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Part# 09-28280
MFR Model# 16-SPU


The pinhole killer! Waterborne polyurethane primer plus UV blocker applied with a foam roller or spray gun. Fills pinholes in layups or molded parts. White color. Once UV Smooth Prime has dried for 7 days, spray white two-part catalyzed Epoxy Primer to seal the surface and provide moisture and chemical resistance prior to spraying top coat paint. Dry sand for a smooth, pinhole-free surface. Dries in 20 minutes, sand in two hours. Clean up with water. Use Poly-Fiber Gun Cleaner to clean your spray gun after each day's spraying. NON-HAZMAT. Three gallons required for most composite aircraft.


Important Notice: All mixed paints are special order and are non-returnable.
California Prop 65 Warning Symbol

WARNING: The product may contain and/or expose you to a chemical(s) or substance(s) which are known to the State of California to cause cancer and/or birth defects or other reproductive harm.


Great Stuff, fills imperfections, pinholes and weave voids in my Lancair project. It’s just the right consistency for a foam roller application sands easily leaving a ready to prime - baby bum - smooth surface. Love the fact I have the option of not spraying it on.

Gary M
April 5, 2021

Stir well, goes on like a thick milk. Be sure to apply in thin coats, and do at least 3 prior to sanding. I sanded with 1500 grit.

Chris D
August 4, 2019

At first I did not like this product because it seemed really thin when applied. I then double checked my mixing and I needed to stir more to get the product that had settled in the bottom of the can. Then it was a little thicker than milk.

Chris D
July 15, 2019

Great for filling those last pinholes

Wayne P
January 13, 2019

Expensive but the best product available.

Lional R
July 2, 2018

Great product, has affinity for epoxy glass and well as metal. Rolls on easily with foam roller. Fills pores readily in epoxy parts, sands almost as easily as drywall mud. Easy to feather edge. A new can is difficult to mix up initially.

Rich F
October 9, 2020

Requires a lot of effort to properly mix solids into carrier even with a powered stirrer. Product works very well when thinly rolled on with foam roller with many overlapping strokes which aids in forcing the filler into the pin holes putting on too much will cause runs and sags. Sands very easily and smoothly when dry.

September 5, 2018

Be advised, the can has new instructions and directs you to clean the fiberglass with acetone first, then use diluted 310 cleaner, rinse with water, then use something called prep wipes before spraying. So far I cant find a source for prep wipes and hope to find a suitable cleaner locally.

July 21, 2018


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Is Smooth Prime thinned or diluted with anything?

Per the manufacturer: No, it is not thinned or diluted.

Q: Does UV Smooth Prime have a shelf life? How do you dispose of this item?

This material has a 4 year shelf life in a sealed container. If the material is dried out to a solid piece is can be thrown in the trash, or it can be taken to your local haz mat disposal facility.

Q: The manufacture date on the contaner is 1903013, can you tell me when this was?

The first two are the year, the second 2 are the month and the rest is an internal vendor code. This would have a DOM of 03/19 (March 2019).

Q: Please tell users they MUST use a drill motor and stirring wire to remix before use. There will be a Big Lump of Clay in the can to be re-mixed into solution. You have to probe around to find it.

Thank you for your feedback. We will post to our Q+A for other customers to see.

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