Hi all,

I need some help achieving my topcoat in less time. I have experimenting to do with smaller air caps but thought someone out there might have already achieved this.

I get a great looking and feeling satin/matte topcoat on mandolins and guitars by spraying 1.5lb - 2lb cut shellac out a Fuji HVLP M-Series gun with 1.3mm tip. The air is full on, vertical fan full on, and fluid control barely on. The gun is held about 4" away from the target surface.

The problem is takes a loooooong time to build. I can spend 20 minutes or longer of constant spraying to get the desired effect (Not a sustainable production or shoulder practice!). If the fluid control is opened a hair too much the result is a grainier surface texture comprised visually of larger droplets.

Schedule:

1. Build coats leveled with 400 grit.

2. Final coat is knocked down with green 3M scour pad leaving very fine scratch pattern.

3. Top coat as described above.

I hope the smaller air caps will atomize more finely even at higher fluid levels, thus resulting in similar effects in less time. Maybe I can output more fluid and hold the gun farther away without it hitting the target dry.

I know I could use a topcoat with flatteners but the results I get are fantastic, plenty durable, easily repairable, and there is virtually no chance of getting a goober in the topcoat as it is so thin and dries so fast nothing get's buried in it.

Thanks for any insight!

Derek

I don't think I would spray it. I would brush it on. Let it dry, sand it back with 3m gold 220. Maybe do that a few times till I got the build then pad it. 20 min of continuous spraying just sounds like a problem. If it is going on wet while spraying, the outer part of the shellac will be dry but the underneath will be gummy.

Thanks Pete. The spraying I do now, although I agree is too laborious, is still less time than brushing, sanding, then padding. It seems I have a topcoat technique that I always hear should be problematic but I ensure you it is not. It is ultra thin, holds up to scratch testing, looks and feels great, and never had a complaint. It's a really small amount of liquid coming out of the gun. I posted a few photos to give an idea of the results.

View higher quality, full size image (480 X 640)

View higher quality, full size image (480 X 640)

View higher quality, full size image (480 X 640)

Wow, I only use green Scotchbrite to scrub pots and pans! I'd suggest you not sand between every coat if you want it to build faster. I'd also narrow the pattern and open up the fluid. But I've never sprayed from 4" away, and never used a Fuji HVLP M-Series.

Thin down the shellac and rub out with 4/0 steelwool and wax?

I have only sprayed shellac with a hvlp conversion gun. I use a 1.0 set with great results. You may want to try a smaller needle/nozzle, or check the viscosity of your cut.

The viscosity of the material is too thick for your current size nozzle... think of trying to push a milk shake thru a pin hole versus thru a straw.

If you like how your current material flows out and hangs on vertical surfaces then get a bigger needle/nozzle set. I would think a 1.6 might work.

If the 1.3 is all you have then you will need to reduce the material.

ronb