Any tips on doing faster layups with mat?

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#1

I’m not looking for a “magic pill” or anything, I know it’s going to be time consuming, I’m just wondering if there’s any techniques that might speed it up some. My part is roughly 3’x4’ and isn’t too complicated by any means, just a little curvy. It took me about an hour and half to do a layer of 1.5oz mat last night. It doesn’t really seem that long when you’re doing it, then you look at the clock when you’re done and :eek:. In fact, looking back, I don’t see how it could’ve, but it did. However, I got a little faster once I started using a brush in one hand and a roller in the other.

So how do you layup mat? Say you’ve done your gelcoat, filled the corners and laid your first layer the day before. The resin I’m using has wax so I sand the previous layer and put some catalyzed resin on the piece and start laying mat. Do you cover the entire piece with a complete layer first? Or do you work in sections doing three layers at a time until you’ve made your way across the entire thing? If so, do you put on a piece, completely wet it out, then put another piece on top of it and so on, or do you put a couple of pieces on top of each other and wet it out, etc.?

With how long it takes to me to do a peice that size, I couldn’t imagine being able to do a hood or bumper or something without having multiple people. I guess a hood might not be that bad since it’s so flat, but say a bumper, how long would it take someone to lay something like that? I could see throwing in some resin and doing a quick inital pass on all the mat, just getting it wet enough in spots for all the pieces to be stuck down and not go anywhere, but with the time it takes to come back and get it 100% saturated and all the bubbles out etc, the other end would start setting up before I could get back across the entire piece.

Any advice or tips? Even if it just saves a few minutes, every little bit counts right?

#2

What is tthe rating oz.'s of the FG mat that you are using? If 3 oz, then split it in half.

If you are using PER lam resin without wax, you won’t need to sand it at all.

Pre rip your mat to fit and then some extra too.

Mix up a big batch of resin and pour in on and spread it around. Throw down the FG mat and use both hands like you stated.

Get a friend or someone else to help you…

#3

I’m using 3/4 oz for the initial layer and 1.5 oz for the rest.

I’m glad you said that. I plan on buying some without wax next time, but how long do you have before you would need to sand to add additional layers? Is there a time limit? Hours? Days? Not that I ever plan on waiting that long, but just wondering.

If someone were doing a bumper or something, is it generally done with more than one person? Or just add less MEKP to give more working time?

Thanks in advance!

#4

Only use the PER with wax as the last resin layer as if you don’t sand / wash the wax off (acetone), it may delaminate later with the wax stil on the inner layers.

The wax comes to the surface during the B stage so…

Composites takes time and that is the most of the costs.

Yes, use less % of MEKP for a longer work time and not as brittle part after it is done.

Also, you can pour the mixed PER onto the mat and just let it soak in to break down the styrene binding agent and it works easier too.

#5

LOL, I was gonna post this same question! Wet laying up mat is back breaking work. And I hate standing there dabbing with the brush, seems to take forever.

I mix my resin in a disposable paint tray and lay the mat in it part way to soak in some resin. Then I slide it over to the flat part of the tray, fold, and roller/squeege it to even out the resin.

If the resin is thin enough, I can do 3 layers at once. It’s limited to smaller pieces though.

I need a chopper gun…

#6

Never used anything but hand lay up to make motorcycle fuel tanks, and this always results in quality parts, with none of the problems associated with chop guns or RTM processes.

Guess though hand laminating is not something that its possible to do well without some amount of practice/experience, and it did take me quite a while to get good results.

#7

Mat soaks up lots of resin. What I do is wet the part first with resin. Then I lay down the mat. Then I apply more resin over the top to wet out. Then I hit it with the bristle roller. The most time consuming part is stippling in order to remove air. The roller saves a lot of time.

#8

If you are likely to be doing a great deal of hand laminating, of smaller parts, then the process can be speeded up considerably by pre-wetting out the mat with resin. Have seen machines specifically for this purpose, but it would probably be possible to make one quite cheaply.

#9

What I’ve been doing lately with some success is using my cup dump gun with a tip that I drilled out. I mix up about 400-800gram of resin at a time and turn the pressure way down on the airline ~20 psi. Then I just spray the mat with the cup gun, it saturates a large area fairly quickly. Then I put it in the mold and start rolling. If there are any dry spots, I spray over them again.

The only issues are that you have to keep moving or you’ll have to stop and clean the gun, and you have to experiment with the air pressure. You don’t want to atomize the resin, you just want to push it into a slight fan pattern as it runs out. It just sort of splatters out of the tip and into the mat. Also, it takes a little experimenting to know how much resin is enough as you spray it out.

Works well so far…

#10

I’ve tried something similar using a texture gun from Harbor Freight, can’t remember why, but I didn’t like it.

I was thinking of building that roller thing that Classicbike mentioned too. I wonder how often you have to clean the rollers? I’ll stick to my method of pre-wetting in paint trays.

What gets me most is the strands every-damn-where!

#11

Ill have to give the tray thing a try…and squeeze the excess off…

How do you keep from wasting a ton of resin? I got a new resin to sample infusing, color stays neutral but man is the work time fast.

#12

That’s the hard part, I usually just under-mix…also, I always have one hand holding the mat while I’m dipping and then rolling it out, so that leaves a small dry corner which I do the brush-dabbing way. Again I really only do this for complex curves, otherwise I’ll just dump resin on, lay mat, and roller it in.

There’s still gotta be a better way…

#13

I would have thought laying parts up by pouring resin over the mould surface is going to result in either heavy brittle parts with excess resin content, or alternatively a real need to spend a lot more time removing the excess resin from the lay up.

Look carefully at the resin system being used, and make sure its suitable for hand lay up, and isnt something intended for RTM process, which will be very difficult to use for hand lay up, as its not going to have enough viscosity.

#14

Yeah it ends up being pretty resin-rich, even though I try to mix to get a good resin-mat ratio.

#15

If you take a little more time with hand lay up, then its possible to make good quality parts, without excess resin content.

As you get more experience you will be able to work faster, and probably wont find there is any need to pour resin into your lay ups.

#16

yeah its called a chopper gun.