cure the problem completely. Got to get a new wetsuit and get my car back on the road before I can do any more board experiments though, so it may be a while before i try it out. Be interested to hear how you get on with rail creases on your board.
Well, here are the pics of the board post bag. I didn’t have any trouble with the lam getting pinched on the rails. The bleeder seems to prevent that from happening.
I think that Muhleder may be on to something with the cloth weight/finish being important to a pinhole free surface. The bottom was done with 6 oz and a 1:1 resin:cloth ratio, pinholes galore, but a nice tight lam. The top I did with 6 oz and 4 oz. The 4 oz I put on top. This produced a finish with no pinholes. I did lay this up with a lot more resin though. Probably about 1.5:1 or so. Unfortunately the deck showed the imprint of the bleeder. I think this is because of the increased ratio of resin I used.
I think in the future I may try to put the bleeder on the opposite side of the one being lammed. The lam would be wrapped in peelply and any trapped air could be sucked through the board instead of through the lam. And the smooth surface of the bag would leave a perfect finish on the board. Has anyone tried this? Would love to hear a full recipe for how a smooth lam is produced. ie, resin used, glass used, substrate, peelply type and perf or not, bleeder positioning, and vacuum pressure used.
Here are couple of pics of the lammed board ready for filling/ sanding.
Bottom, I don’t think the picture really shows the pinholes, trust me there are thousands.
Deck, I should have been more anal about getting the creases out, but since the gass was tight it is just resin that I can easily sand off.
Would like to hear suggestions at this point…thanks ben
