Gel coat diy ?

[badluck]

Can anyone refresh my memory on gel coat. I built a swim step 6-7 yrs ago with fiberglass and gel coat. It was supposed to be a trial/mock-up but I’ve been using the crap out of it. So much that the gel where I slide off the back with my ski is gone. I’m spraying it with the glass bottle and canister from Home Depot. I remember having to thin it to spray. But I don’t remember the ratio. I believe I thinned it w/acetone. Is there any additives needed or do I spray the gel 3 coats or so with a wax spray on the last coat? Sand between coats?
thanks in advance

 

[wzuber]

If the glass/gel coat is polyester up to 10% acetone, OR... up to 50/50 27x1 to thin for spray. (Prestec 27x1 gives more gloss and completes cure w/out pva cap ) Apply wet coat build up to maybe 10 mils let tack off, then apply another 10 mils etc. Let final coat tack then spray with PVA to cure. (If acetone thinned) sanding between coats is only necessary if you use wax or the gel cures fully.

 

[Gelcoater]

Can anyone refresh my memory on gel coat. I built a swim step 6-7 yrs ago with fiberglass and gel coat. It was supposed to be a trial/mock-up but I’ve been using the crap out of it. So much that the gel where I slide off the back with my ski is gone. I’m spraying it with the glass bottle and canister from Home Depot. I remember having to thin it to spray. But I don’t remember the ratio. I believe I thinned it w/acetone. Is there any additives needed or do I spray the gel 3 coats or so with a wax spray on the last coat? Sand between coats?
thanks in advance

I think I’d hit harbor freight and get a cheap little spray gun so you can thin the material less and get better mil thickness.

 

[badluck]

I have an older sharpe hvlp gravity gun. Will that work?

 

[wzuber]

that will work as long as you don't move faster that the material will flow. What size tip?

 

[Gelcoater]

that will work as long as you don't move faster that the material will flow. What size tip?

There’s the key!
Tip size.
Typical automotive tip sizes are smallish, and made for flowing liquid. Gel is closer to latex in thickness, thicker usually.

Not sure what repair guys run for tip size but for in the mild work I use a 68 tip on my Binks gun/pressure pot.

 

[coolchange]

I’ve used a 2.5 to spray gel, works ok for small area.
Just sprayed some 50/50 black with dura tec clear out of a 1.4 . Sprayed similar to imron.

 

[badluck]

I’ll have to look but I think it’s a1.8. I think k200 was the last time I used it

 

[onefastt]

Buy a gun with a 2.5 mil tip off of Amazon. Thin with up to ten percent styrene. Or mix 50/50 duratec to gel and it will shoot out of any hvlp gun.

 

[badluck]

Do I need to add catalyst to it or just use Pva on top of the last coat?

 

[wzuber]

Do I need to add catalyst to it or just use Pva on top of the last coat?

Catalyst to the gel coat...yes. For polyester I believe the general rule of thumb is 2X's the amount for straight resin. At least that's what lilly-ram gel coats require. If spraying something else best to call them for their ratio's specifically. Remember ambient air temps effect cat. Ratios and cure times. Also add cat. To mixture just before pouring in the gun and spraying immediately afterward. The bulk material will kick off fast in the cup so have everything completely ready to spray before mixing.
No catalyst w/pva. Shoot that stuff straight outa the bottle. Clean gun up with soap n hot water very shortly after ward. I hope this helps.

 

[wzuber]

Note...if thinning with styrene as has been recommended it may change cat ratio's from what I stated so best to confirm with product mfg. Tech dept. 1st. To get the most accurate info..I'm not familiar with styrene but I would certainly like to know more about it if anyone wants to share? Anyone? Anyone?....bueller? Haha

 

[Gelcoater]

Catalyst to the gel coat...yes. For polyester I believe the general rule of thumb is 2X's the amount for straight resin. At least that's what lilly-ram gel coats require. If spraying something else best to call them for their ratio's specifically. Remember ambient air temps effect cat. Ratios and cure times. Also add cat. To mixture just before pouring in the gun and spraying immediately afterward. The bulk material will kick off fast in the cup so have everything completely ready to spray before mixing.
No catalyst w/pva. Shoot that stuff straight outa the bottle. Clean gun up with soap n hot water very shortly after ward. I hope this helps.

To be clear with what he said.
Yes you have to use catalyst in the gel.
The ratio is 2%, not 2x, lol.
The pva you shoot straight out of the bottle.

 

[Gelcoater]

And yes added styrene will boost the gel time.
I’d use it sparingly, more styrene=more brittle anywhere it’s thick.

 

[wzuber]

To be clear with what he said.
Yes you have to use catalyst in the gel.
The ratio is 2%, not 2x, lol.
The pva you shoot straight out of the bottle.

Thanks for the clarification on that G.C. I was told @ the suppliers to double the amount of catalyst for gel coats (only). So that's not necessary (required for proper cure) then? Can the pva be sprayed directly following gel spray or should it be allowed to flash off some first? Thanks for the clarifications. I always appreciate the correction info.

 

[badluck]

I plan on doing a few coats.
Step
1 sand it 120 grit
2 wipe with acetone
3 shoot with gel coat no catalyst
4 after last cost spray with pva

questions
1 how long between coats?
2 can I mix gel coat with acetone or styrene?
3 cure time after pva?

 

[wzuber]

I plan on doing a few coats.
Step
1 sand it 120 grit
2 wipe with acetone
3 shoot with gel coat no catalyst
4 after last cost spray with pva

questions
1 how long between coats?
2 can I mix gel coat with acetone or styrene?
3 cure time after pva?

step 3 is incorrect. it will never cure w/o the catalyst.
step 1A.....I would add blow off with clean, dry air

Q1- if your not excessively thinned you can easily spray 10mills in first coat, let flash for 30 min. then spray another 5-10 mills for final app. Note clean gun with acetone thoroughly ( brush behind fluid cap etc. ) between applications.
Q2- yes...see gel coaters above comments on styrene.
Q3- Depends upon specific ambient air temps when applied and volume of gel coat and catalyst ratio. But generally a couple hours at least.

 

[badluck]

How long between coats? I’m in it now!

 

[wzuber]

How long between coats? I’m in it now!

20_30 min.?

 

[badluck]

It’s laying flat but is drying with no shine.