Getting a smooth finish over Kevlar.

[kampkurz]

Looking to achieve a smooth, paintable finish over an epoxy/kevlar/foam composite. I've seen some good looking stuff out there. Any suggestions? Thanks

[heumanntouch7]

if you're not concerned about weight I would recommend Evercoat G2 polyester primer. it is very very high build stuff and surprisingly flexible. id say two or three medium-heavy coats and block sand it you will be smooth as glass.

[kampkurz]

Still looking.

Okay, I wish I'd a had a clogged inline filter. Anyone else have any suggestions for smoothing kevlar for painting. Has anyone ever tried skim coating with bondo? It's not too large an area, so quick and light are best.
Thanks in advance. KampKurz

[Bill Huson]

Okay, I wish I'd a had a clogged inline filter. Anyone else have any suggestions for smoothing kevlar for painting. Has anyone ever tried skim coating with bondo? It's not too large an area, so quick and light are best.
Thanks in advance. KampKurz

NO BONDO! Yeah, it would work for a bit, then fall off. Bondo sucks for boats. I usually skim rough spots with WEST and #407 Fairing Filler. If it's real rough use a notched trowel - easier to sand flat, then go back over with another coat with a flat trowel to fill in remaining notched trowel grooves. But for just cloth weave fill, a loose WEST/407 mix with a spreader should do the job.

[RTM]

I never used it over Kevlar, or even on a race boat but I skim coated an entire 14` fiberglass antique boat that was full of spider cracks, nicks, holes and gouges. It is basically a very thin bondo like material that is made for filling nicks and gouges in car bumpers. It really works well, is simple to use if you enjoy sanding, and gives a slick surface. About $35 a bottle. Buy it at Automotive paint stores.

http://www.evercoat.com/productDetail.aspx?pID=8

Rich

[Bill Huson]

I never used it over Kevlar, or even on a race boat but I skim coated an entire 14` fiberglass antique boat that was full of spider cracks, nicks, holes and gouges. It is basically a very thin bondo like material that is made for filling nicks and gouges in car bumpers. It really works well, is simple to use if you enjoy sanding, and gives a slick surface. About $35 a bottle. Buy it at Automotive paint stores.

http://www.evercoat.com/productDetail.aspx?pID=8

Rich

Sounds like the stuff I've used called "Featherfill". It was like bondo but much thinner and required tedious mixing with an electric drill and paddle. Featherfill was sprayed on - first coat horizontal pattern, wait til it "flashes", second coat vertical. Very easy tro sand, hid all sorts of minor imperfections and sand scratches. Of course this was on cars - can't recall if I ever tried it on a boat. I wouldn't use it on a boat that spends lots of time on the water, like a recreational fishing boat or the like, but a race boat is low hours wet so I figure one can get away with all sorts of finish tricks that wouldn't hold up in the real world of the Big Blue Sea.

[johnsonm50]

As far as for a race boat & its stresses [even for the short time it is in]. Im thinking the 407 & West method to be best. In the end it wont add much weight & instead of sticking & hanging on like other products meant to fill it will be an integral part of the kevlar composite. If you want more strength West 404 filler is higher density so of course more weight too. The notched trowel idea is good if you have to create a surface from the very ruff. If not so drastic you could sqee-gee or even roll it on. Theres alot of past writing on West products you could review & information on what to choose on related West System sites. Good Luck.
PS. If they made a mix that would cure 'etched' & ready for a finish coat varnish/paint after a long time, they would have the best thing going better, but not yet. Getting that finish ready sanding done without cutting thru can be tuff.

[RTM]

Bill,
This stuff behaves just like thin bondo. You have to gauge how much hardener to mix in, very little, and spread it quickly as it sets up just about like bondo, and is as difficult to sand. Big thing is the flexibility when set is unbelievable if you leave some on a flexable spreader it won`t come off, either sand it off or get another spreader. I believe plastic car bumpers suffer from more vibration and bumps than any race boat and for a long period of time. I really like this stuff but it is not real easy to use over a big area becuase only small amounts can be spread on at a time, becuase of quick set time. Spreading it over a flat piece of Kevlar around a cockpit would be easy.
Rich

[johnsonm50]

[QUOTE=RTM;161936]Bill,
This stuff behaves just like thin bondo. You have to gauge how much hardener to mix in, very little, and spread it quickly as it sets up just about like bondo, and is as difficult to sand. Big thing is the flexibility when set is unbelievable if you leave some on a flexable spreader it won`t come off, either sand it off or get another spreader. I believe plastic car bumpers suffer from more vibration and bumps than any race boat and for a long period of time. I really like this stuff but it is not real easy to use over a big area becuase only small amounts can be spread on at a time, becuase of quick set time. Spreading it over a flat piece of Kevlar around a cockpit would be easy.
Rich
It would work fine Im sure for what its made to do. I would advise double checking whether or not a polyester based filler is compatible with the epoxy holding the kevlar together. I have seen somewhere that polyester resin should not be put onto epoxy resin. Could it be the same problem with a poly filler?

[reed28n]

kevlar

have you already laminted the kelar to the surface? and know trying to fill?

[kampkurz]

Smoothing Kevlar

I had already laminated the kelar to the foam, I scuffed it with 80 grit, then, as suggested earlier in this thread,(thank you) spread 407 thickened epoxy over the surface, smoothing with a plastic trowel. Lots of sanding, but it turned out real nice considering it was my first such project.
It was a UIM compliant 'throttle guard' for an OSY hydro. It might be seen in Depue this weekend, or maybe ripping up the region 1 ovals.
Thanks again to those that posted in reply. Hydroracer is as wonderful a tool as any in my box, sometimes. Kampkurz

[Team B&H]

You can save a lot of effort here if you would use a piece of thin plastic sheeting over the kevlar when you laminate it up. When the epoxy is wet, put the thin plastic sheet on and squeegee well to get out the air bubbles and wrinkles. Let cure and when it is hard, just pull off the plastic and you'll be left with a glass smooth surface. Kind of late for that now but you should try it on your next project. Will be in Depue later this afternoon so will hopefully have a chance to see it.

Sam

[kampkurz]

Plastic sheeting??

Is there a plastic that performs better than others? I do remember you telling me a little about that, and let it slip from memory. Sure would seem to save some time.

[modhydro]

Kevlar finish

This works on any fabric. Instead of plastic sheet you can use peel ply or if you want to save some money, simply use polyester fabric from a local fabric store. They usually have a sale rack with it very cheap. It is like the stuff from a windbreaker jacket. It works easier than plastic since the air bubbles can come up though the cloth when working it with a squeege. Another neat thing with the peel ply is that it will hold cloth to the substrate in curves that normally would bridge. It is by no means vacuum bagging, but you would be surprised at how much curvature it will hold cloth to.

I will see you this weekend and we can talk more.

Steve Roskowski

[Dave M]

More Fabric

To add to Steve's post, I use 100% Nylon, it seems to release a little more easy after cure.

Wal-Mart usuallys has it on clearance racks for less than $1.00 a yard, typically in 36" wide rolls. Colors vary.

I think the polyester fabrics work great if you are certain it is 100% Poly and nothing tossed in the mix. I used it one time, and it ruined the panel I was making. It stuck to the point of not coming off without delaminating from the foam.

Sam's idea on the plastic is a GREAT piece of advice. If your goal is ready to coat finish, it works. It gives you a shiney surface. The Peel Ply method gives yo a flat finish, and is ready to coat with more epoxy without sanding.