Is vinyl spackling ok to fill gaps ? - RC Groups
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Apr 03, 2012, 10:43 PM
Registered User

Is vinyl spackling ok to fill gaps ?

got a couple of builds going on my work bench, one is a built up balsa Tug hull , i ll have a lot of fairing to do soon and wondering whats the best gap filler that is also easy to sand down, i have used thickened epoxy with talc before buts its not so easy to sand, wondering if vinyl spackling is ok to use, i most likely will cover with glass cloth after all is smooth, what fillers do you all mostly use ?
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Apr 04, 2012, 01:18 AM
Its only a model.
Tregurtha1013's Avatar
i've used spackle before. If you look on my Tug Victory build thread you'll see white stuff on the the pink foam hull early on in its construction, thats spackle used to fix my mistakes.
Apr 04, 2012, 07:14 AM
Registered User
Tregurtha, thanks for the reply, your tug looks awesome, what a cleaver way to build a foam hull , love all the free space inside the hull , ive got to try a build with your method, what thickness was the styrene sheets ?
Apr 04, 2012, 09:04 AM
Cheif Bottlewasher
more coffee's Avatar
The thickness doesn't matter i don't think,however getting the foam the same width as the stations are apart does..

If you don't mind as the lingo differs from place to place..What is vinyl spackle?
do you have a product name?
Apr 04, 2012, 12:37 PM
If it floats....sail it!
FoamCrusher's Avatar
Originally Posted by larryg
what fillers do you all mostly use ?
Bondo from the auto parts store. Some big box and hardware stores also carry it.

Smooths easily when mixed (it is a polyester resin and talc), cures hard enough to sand in 20 minutes - rock hard but still sandable in about 2 hours, sands easily, hardly shrinks at all as it cures and takes a sealer or primer well. It mixes at 5:1 ratio but the catalyst is deeply colored so you mix it to the color of the spatula (included in the blister packaged units or separately). Unlike an epoxy, it is very tolerant of being slightly off the desired mix ratio, but works better when mixed correctly.

The only downside is that a Goop size tube is ~$7. If you have a lot to do, you can buy it in a quart can at a far better price per ounce. On one of those 'late night builds' when I ran out of Bondo, I mixed regular polyester resin and baby powder as a substitute with good results.

The light weight wall patching compounds that were mentioned do work, but they don't bond very tightly and are prone to popping out of larger areas if the hull flexes. It is OK for small dents and dings. I use it to smooth the surfaces of EPP and EPS foam airplanes where weight is critical prior to painting or after being coated with 3/4 oz fiberglass cloth. Thinned to a slurry and painted on with the foam brush it makes a nice smooth surface. You do have to seal it before painting since it can soak up paint differently than the rest of the surface.

Apr 04, 2012, 02:52 PM
Its only a model.
Tregurtha1013's Avatar
Originally Posted by larryg
Tregurtha, thanks for the reply, your tug looks awesome, what a cleaver way to build a foam hull , love all the free space inside the hull , ive got to try a build with your method, what thickness was the styrene sheets ?
More coffee is right, the thickness of the styrene doesn't much matter. I think the stuff was like .70 mm on the Victory.
Apr 04, 2012, 08:07 PM
Registered User
At the recommendation of Laser110 on this website, I used vinyl spackle on my Jim Wilder hull. Works great, it's cheap, and it sands very easily.
Apr 04, 2012, 09:07 PM
Registered User
That Jim wilder hull looks great, the more i think about it the spackle should stay on fine because on top of it will be glass with epoxy resin so no problem of pooping off, i guess if the hull was just sealed with varnish it would be better to go the bondo route
Apr 05, 2012, 08:09 PM
Registered User
I confess to having used a little Bondo-like material to build up a sizable hollow near the stern, just 'cause I was unsure how thick I could put on the vinyl. But the whole hull was then covered in FG cloth and 2 coats of epoxy, so all is well.
Apr 05, 2012, 10:26 PM
Old wreck in Milwaukee
Prins Willem's Avatar
After some expensive lessons gleaned from 38 years in factories I try and stick with compatible materials. Spackle is formulated to bond to drywall or plaster, to wood less so. On a wood surface I use wood filler. For ABS I use Squadron putty (a tad pricey) or automotive spot putty (less pricey). If I have a deep void to fill I will glue in more of the base material, then fair with as little filler as possible. Gaps between planks just cut some long thin strips and glue in. Be careful with two part body filler. My brother used Evercoat brand on his fish tug. The first time out running strips of fiberglass peeled off because the FG didn't stick to the filler.

When in doubt always do a test piece. Sometimes things that should work don't, and some that shouldn't do. In another thread about gluing sintra a forum member said he couldn't get PVC cement to work on it, and sintra is PVC.

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