cotton flock as thickening agent

83mulligan

Senior Chief Petty Officer
Joined
Feb 7, 2009
Messages
687
My local fiberglass guy was showing me cotton flock as an alternative to cabosil as a thickening agent. Much less nasty dust to deal with. Anyone have experience using it in boats?
 

saildan

Petty Officer 1st Class
Joined
Mar 7, 2009
Messages
264
Re: cotton flock as thickening agent

My local fiberglass guy was showing me cotton flock as an alternative to cabosil as a thickening agent. Much less nasty dust to deal with. Anyone have experience using it in boats?
It seems to me the job would dictate the type of filler you select.

Fumed silica (Cabosil) is a non-crystalline silica, the material that comprises sand, only the processing leaves it bumpy and lumpy rather than crystal like smooth sided for greater surface area and hold with the resin.

Mix resin with cabosil and it not only thickens, but it hardens. So if your gap fill or gusset needs a hard/strong resin mix I'd think this or something similar would be the choice.

The other strengthening filler is chopped or milled fibers, usually glass.

Between the two you could compare them to adding aggregate stone or rebar to concrete as strengthening agents.

The other type fillers bulk up the resin so it's not runny, but their other effect is to modify hardness. These include talc, plastic or glass micro-bubbles, wood flour, wheat flour, and I guess cotton flocking.

Resin fluffed up by these fillers would fill gaps and be easier to sand, but though strong by their own accord would not be the same sort of hard strong the first batch of fillers would be.

If you are fairing or wood crack filling, cotton flocking might work ok, but if you are setting a new transom it could be a little wimpy.



Get rid of the Planet of the Apes dust mask

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and get something that really works

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your health is worth it.


:)
 

Peteco

Seaman Apprentice
Joined
Aug 12, 2009
Messages
36
Re: cotton flock as thickening agent

Flox (flocked cotton) is a structural filler, much like milled fibers or cabosil and makes a very strong bond. It will not be easily sandable.

Cabosil is much the same, but when your mixture is thick, cabosil usually helps to spread better as opposed to rolling up. It's thixotropic, like grease (but you usually wouldn't be spreading a mixture of epoxy and flocked cotton across a surface like that anyway). You'll notice that grease shears easily, but sticks in one place when undisturbed - cab is the same.

Microballoons (glass, phenolic, or quartz) are not structural, but are instead used for (1) an easily sandable filler, usually for surface finishing skim coats that will be sanded down, (2) to build bulk or thickness in a mixture when strength is not critical, or (3) to create a syntactic foam patch/filler when building with foam cored structures.

Flox will be a fine structural filler for your boat.
 
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