body work is about done on my plug… time to lay down some duratec.
i have used duratec before, but brushed it on… nightmare to sand the whole surface smooth.
this time i am equipped with a 60 gallon compressor, dump gun (#4 and #6 tips), and HVLP gun (1.4 and 1.7 tips I believe).
which gun should i use? my biggest fear is using the HVLP and having the duratec gel up inside (ruining it).
thoughts? in the end i need to sand it down to a SMOOTH finish to waxing and mold time.
-Andrew
Hi Roo. We use a hvlp gun ( 1.7 is the better choice of your tips) to spray gel coat and primer. Just mix 10 ounces at a time… get a helper to mix while you spray.
Thin it with 10% acetone. catalize it on the slow side.
Clean gun with acetone or laquer thinner when done, also break the gun down and clean the air cap, tip, needle and gun nozzle with a brush when done. The first coat going on you want to just mist on. Let that sit for 5 minutes then do wet coats until your satisfied. Between each coat i would wait a few minutes to let it flash. This so you don’t get runs and a lot of trapped solvents in the primer.
I personally have never used a dump gun but to me it just seems you would obtain a better finish with a gun that fully atomizes the primer/duratec.
duratec recommends 2% i believe for catalyzing… so maybe do it at 1%? (half)
i thought mixing duratec with straight acetone was a no-no?
thanks for your response!
i thin all resin type liquids with acetone for spraying. It always works for me. If you are not sure how it will work with your Duratec just spray a test panel. Or if you can get it to spray nicely without thinning it then no acetone would be needed.
1 to 1.5% yeah. My resin supplier recomends 1% but i am in hot Phoeni AZ. You may have to wait 24 hours to sand and buff your plug if you plan on those steps.
I’ve had good luck with a big tip (2.5mm) gravity feed gun. Duratec also makes a thinner specifically for this product that works great. I’ve thinned this up to 15%, which yielded nice flat finish. This combination also puts a good deal of material on the part.
You should check out this tech note: http://www.duratec1.com/pdf/MoldResurfacing.pdf
i for sure plan on doing a test panel with both guns - just thought i’d throw this out there.
i did do a search on here - one member stated they used a dump gun with #4 tip, thinned it with a type of reducer, and sprayed at around 25psi.
if using less material to catalyze, i don’t minding waiting a day or two to sand / polish. better then ruining my hvlp gun by having it gel up / dry inside… that’s why the dump gun idea sounded so appealing.
-Andrew
I add 1% catalyst to the polyester duratec gel coat. Am I under catalyizing?
I never thin it, and I spray it out of a 1.2mm mini HVLP gun. Works great!
Fixed the thread title. I hope you don’t mind Roo
I just had to spray duratec, and tried it out of my dump gun with a #4 tip, and out of the 16 dollar harbor freight HVLP gun.
I thinned it with 10% lacquer thinner when spraying out of the dump gun, and 20% when spraying out of the hvlp gun. I agree that catalyzing with 2 pct is far too much, I aimed for between 1 and 1.5 pct.
Overall, I was wayyyyy happier with the results out of the hvlp gun from harbor freight. Sprayed it at 30psi with a fan pattern similar to what you’d use on an automotive job. I’d say it took about 3 passes to build up a layer that I was comfortable with (didn’t actually check it with a gauge; duratec can cure at 10 mils and I felt that my 3 passes gave me at least that amount).
For clean up I just poured in quite a bit of acetone and flushed it through the gun as if I was cleaning out a 2K poly paint.
I asked the rep at the S.A.M.P.E. convention @ LB. What was the best for thinning duratec?
Answer “MEK” (methyl ethyl ketone without P)
he said acetone will work but makes it flash to fast.
I have been using for many years. It’s hard to get in CA. now.
home depot carries MEK substitute. I even checked AZ. I tried it on a small repair recently and it worked fine. Since then I found an underground source.
If you are talking about the primers, I use lacquer thinner and kick it at 1.5% most of the time. The trick is don’t stop spraying. If you are dawdling around trying to be Mr. Perfect, you might end up with a cup full of plastic. Doesn’t mean you can’t do a decent job, just don’t spend forever trying to get it perfect.
This thread is back from the dead! Now I use a 1.8 tip for clear Duratech @ 2% catalyst and 0% reduced. For the primer I’ll do one of two. 2.0 Tip reduced at 10 - 15% with MEK. Or I’ll use one of those pressurized HVLP where you have the little rubber hose going from the spray gun air chamber to the top of the cup. No reducer if I do this.
I’ll use the first method for priming finished pieces for mold making. I’ll use the second method for priming foam out of the CNC machine.
Even if I had to reduce at 20% I wouldn’t care to think about what I’m doing to the properties. If I’m making plugs, they go in the garbage in a few days anyways. I never have to worry about the primer withstanding the test of time.